How to Stop Damp Mould & Condensation - a COMPLETE Guide

[@SloopyDog]

I was born in 1947 we lived in a council house with a coal fire. We never had any damp or mould problems. We had an oven in the kitchen linked to the coal fire. My mother often dried clothes on a clothes horse put in front of the oven, and still no damp problems. We didn't have radiators all we had was a back boiler behind the fire to heat the water. Coal fires allowed the house to breathe. Later on, the council fitted a gas boiler and radiators. That's when the problems started, we started getting damp problems, the windows were always damp on the inside. Many years later I had a Housing Association bungalow, due to my health problems. The Housing Association in their great wisdom decided to insulate the loft to the current standard. A damp-proofing firm filled the cavity walls with insulation( pumped in). That was when the bungalow started getting damp problems. Mould started to appear on every wall. It became a constant battle to keep the walls mould-free. The windows were always streaming with water. My wife and I are in our late seventies and in very poor health, I try to keep windows open as much as possible, all the time in summer. We are causing more problems by having our homes over-insulated. The house needs to breathe. Cavity walls were designed to do just that. There is no great mystery as to why people have damp problems. Many people can not afford to heat their homes as due to an incompetent government fuel prices have gone through the roof. People on minimum wages and pensioners on a single basic pension, like myself are struggling to live. In this country, the rich get rich and the poor are forgotten about. The basic pension starts at £130, you don't get far on that. I would like to see if the Prime Minister or our overpaid MPs could survive on what I have to live on. THERE IS NO WAY THEY COULD.

[@CharlieDIYte]

Sorry to hear about the problems you face now and thank you for explaining how the situation has changed over the years. It was makes perfect sense given the need to ventilate houses.

[@steffananthonyholden2752]

The problem is there was no clear strategy initially with insulation measures - now under Pas2035 the government intends to rectify all of this - “there is no insulation without ventilation” which is the causation for most your damp and mould symptoms … measures installed in isolation never work effectively - there has to be a conjoined approach and strategy …. Much in the same as if you improve a cars BHP you must improve its breaking capacity …. The old open fire houses had a mass of ventilation via the stack so RH never had time to condense and air changes were at a rate of 2/5 …. Of course the only way to heat the property was with fossil fuel and this is now to be banned …. And just to add , the mechanical operation of ‘opening windows manual will never work , nor will trickle vents long term

[@kevinwalsh8483]

Got a stove fitted before Christmas used to have an open fire.. windows are destroyed now due to the chimney been blocked now. Always had clothes on the rads drying.. so annoying

[@zane___k7333]

Because the fire gives off a lot of infared heat. Which reduces relative humidity.

[@user-bz9cb8bp2y]

We have candles, gov calls it affordable heating in UK 😂❤️❤️🇮🇱

[@bobbobson4069]

This is by far the most comprehensive "documentary" on the phenomenon of damp/mould and how to reduce it. I really appreciate the astonishing amount of work that has clearly gone into the making of it. The science and home experiments are fascinating. I can honestly say that I really understand the whole phenomenon much better now. Well done! I have of course liked and subscribed as a result! (Marius Gudonis, originally from northwest London, but now working in Warsaw)

[@YellowPinkie]

As a building services engineer, I can state that is the simplest and easiest to understand explanation of RH. Good work Charlie!

[@CharlieDIYte]

Thanks, Stephen I massively appreciate that!

[@andrewstones2921]

I agree with Stephen 100%

[@npr1300A8]

Brilliantly explained. Thank you.

[@joeslacker1020]

​@@CharlieDIYte Hey you say to have a ventalation system or an Air Conditioner to circulate the air, but what if it's in a rainy area and you have a heater on with the AC or it on fan mode in a travel trailer? I thought the cold air from the outside meeting with the warm air inside is what causes the moisture, so why would putting air from outside inside cause it to be less moisture?

[@kenleehk65]

Perhaps to add a bit more accuracy to that statement..."Relative humidity is the amount of moisture in the air relative to the amount of moisture air can hold, influenced by its temperature "....yes, the air pressure also plays a part in how much moisture air can hold at atmospheric conditions. However, changes due to elevation and weather may contribute to a certain extent, though not massively.

[@mikebarber458]

Hello !! I've been a Master HVAC contractor for 30+ years and I really liked you explanation of dew point and RH . I have many clients in a high rise condo building in a very mixed climate of Richmond va. Floor to ceiling glass walls on one or more sides. The windows are double pane but the framing is aluminum. I've been dealing with the frames condensating for years. Dehumidifiers as you said solve most of the problem, but coupled with air flow from floor fans and or ceiling fans solved the rest of the issues. Combined they totally eliminated condensating. I've automated some Dehumidifiers to work in conjunction with the air handlers fan. I got excellent results

[@corvoattano9303]

Hello. From reading your comment am I correct in assuming that high airflow around areas where condensate builds up helps to mix it back into the room air which can then be removed using a dehumidifier?

[@mayhemuk88]

Removing the wife n kids helped alot especially when they have a bath/shower, ooh too cold to open the window, great video and well explained

[@markbriggs729]

Another +1 for PIV. I Moved into an early 1900's bungalow in Essex a few years ago and humidity levels were getting up into the 80's through the first winter. At one point water was streaming from the single glazed windows, down onto the windowsill and puddling on the floor. You could sense it in the air as well, everything would feel damp and there was a constant musk. I installed an extractor in both the kitchen and bathroom and changed all the single glazed windows to double and although this did help with the build up on the windows it didn't have much effect on the levels. I then tried running a dehumidifier and although this was somewhat successful it was only whilst it was running. As soon as it stopped the levels rose again. Last year i went with a loft fitted PIV with no heat and almost instantly the levels dropped down into the 40's. Even through the worst of winter it only crept up to 60% a few times. I have it fitted in the hallway and you can notice the temp if you stand right under it but it's a small price to pay for having no condensation or mould in the house. It even seems to force the air into all of the rooms quite well under door gaps etc. I now have that running all year round, use extractors in the kitchen and bathroom and put the dehumidifier on next to the clothes horse when drying clothes inside in the winter with amazing results. Quite possibly the best purchase i have ever made. If anyone reading has similar issues in a similar property i can't recommend them enough.

[@MTechOver9000]

Hi Mark, I came across you comment here, thanks for this info. This was made 6 months ago, would you still recommend the system you have? Which brand did you go for? Many thanks in advance

[@That1ufo]

After a flood they say it takes months to dry out with dehumidifiers, was the house empty not heated when you moved in? The clothes horse was probably the biggest problem or rain coming in the walls, get a condensing dryer!

[@pavel9652]

The line of logic regarding dehumidifier is flawed. You wrote it was somewhat successful when running. So is the piv, because it somewhat works when it is running. I think there is another problem, just like people suggested, it was damp because being vacant for a long time or there is a leak. Check the plumbing. I lived in the house where there were THREE small leaks simultaneously, under the main hot tank, shower and the small hot tank in the kitchen. That had risen moisture levels significantly in all the locations without producing obvious signs of leak.

[@JayL123]

@markbriggs729 Would you need Trickle vents on the windows for PIVs to work? None of the rooms have ventilation holes in the wall but have trickle vents in the windows. We plan to change the windows and I wonder if I have to get tricke vents in it for the air to flow. Apologies if its a silly question, but the trickle vents are all dusty and mouldy.

[@lynnfincham6839]

I have PV has helped but had to do many other things to control mould ect. Think every house has its own individual probs. I run dehumidifier too. With extractor fans bathroom kitchen. I don’t ever dry washing indoors tho ever. So much water your introducing back into the property. Dry on line as much as possible. Even put washing in summer house not main house. 😊

[@alanedwards9069]

Moved into a circa 1900 mid terrace stone house 3.5 years ago, had major issues with condensation for around 18 months until I installed a PIV. Stopped it dead. Within 2 days I put away the window vac and it’s been there for the last 2 years. Installed over the staircase and the only time you feel cold air is when walking up the final flight of stairs (three storey house). House went from 80%+ humidity to between 40-50% virtually overnight

[@philipoakley5498]

what size was it & was it costly? (even if in retrospect it was the best pounds spent ;-)

[@noneB974]

total price with breakdown please?

[@lh3690]

Seriously one of the best videos on this topic I've seen. I'm new to being more humidity aware due to issues at our trailer. This explained things so clearly and to the point that I feel like I have a much better base from which to address our issues and less anxiety about unknowns.

[@CharlieDIYte]

So glad to hear that. I recommend getting a hygrometer, that way you know where you stand and what steps you need to take. 👍

[@davidiand7]

Excellent video Charlie well done! I’m a Brit living in Sweden, all houses here built in the last 50 years or more have some form of ventilation system, be it natural draught ventilation pipes from kitchens and bathrooms, fans in the roof drawing air out of the house 24/7 (my current house has this, it works well, some windows still have the original paint and the house was built in 77). I have lived in a house with a heat exchanger, this would be my system of choice, I have known it to be down to -15 outside in the house +22 and the radiator was hardly on, you could hold your hand on it without it burning. (Heat systems are a little different here but that’s another subject). People do not use heavy curtains here, they are normally not drawn, they are light weight net curtains and for decoration purposes. Usually Venetian blinds are installed between the glass pains in the case of triple glazing older style, or you can have triple glazed window with an envelope with a vacuum and an envelope with argon gas which are great, sometimes they have condensation on the outside and when it really snows, it can lay against the glass for days without melting, I currently have both types installed all windows have ventilators built into the frame which you can control, I never have condensation. Having said this in this part of Sweden the RH is lower than the U.K. which is surrounded by seas. When it is a minus temperature outside the RH can drop dramatically I have seen the RH as low as 20% which is not so comfortable, at the moment I have 45% and it’s -3c outside. I have an alarm system which has smoke detectors with temperature and humidity sensors, even when I am not home I can see the humidity and temperatures in the house on my phone. As you say condensation can destroy your home but more importantly your health! Incidentally the main heating system I have is a warm air pump, they are a like an air on unit but push out warm air, it circulates the air round the house and can be used in the summer for cooling but it’s expensive to do that, I do have it on when it is hot sometimes. Sorry this sitt is in Swedish but you can translate using Google www.bast-i-test.se/tester_pa_basta/luftvarmepumpar.html

[@jesshothersall]

My life changed overnight when I bought that Karcher a few years ago. My Crittals turned from opaque waterfalls to windows in one hit, and the bonus is, I'm cleaning them daily with distilled water, as the karcher moves over the glass. Not only left dry, but also clean, what a result! We already opened our decent size bathroom window, daily and I have a condenser drier, but you have to leave woollens on a rack, and denims too. Interesting and informative video as always Charlie, thanks very much :)

[@CharlieDIYte]

Great work Jessica. You've pretty much got all bases covered there. Could be with buying a hygrometer just to keep an eye on moisture with that stuff hanging up to dry but doesn't sound like you've got anything to worry about 👍🏻

[@markkendall6854]

Another vote here for PIV, a landlord of an end terraced old house with no cavity I the walls, spent a couple of grand fitting insulated plasterboard on the inside of external walls. Even lent the tenants a quality dehumidifier, but only fitting the Nuaire PIV solved the problem. It cost me a good tenant too, trying actively to resolve the problem. Property is now condensation free. This will be my go to solution 1st step in future.

[@BarnzyHQ]

Did your insulated plasterboard become wet ? Or was that dry before you fitted the PIV

[@JamesScholes]

Thank you for this video. I finally decided to take action on your advice and to stop breathing altogether. Breathing has been the root-cause of many of the problems in my life anyway. For example, I stubbed my toe the other week and afterwards it dawned on me if I wasn’t breathing this would have never happened to me. I’m also getting tired of inflating my lungs only to deflate ‘em a few seconds later (I mean seriously, who’ve got time for that?). Anyway, your video was the final nudge I needed to take action and I’ll be sure to credit you and your video regardless the outcome. Thanks again.

[@CharlieDIYte]

James, James you need to START BREATHING AGAIN 😬 Very drole but I hope you found the video useful.

[@annaartesana2622]

Funny

[@alexonfilm]

I'm right there with you. F'ing hilarious.

[@thequaintandquirky]

Love this 🤣

[@janettemajo2205]

Hilarious don't stop breathing please😁😂

[@DennisMcDermott]

I fitted a PIV unit a couple of years ago in my bungalow, this was in January, the next morning I had no condensation, and have not had any since. It does not make the area where it is installed cold, brilliant system.

[@simonmccutcheon7085]

Hi, which system did you have? I am looking at one by envirovent

[@geoffwoollen]

@@simonmccutcheon7085 Dont buy a PIV as Dennis- it just wastes heat and creates cold spots. Get a MVHR as per video. eg, Nuaire An easy DIY install in the loft and extract the damp air from the bathrooms, whilst inputting fresh air heated by the extracted air. Picked up mine from Ebay.for £200

[@matthewharding89]

We have a 170 year old terrace cottage. Modern render, windows and plaster. We tried everything. Even without changing our habits with the shower, cooking, boiling the kettle and drying clothes, we installed a PIV unit and the results have been dramatic. We've gone from up to 80%RH to

[@speedfinder1]

I've had a PIV system like the one you show, since 2010. It inputs into the central hall directly above the water radiator. It has vastly improved the moisture problems in my 1930s solid brick house. I still have other systems in place, but it is a good percentage of the solution to my damp issues in the winter.

[@thepaintedsock]

Hi. I had one installed recently. It made no improvement to humidity after a week. Have you actually measured yours? Before and after?

[@speedfinder1]

@@thepaintedsock Sorry, I didn't do any Before and After recorded tests. I just know that the damp smell in my house went away after a while with the PIV system running continuously over about a 6 month period. There is a chance that you may have to be patient to see any measurable improvement as the humidity content in the atmosphere in your home may be being kept high by residual humidity in your soft furnishings, or in fact the buildings structure. "Air Conditioning" of any type does take a while to show any real results unless it is working inside a sealed water tight box. This isn't a cop out answer but in my modest experience, these things tend to need either to work in conjunction with a refrigerant or dessicant electric dehumidifier for faster results. Good luck! 👍👍.

[@mosmes02]

@@thepaintedsock if you don't have anywhere for the "stale" air to go, you won't see a difference, you need ventilation such as weep vents or air bricks.

[@Noor-kp1yb]

Does the filter need changing ours isn’t working as it was before the bathroom is drenched after showers and even just washing hair over the bathtub!

[@paulfletcher7227]

I had a PIV installed a few days ago, and there no has been no condensation on my windows since

[@tomcarroll2622]

Great Video Charlie, thanks. I live in Ireland in a 1970s bungalow. We have problems with high RH and damp. I was frustrated after installing a triple glazed window that even then I was getting condensation on the inside glass! The same with all my double glazed windows. I am about to install a Drimaster PIV. I also need to take steps such as reduce the moisture from the kitchen and bathroom. I am using a De Longhi dehumidifier which works great when drying clothes etc. The more I learn and understand the less problems I am having with mold and damp!

[@h9rae]

I suffered from damp and condensation in one room downstairs ,this i found out was due to no fresh air getting into the room/ fitted 2 vents at floor level direct to the outside and one at the top, problem solved no damp no condensation , the trouble is people seal up everything to stop draught a big mistake /good video very informative

[@geoffwoollen]

Great content on the fact many people cannot understand that inside air at 20C at high RH contains more water than outside air at 5 C when its raining 100% RH. This means you should also mention :- This is why you need a water vapour barrier on the INSIDE of the walls. (VCL vapor control layer) Otherwise water vapour will penetrate into the brick and condense leading to mould inside the wall. Especially single skin walls. You cannot get at the mould inside the wall to kill it off so it will become a permanent damp and mouldy wall. Timber frame houses now use a sheet of plastic. In other words it does not want to be breathable on the INSIDE but must be breathable on the outside. If you have used polystyrene backed plasterboard thus will act as a VCL. Emulsion paints are breathable and not a VCL. So use a suitable primer or paint to establish a VCL. Builders who do not understand RH will tell you wrongly that old walls need to breathable.

[@CharlieDIYte]

Thanks Geoff. A valuable bit of commentary. Unfortunately my walls were all tyrolean rendered in the 1970s, so I'm pretty fastidious at keeping some sort of ventilation with windows open somewhere at all times. I fear some of the earlier insulated plasterboarding I did wasn't perfect from a vapour control/ cold bridging point of view but you'd be amazed how few builders understand this. I had one round recently telling me how he'd insulate the downstairs on a building project I've got planned and his vapour barrier planning was non existent.

[@axers22]

Thanks for the video. I've got a PIV without the heating element. It does make the whole house a lot colder during winter. If curtains are closed and no trickle vents are installed then it does take a while to get rid of the condensation. I've put it on a smart plug and turn it on during the days the weather is dry and wet clothing is drying. It does indeed make clothing dry faster!

[@spencerwilton5831]

axers22 a good condenser dryer is far more sensible than drying clothes on racks when line drying isn't possible. People complain about the running costs, but the advantage of a condenser dryer is that they push heat into the room which partially offsets the heat required from your boiler.

[@eternallearner4753]

I installed a Nuaire Drimaster PIV unit three years ago. In winter, the area around the unit is a little cooler, and in summer, a little warmer. There were no extractor fans fitted in my renovated cottage (now remedied), and every morning all the windows had to be severely Karchered! Now I can't even remember where I stored the Karcher. My decision to install the PIV unit was also made as it is claimed they reduce radon in a building (the cottage is in Cornwall and its walls are granite). I put the drier rack in the smallest bedroom and dry the clothes very successfully with the help of the ebac dehumidifier (I have a tumble dryer, but not the bank account to support it!). Great video, amazing research. Subscribed!

[@CharlieDIYte]

Wow, you've totally nailed the problem and you're so wise to have a dehumidifier to deal with moisture from drying the clothes. I don't have major issues here with the RH levels at a pretty constant 45 to 50% but I'm so tempted to install a PIV just to keep things circulating and to minimise condensation on the remaining, single glazed windows, as the reviews on them here are unanimously positive. Out of interest, I'm guessing you still get congregation when you shut the curtains? Thanks so much for the comment and for subscribing 👍🏻

[@geoffgeach6804]

I have recently had an Air Intake and Extraction system installed by Envirovent of Harrogate which draws air in through the Back wall of my flat and out through the front running constantly. The increase to my electricity bill is negligible but the difference in the flat is ABSOLUTELY FANBLOODYTASTIC!! I can not praise Envirovent enough.

[@jazzyman4]

In running a UPVC window and door company we issued instructions in order to keep condensation to our customers The instructions included and explanation of the amount of water we breathe out at night and the importance of ventilation when possible The UPVC windows are must more draught sealed and therefore keep the moisture in In our window we installed trickle vents at the top All the suggestions on his video are excellent and should be followed

[@Joelk2666]

Recently installed a drimaster after having condensation and mould issues. It has made the hallway colder but has cured my condensation issues

[@MurrayC]

Me too, the version without the heater. It makes the hall a little colder but that's no real hassle. RH is 50% with 90%+ outside RH.

[@ohmydog9]

Your videos have been so helpful and have taught me how to master the humidity and mould problem in my flat. We are very careful about controlling humidity like keeping the bathroom door closed - I’m always yelling at people to close the door! We are also lucky to have a window in the bathroom. Have opened all our trickle vents and automated a dehumidifier to run each night. When I see the RH sneak above 60% I open the window, even if it’s freezing, if only to ventilate for 15/30 minutes. No problems this winter! Thanks so much. Your videos on this topic are the best I found.

[@Sarhatabaot]

Perfect timing on this video. Just started looking into a mold problem we have in the room next to a shower.

[@CharlieDIYte]

Glad to hear it. Hope you find it useful!! 👍

[@andrewfallon2719]

Brilliant video for people like myself who don’t know much on the issue. I have just bought 3 hygrometers as a result of this video. If the humidity is above 60% I shall buy a window vacuum. Thank you so much

[@CharlieDIYte]

Great work Andrew. It really is half the battle actually knowing what humidity you've got. Window vac good but ventilation (opening windows) and managing all the vapour you generate cooking and bathing to make sure it doesn't circulate around the house is the most important part of this.

[@lukeferguson9010]

@@CharlieDIYte Charlie i have an ebac dehumidifier but when bedroom door is shut on a night the windows condensate up as they’re 20 years old. I tried the salt trick and it actually works. Make sure to put behind any blinds or kurtauns

[@dudleyjoseph9485]

Great video. I'm another advocate for PIV. I've got an old house which had elevated humidity levels mainly we think due to a few original flagstone floors. Mainly solid walls with minimal or no insulation also. PIV has almost completely solved condensation problems. You do need to make sure however that the source of the air in the loft space is drier than within the house and to do this, you really need to be thinking about absolute humidity levels rather than relative. The best PIV units will measure absolute humidity and turn on and off as they need to. Generally, if your loft is reasonably ventilated from outside, you should be OK. Location of the PIV is also critical. Needs to be as central as possible. Some house layouts wont work. In addition, you may need to encourage the air movement through to the rooms that are further away from the unit possibly by installing additional passive vents. Definitely need to keep doors to rooms open and ensure that the PIV is not 'short circuited' by having any existing extractor fans close to it. Yes, the air coming out of the unit can be chilly and will cool your landing down but it doesn't seem to affect the rest of the house. You would not want a unit dumping air directly into a habitable room. Go and take a look at Pete Ward's channel for a wealth of stuff about humidity in older houses and absolute vs relative discussion although he doesn't appear to be a massive fan of PIV.

[@afnankhokhar5578]

Thank you for such a detailed response. Very helpful

[@steffananthonyholden2752]

Also trim your doors 10mm from the FFL to allow free flow of air movement

[@gortagnan]

@@steffananthonyholden2752 Thanks ..makes sense but just to be sure ..FFL meaning F (?) floor level ?

[@JuiceBanger1]

final floor level. ie after you have laid the tile or lino etc. i discovered this term when installing a bath and bath panel. it just means leave a gap or shave the door to get a gap@@gortagnan

[@liberalmediabias5893]

I have an issue with extractors in general. The lower pressure gives me headaches. I know of another person who could tell the extractor in the office was on for the same reason. So extracting the humid air during a bath doesn't work for me. Also, with athsma, it feels great when you inhale steam. I just put that out there. Sometimes expressing what the obstacle is, is half way to overcoming it. Great video. Very clear. Thank you.

[@CharlieDIYte]

Sorry to hear that, mate. It's a tricky one this because I totally hear what you say about the asthma, but humidity is so bad for buildings. I guess get a couple of hygrometers and try and keep that humidity around 60% or below. Thanks for the comment 👊

[@tellylgeorge]

Great video Charlie. Very helpful and informative. I did all the same research a few years ago as I was having some issues with condensation and mould in my bungalow. I installed a good centrifugal fan in my bathroom and ducted my kitchen extractor to outside. But I also installed a PIV ( the one pictured in your video actually) and it has been great. My hygrometer rarely goes above 40 RH. I've set mine on a low fan speed which seems to change the air enough for my place and it certainly doesn't create a cold spot in my passage. When you put your hand up to the outlet you can feel the draft but this isn't enough to create a cold spot in the hallway. You can't feel any cold air when stood directly underneath the outlet. I haven't noticed any significant increase in my electricity bill from the fan in loft running constantly. When the loft temperature increases in the warmer weather the unit switches off as it is thermostatically controlled. All this said I really do think that your lifestyle habits are the main influence because you do have to manage the air inside your home as best you can. Keep up the great videos.

[@paulhillman8299]

We have had a Nuaire PIV for about 6 years. Within about 4 days after the installation, all our condensation problems disappeared. The house is old (~1900), brick and we added and amended it to 5 bedrooms for what became a large family. Damp in the walls was always a problem but since the PIV has ben installed, there is no mould or discoloured paintwork. You can hear it when on the maximum 6 setting but soon get to ignore it. In all we are very pleased with it.

[@CharlieDIYte]

Thanks Paul. Yes you and many others have extolled the virtues of PIVs in this comment feed. I'd quite like to install one here. Could be an autumn job if I get everything else done. Also presumably it provides a bit of cool air on summer nights?

[@TK42138]

Quite possibly the best condensation advice video on KZbin.

[@CharlieDIYte]

Thanks 🙏👍🏻

[@gillian417]

Not obvious. So helpful. I've spoken to several tradesman who've never offered this advice. THANK YOU and now a subscriber.

[@CharlieDIYte]

Thanks Gillian. I did an update video a few weeks ago kzbin.info/www/bejne/hJPXmp1-gN5ljNE I appreciate the sub 👍

[@johnrussell5245]

I fitted a heat recovery ventilation system in our barn conversion 18 years ago. It was the best money I ever spent. I've fitted it in other dwellings since and I'd go as far to say I'll never live in a house without MVHR again. It should be mandatory in all new builds. I've never come across a house that can't be retrofitted, with a bit of effort and the will to do it. They might cost (£4-6,000), but they're easy enough to fit by any competent DIYer. They should be a priority ahead of frivolous things like fancy cars and expensive holidays. They will improve every day of your life spent in your home.

[@rtaitm]

High praise, but how does it improve your life so much?

[@andrewstones2921]

John Russell is correct that MVHR is the answer, and having fitted it 18 years ago he was well ahead of the pack. I work with MVHR daily, but the company that work for now only install MHRV in new build houses. It's perfectly correct that with effort you can retrofit virtually any home, but to work at it's best the house should be airtight and insulated to a very high standard, and typically that's not practical in an older home. In the course of my work I have seen poorly installed MHRV by builders and well installed MHRV by DIY'er, but typically a retrofit has so many constraints on the type of ducting you can use and the optimal design layout that whilst very worthwhile and a huge benefit over not having it, it almost certainly will not approach the effectiveness achieved in a new build with an equally high standard of airtightness and insulation. The bottom line here is that all new homes SHOULD have MHRV and the cost is very low if installed at the right stage in the build.

[@dave2166]

@@rtaitm simply they continously extract the stall stagnant moisture laden air with fresh filtered and tempered air...whilst recovering upto 90% of the heat energy....24/7. They will be mandatory in new houses within 5 years id say if the government are truly serious about nett zero carbon aspirations

[@ja5837]

An excellent video on condensation, one thing that we have found living in a stone house with thick walls and built with lime is that when you live in a valley as we do the humidity outside is nearly always higher, thus making it harder to get the reading down, the way old stone and lime buildings work with thick walls is the walls absorb the wet and it dissipates it when the weather is dry, sunny or windy, we find the best way to get the inside humidity down is to coat the outside walls with a liquid sealer like water seal, what that does is allows the walls to still breath, dissipating the damp but actually seals the stone from the wet, this makes the wall drier and warmer and the inside humidity level falls. This stuff is not cheap and there are online demonstrations of how it works.

[@rpcrev]

Very timely video. Thanks for that, so insightful. And my contribution to the discussion is- We have just had a positive air pressure system fitted to the loft by our landlord. We had terrible damp problems despite doing many of the measures you outlined. So in conclusion 1) It did work. Noticeable fresher cleaner air and less damp and mould in corner bedroom. 2) sadly our smart meter has gone crazy. Maxing out in the red almost everyday compared to sometimes being under budget.. . 4 kW heater is clearly the culprit. 3) Our hallway is never particularly warm but I would say it feels a little cooler. But not substantially. So it's doing a great job but at a very noticeable cost due to the heater. Obviously, years down the line will involve servicing issues too.

[@pah9844]

Hi Charlie. I was OCD with damp windows, mould for years, drive me mad. I even changed descent windows once thinking they weren’t that good. I then saw NewAir ad for PIV and had one fitted in my loft above my stairs. Best thing ever. I’ve had it for 4 yrs and never get condensation or mould in any rooms and I live in a 4 bed detached. I bought the switch to warm the air slightly and don’t have any issues with this, maybe use to it and it doesn’t really cost anything to run. I’ve also used a dehumidifier for years to dry clothes overnight. Works wonders.

[@CharlieDIYte]

Thanks Paul. That's great to hear. Yes, I think a PIV install might be a good summer job for me!

[@Largeone1968]

Another vote for PIV. I’m a landlord and the go to solution for lifestyle damp is a PIV. Go on any landlord page and you’ll see the same answer time and time again. In the six years that I’ve been fitting them, the Nuaire have gone from £260 to just shy of £400 for the heated unit. This is no doubt due to popularity. They just work. They’re absolutely silent unlike dehumidifiers. They’re much cheaper to run than dehumidifiers too. What’s not been mentioned is they help allergy sufferers by the filtered air driving out pollen, dust and mites. I’ve had to block up certain air vents close to the Piv due to air taking the path of least resistance. Highly recommended

[@truth952]

Where do you install them? I think a PIV would be a solution to one of my rental properties which has significant damp in cellar to the point it’s recently been affecting corners in living room. Am I best to put PIV in the cellar by air brick or put it in loft ?

[@baldeepgill7916]

I completely agree we had a bad cause of condensation in our rental property and our tenants complained alot. Then, eight years ago I came across PIVs and I got a nuaire installed and I must say it has worked 100% and I also have a mr venty envirovent installed installed in ours too. Now, we have acquired a new property.. We have noticed the internal glazing is soaked in water. Will be investing in a piv here too before we get tenants in. Prevention is better than the cure. A nuaire got installed yesterday and checked it out. boy is it a bit noisy..hope it settles down. Going to ensure that within the tenancy agreement the tenants are not allowed to meddle with it.

[@dave2166]

@@truth952 they mostly go in a loft for a house... however not every house suits a piv...most do. The only true way to understand its suitability then a free survey from someone like envirovent will tell you all you need

[@andrewriley4204]

I've fitted one. Think of a PIV like the car windscreen demister. That blows air over the windscreen (basically a window) & provides a clear view without Condensation. Problem is, we add heat to the blower in cars, simply for our comfort, who wants to sit there freezing? Equally the standard NuAire PIV is a cold blown air so stairwells will be cold unless, you add the bolt-on heater or start with the model with a heat unit Cheers, Andrew

[@dave2166]

@@andrewriley4204 they should not be folded without the heater.... my company doesn't. Even though the top of the ceiling above the stairs will be the warmest air in the house youre redistributing that air and shifting it elsewhere.

[@cwiddowson1]

Wow, comprehensive with a capital 'C', thank you! We have an old French house with single glazing, solid stone walls and no damp course (there's a complete disbelief in rising damp over here). That said, the bottom 6" of virtually everything wood - stairs, skirting, door frames etc. had virtually disappeared due to rot with corresponding mould in room corners. I put this down to how the previous owners used the house for a few months then locked it up and left it for several more (over a period of 60yrs). After a couple of years of living in the house full time with a big focus on letting it 'breathe', damp does not seem to be a problem other than condensation even without any curtains. For this we've started copying our French neighbours who religiously close all external shutters at dusk. Voila, no condensation (or light for that matter). Thanks again!

[@CharlieDIYte]

Yes, closing the shutters will achieve a lot, because it's raising the temperature of the pane on the outside, meaning nothing can condense against it on the inside. Glad to hear you're getting to the bottom of it. 👍

[@markandfionastilwell2323]

Installed PIV units 6-7 years ago and our condensation problems disappeared. No issue with cold draughts or temperature. Our house is circa 1900 stone with slate roof and double glazing. Have had several family and friends install them and all have been really impressed with the difference.

[@CharlieDIYte]

Thanks Mark, yes, there's universal love for PIVs in this comments feed. I think I'll be installing one next winter (too many videos in the pipeline to do it now!)

[@brownesugar1000]

Sounds great how much did this cost please?

[@Beany87]

One thing to add which is obvious but worth pointing out to anyone still on the fence about a kartcher vac, you can use it on the bathroom tiles and shower doors to increase the efficiency of quickly lowering the humidity in the bathroom, the less standing water (close toilet lid too) the less humidity able to evaporate into the air. Great video. Looking in to reflective insulation behind my rads too :)

[@stevesmith3395]

I have had a Nuaire PIV HC unit installed and running for over a year. I can say that it absolutely transformed our excessive moisture and condensation problem within hours. I wish I had purchased the heat element one but understand they still dont warm the air up enough. I experimented a little and have found that setting three is guaranteed to stop the moisture build up and stop mould growing. This does chill the air locally somewhat when temperatures drop. Setting 2 seems to be a happy medium where you barely notice a chill and it keeps moisture down. I tried setting one but in winter you will see a small amount of condensation return in perhaps a bedroom furthest from the unit. So I an now sticking with setting 2 and will introduce a bit of ventilation to the bedroom door. I need to do a bit of work to improve the insulation around cold spots at the edges of the upstairs ceilings. I initially changed the loft insulation as excessive insulation without sufficient ventilation causes this in a lot of older houses. Just a bit of tweaking to get the balance right. This PIV unit has been vastly superior than the dehumidifier that I still have as its effects are very localised. I cant recommend a PIV unit enough and they are cheap to run. So much better for my health. I developed asthma since moving to this house. The mould used to keep appearing but does not anymore. We used to get it in wardrobes and cupboards, even downstairs there would be furry growth on boots and handbags. It was truly awful but it has been eradicated and only my sons bedroom got tiny mould spots after I experimented by leaving the unit on the lowest setting. In summer it may cut out due to high temperature. Dont worry if the temp drops again and it doesnt come on. It can be four hours or something before it comes back to life after too high a temperature.

[@baldeepgill7916]

We have a nuaire in our rental and a envirovent Mr venty in our home and going to buy a nuaire in a new rental we have acquired as it has a bad case of condensation.

[@leeholke9851]

My job is a water damage and mould restoration. And u have done ur home work well done.

[@CharlieDIYte]

Thanks Lee - I really appreciate that and it's always good to hear positive feedback from a pro!

[@barnholbol1262]

An excellent video. We're in New Zealand (emigrated 20 years ago from UK), where indoor HVAC is simply archaic; lots of uninsulated, poorly heated houses with single glazed aluminium windows. PIV is available but not compliant with ventilation regs, due to dust, allergens and even asbestos particulates present in roof spaces. Balanced pressure is much better, but requires more air tight building envelopes as well as being expensive.

[@RichardNutman]

We had an Envirovent PIV installed. The house we moved into was extremely humid, loads of mould growing on the metal window frames, and in cold corners of bedrooms. It completely solved the problem 100%. The electric it uses is minimal, few pounds a year. It does warm the air if it's cold, but it also has the effect of pushing down the warm air from radiators that collect at the top of the stairs, so the net result is it doesn't cool the house. Totally silent and no condensation on windows at all. Washed jeans even dry inside in record time! :) Our downstairs is quite open plan, so the air coming in does circulate quite well. We got the control unit with it, and after the moisture level of the house was sorted, we just run it on trickle mode now, only turn it up if we're drying several loads of clothes in the same day.

[@CharlieDIYte]

Thanks for this Richard. I'm going to install one in time for the winter. Just mulling over which manufacturer to go for but I'm interested in what you say about the Envirovent. Was there any particular reason you went for this over the Nuaire or Vent Axia?

[@RichardNutman]

@@CharlieDIYte No particular reason, it was the 1st one I saw and didn't know there were others. The model they do now is newer than the one we have, but it's still working great. Just had the filter on it changed few months ago. It can feel a little draughty at times, as our main sitting area is below the stairs where it's located, which is why we insisted on having the remote to turn it down. Normally they set it to normal and you don't get the remote. But I think the new ones integrate with a smart phone app.

[@mikes6844]

Very detailed and impressive information about condensation and mould. Ventilation, ventilation, ventilation is my mantra Charlie and yet a lot of people don’t seem to adequately ventilate their homes. I see walls running with water, no extraction and wet clothes hanging on radiators just making matters worse. The popularity of open showers doesn’t help unless extraction is done at source and left until the room is dry. One of the best and cheapest prevention methods is the use of a squeegee . Fantastic vid thanks for posting, I will be sharing with my sons . 👍🏻👍🏻👍🏻

[@StuckInTheM1ddle]

Excellent video, full of obviously well researched info that you have to put a lot of time and effort into. Don’t worry about the length, I much prefer the complete story rather than you breaking it into small chunks. My wife thought I was mad when a dehumidifier arrived recently to deal with all of the indoor clothes drying being done but she’s now an evangelist after seeing how much water it removes and how much quicker the clothes dry. Keep up the great work that saves me endless hours having to go down a rabbit-hole myself on 😀

[@CharlieDIYte]

Thanks Mark - yes this was quite a brutal one to put together, about 175 video clips in my editing folder and I still missed a couple of things!! Wise move on the dehumidifier. Did you buy it because you were having mould problems?

[@StuckInTheM1ddle]

@@CharlieDIYte I wasn't haven't mould problems in the room it's in but we have been drying a lot of clothes in the room given the time of year and I wasn't happy with all that moisture going around. I actually bought several of the Thermopro's a while back and saw how high the humidiy was getting in the room where the clothes drying is so bit the bullet and bought one. I found the below website a great resource when researching on dehumidifers and condensation in general . The guy who runs it really goes deep on his research too. www.fixmyroof.co.uk/videos-and-guides/condensation-cure/best-dehumidifier/

[@1212haro]

We gave up purchasing the larger dehumidifiers as they were only lasting us a year on average, regardless of brand name. Instead we purchased the table top models, one for each room and two for our unfinished basement. These little power houses have completely solved our high humidity problems. We hare removing 1/2 to 1 inch of water per day. One of these units is already 3 years old and still working like a charm!

[@CharlieDIYte]

Great work. Glad to hear it's solved your humidity problems👍

[@matthewgurd6477]

Great video, about two years ago we did similar research and decided on installing a nuaire PIV in the upstairs hallway. Humidity levels dropped in the problem room from +70% to 50-60%. We chose the heated PIR and did notice chilly air being pumped at the start so we do increase the heat in the winter. Electricity bills were not drastically impacted.

[@EssGeeSee]

I concur. Only run our PIV at night.

[@abutw0]

I have read that as moist airvin house, naturally rises to attic, there is a risk that that very same humid air can be pumped back into house. Similarly if attic is vented via eaves etc. Fresh air in Attic can also be very moist.... Any thoughts?

[@Coxy002605]

@@abutw0 Moisture naturally rises with warmer air to the ceiling, where it gets trapped. The fresh air coming in from outside is almost certainly of lower humidity than the air inside the house.

[@declanpboles]

The best presenter I seen in a while and knows his stuff. Well done.

[@ollydearden]

I put a PIV in last year and it's been bloody brilliant (I'll leave the manufacturer out, so you know I'm not spamming) No condensation on any window in my single glazed, 1930s house. The house also smells fresher upstairs, but not cold. The house also heats up much faster.

[@gekcho]

Hi Olly, can you tell me which brand of PIV you bought and what part of the world you live in?

[@baldeepgill7916]

We have nuaire drimaster in my rental and a envirovent Mr venty in our home..will be getting another nuaire for a rental we have acquired.. Don't want headache of complaining tenants. Kid you not it is the best investment we made.

[@alanyoung7532]

A very interesting, thorough, informative and easily to understand insight into condensation and its causes in the home. A must-view for anyone wishing to understand and act on this issue.

[@CMDRSloma]

I'm a fan of DIY Home Automation so I bought cheap Xiaomi Aqara Temp/Humidity/Pressure sensors, now I measure all of them around the house and everything is parsed to the database. In the bathroom, my fan turns on when it needs to turn on - to reduce humidity and not when you switch the light on. Sometimes it turns on by itself when there is a spike in humidity. Home Assistant is amazing for automating stuff like these but I understand this is far beyond the scope of this channel. Luckily I don't have too many problems with humidity, it stays around 40-60% in winter, the house is insulated and the windows are double glazed.

[@CharlieDIYte]

Very cool indeed. You should install this for landlords. You'd make a fortune!

[@prizecowproductionspresent4463]

As a semi retired Glazier that worked in England for 3 years i understand the problems you get in your houses. Like Mr Cooke i found this explantion on how to deal with Humidity and air flows to be spot on. The fact that i bought a house that was built nearly 70 years ago has given me the understanding of solving such issues as is always the case when old details meet new lifestyles. Once again you have proved that youtube is a wonderful research tool if you take time to find the relevant information. Aussie Jeff

[@CharlieDIYte]

Good to hear from you Aussie Jeff! I appreciate that. There's a lot of love in this comment feed for the Nuaire or Vent Axia PIVs. Totally eradicates condensation. Can you get something similar in Oz?

[@isyt1]

I live in a 1930s Scottish house and have gone through the same experiences and research as you have with similar results. Insulation and ventilation is key and we run our dehumidifier regularly, especially when cooking and drying clothes beside the wood burning stove. When showering we open windows at opposing sides of the house to flush out the moisture. Also important to fill any holes and cracks on the exterior walls that are letting water in.

[@CharlieDIYte]

Thanks - it's always good to hear enterprising solutions from people in a similar situation!

[@arronth]

We've had a Nuaire PIV unit in our house for many years. (1960s bungalow) and it has improved our winter condensation problems massively. Ours doesn't have the heating element, so it does make the hallway quite cold compared to the other rooms of the house, but as it's a hallway we don't spend much time in there, so we live with it. You make a really good point about shutting doors. For PIV units to be effective we've found that we have to keep all internal doors open at might to let air circulate, otherwise in the morning the windows are streaming with moisture.

[@CharlieDIYte]

Thanks so much for that Arron. And if you leave the doors open, the windows are totally free of condensation?

[@arronth]

@@CharlieDIYte Yep, if the doors are kept open then the windows are completely dry. The only time this isn't the case is if we happen to have a sudden dip in temperature overnight for example, then we may find a small band of condensation at the bottom of the windows.

[@karl3721]

I am an electrician and I have fitted several nu aire piv, the customers all rave about their effectiveness I would definitely put one in my house if it wasn’t for the loft conversion. The heated version is a must.

[@77superboss]

Hi Karl, I’m a landlord based in Nottingham! I’m having some condensations issues in my block of flats. Mainly the top floor flats with lofts above them. I’m considering installing one of the PIV units however have been told I may need to also run a hard wired fire alarm from the device as it will be on a top floor flat. Could you also let me know what specific PIV unit you would recommend?! Thank you! Best wishes.

[@karl3721]

@@77superboss I have used nu air, they are on the internet based in Wales

[@goosegog]

What an excellent video! I live in a 70 year old house with cold spots on the walls and persistent mould and damp problems despite having double glazing throughout and being careful to ventilate. I sneeze a lot and after cleaning the mould everywhere I could find it and running two compressor dehumidifiers in my home, I and my house are much better for it. My sneezing has massively reduced.

[@heriothandyman3148]

Well done on going the extra mile, fantastic data collection and analysis. We moved into a property with a Heat recovery system, not knowing anything about it. 2 years on, very very thankful for it.

[@63phillip]

I am in the UK and I use a desiccant dehumidifier and it works great it lets me keep my place at 50% humidity all winter long.

[@CharlieDIYte]

Glad to hear that. Good work 👍

[@hannahswann747]

Thank you so much for this incredibly helpful and informative video. I’m renovating an old stone house in Wales with soaking wet cellar walls even after removing the cement render 8 months ago. Your advice on HRV systems was a eureka moment as I didn’t know they existed so many thanks for that! 👍

[@limitless1692]

This 20 min video ... It just gave me a lifetime of experience ... Thank You Very Much Sir !!

[@CharlieDIYte]

You're very welcome. Thanks for the comment 🙏

[@simonclarke6970]

I installed a Nuair Piv unit in a rental property several years ago after regular complaints about saturated windows and mouldy clothes. It is no exaggeration to say that it solved all the problems overnight. Fitted in the loft with the outlet at the top of the stairs. small increase in electricity costs but no complaints from tenants.

[@tiggywinkle1000]

Learned a lot of useful tips from your video. Thank you. I do not have room for an electric clothes dryer, and use one of the old-fashioned 'Sheila-Maid' airers that wind down from the ceiling on pulleys. I found that more moisture was always deposited on the windows as a result. To counter it, I now set the washer to 800 RPM spin, to stop excessive machine vibration. Then at the end of this normal wash cycle, leave the clothes, etc. in the machine and set to a further 1400 RPM 'spin only' cycle. The washing comes out almost dry after this and the condensation on the windows practically eliminated.

[@jeffhalbo96]

Excellent analysis of this issue, Charlie, thank you! Our experience of dehumidifiers totally bears out your endorsement of them, especially for laundry drying but also for general control of the RH in our home.

[@charlescp1558]

It’s a while since you posted this, but I thought I would say we installed an Envirovent in my daughter’s 2 bed flat and it solved damp and mould problem overnight. Can also dry clothes on airers very quickly. No loft, so mounted above entrance door and draws air in through a hole cut in acrylic we swapped the glass out for. Fantastic product, not cheap, but works and very low running costs, was teamed with their humidistat extractor serving bathroom and kitchen. Keep up the good content!

[@frederickwood9116]

Nice work. I have obsessed about Relative Humidity values for a number of years. It’s not something that people find easy to understand. So explaining it is not always successful. I think you got it down nicely. Personally I think every house in our climate should have a dehumidifier but the concept is not widely understood. I have not played with many brands but I am a Meaco fan. I have bought both desiccant and compressor versions. My research found compressor ones seem to operate best around room temperature and the desiccant ones are best in colder spaces (15 c down to -10 or so) The desiccant ones tend to warm a room slightly which may be an advantage in some situations and can explain the extra running cost. I highly recommend a dehumidifier as a clothes drying solution in our UK / Ireland climate. You get good results for less cost than running a tumble dryer (I have seen bills drop significantly) as well as rooms/houses being healthier. The best drying results being where a largeish desk fan is also used to move air through the clothes rack even just at a slow speed. Also your don’t need to use the clothes drying setting but it will day things faster. I like the compressor dehumidifier you have there. Nice controls. I may have to try it out if I need to get another one some day. Thanks again. I’ll be sharing this when the topic comes up.

[@monevaluation4716]

Extremely useful video. Thank you. Only thing I'd add is when you cover the sciency bits, talk a bit more slowly please so I can process what you are saying before the next chunk of information. I've taken to draining boiled veg outside in the garden to avoid all that steam mixing with the indoor air in the kitchen. I always open window wide whilst showing. Open bedroom window in the morning, even if it's cold outside. Living in a 1870s house, some doors have gaps under them. Ive realised those gaps are my friends and not to get rid of them! Thank you again for your very good videos.

[@surreyarborist]

This bloke is talking a lot of sense here now subscribed

[@djm9937]

Now that was very informative. Condensation in our house has been awful this year compared to others. My heating has been on low..about 18degrees due to costs. I did not know that warmer air will hold the humidity and in turn reduce condensation. This has given me lots to think about. Thankyou so much :)

[@CharlieDIYte]

There's this update kzbin.info/www/bejne/hJPXmp1-gN5ljNEsi=1x4TpDePcC9J7AsM and if seriously consider installing a PIV in the corridor ceiling upstairs. It'll cure the issue overnight but you should investigate the steps I talk about in this vid too.

[@Smithb83]

Another excellent video Charlie, chock full of well researched info to help us homeowners overcome DIY issues. Love your channel 🙌

[@lawrenceslatter-buesnel1755]

Thank you so much for your videos. I watched both your videos on this and it’s really helped. We have changed our lifestyle habits to reduce excess condensation in the house as well as at night running a dehumidifier because we suffered with lots of condensation on our wall and windows. Massive change from 86% down to 50/60%. Thanks so much Charlie.

[@RichardsModellingAdventures]

We have a PIV unit in our bungalow. It fixed the problems we had with damp over night. No problems with cold air at all. We just run it very slow

[@DerekHundik]

piv whats that ?

[@bmatic2069]

@@DerekHundik Google PIV Ventilation - loads of information!!!

[@eastsharp]

Great video! I just bought a hundred year old house with single panes in a forest. I learned everything the hard way!

[@geoffaries]

Hi Charlie another of you excellent videos, I've been involved in heating and ventilation for more years than I care to remember, but have seldom seen the issues so well explained, it is so good that I've sent your link to the company who manage my rental properties :-) I've been giving this type of advice for some years, but not so well as you have done. There is a caveat, which concerns the optimum level of humidity, I suffer from a form of bronchitis in the winter and have found that the best humidity for me is circa 55%, my doctor suggested putting the damp washing in the bedroom! but being an engineer I elected to use a humidifier where I can accuratley control the humidity. I have found that modern well insulated properties can have humidities in the 30 - 40% range, which dries out the mucous membranes inside of humans, more serious than chapped lips! I have also been involved with the design and installation of MHVR systems and one of the problems is in maintaining them e.g. people don't clean/replace the filters regualarly and they can introduce low %RH air into the house which will reduce the house humidity. I use the Meaco in my "man cave" where my toys live, because it seems that most of the refrigerant types are not very efficient below ambient air temp. of 15 Deg.C.

[@ravi5602]

Positive Input systems - I have a rental property and the tenants are forever drying clothes on rads, under heating the property and never opening windows. This resulted in literally puddles of water on window sills and black mould growth on external walls. After trying a lot of different thing we installed a c£400 positive input device and I must say it is BRILLIANT! Totally cured the damp problems in a 4 bed double glazed 1950's student house and they pay the electricity bill. I was amazed it was so effective.

[@ravi5602]

I should add it the heated version...

[@CharlieDIYte]

Thanks Ravi. It's rental properties that feel this most acutely because you can do so much to manage humidity through lifestyle, which a lot of tenants, particularly students aren't going to be focused on (I certainly wouldn't have been back then). I'm not surprised you've found the PIV to have been so effective as I was introduced to them originally by a friend who has a couple of rental properties. What I am surprised about is where all that moisture goes. I suppose it's constantly diluted by the cold, drier air coming in, and whenever someone opens a window (rare) or front door (less rare!) the house breathes a sigh of relief and belches out some of that humid air.

[@andrewadam4989]

I've added Positive Vent systems to two of my houses and find they work very well. There is certainly a chilly spot directly underneath but I don't find that it makes the general house spacer cooler or cause me to have high heating to compensate. I used to have a dehumidifier and find that the PV system works much much better.

[@rossmanning4863]

Andrew Adam I’ve got one with a heater on it. Does the job.

[@dave2166]

Its the perception of air movement which makes you feel its colder... a fan on a hot day when its 30c will make you feel cooler even though the air passing over your skin is still 30c

[@dannygee3600]

I have an Electriq Desiccant Dehumidifier, it has a smart mode, it is excellent. I stareted at 89% Humidity, that is now down to 40%. It works very well and is not an energy guzzler as the electric heating comes on less often because the dehumidifier has warmed the room. Very pleased. The model I have has got a 6 litre tank, which I empty twice a day, generally with about 10l extracted daily. Also the water collected is great for watering plants, topping up my pond and for doing the ironing too.

[@GosforthHandyman]

Charlie - that's some serious work you've put in to that video! Awesome stuff! Fantastic video as usual. We're in a new build at the mo. and the total lack of any form of damp or condensation has been a nice change. In fact we sometimes get condensation on the outside of windows! Wouldn't surprise me in the rel. humidity was

[@chrispybus8741]

£

[@lfuentes4098]

This was very informative. I have recently notice a mildew smell in my bedroom. And found that most of my wood furniture has mildew on it. The wall to the outside is very cold. The apartment has no insulation and the apartment below us was vacant for almost two years. I think this and all the regular causes you mention increased the RH in the room. I’m shopping for de humidifiers now and I’m trying to keep the windows open in the winter as well. Thanks for the education!

[@CharlieDIYte]

Well done, those steps will make a huge difference. Here's my recent update vid kzbin.info/www/bejne/hJPXmp1-gN5ljNE 👍

[@fabmanly1070]

I you have an attic, you can install a Positive Pressure Ventilation system. How many of you run your Bathroom fan 10-15 minutes after you’ve finished? Probably very few (you need to completely cycle through an entire room of air). PPV system is like having a tube running into your house from the roof. Imagine putting a large super hose into this and pouring water down it rapidly, your house would start filling up and eventually water would find its way out through the cracks in your windows/doors as its under pressure. That’s what a Positive Pressure air system does. It will work its way through the house forcing out stale damp air. Your house needs that change of air constantly to avoid stale stagnant air. Its called cycling, and you need to work out your volume of interior living space so you can install the correctly powered system that will cycle the correct amount/volume of air for your home. Your furniture/ clothes/ lounge suite/ mattresses (can hold anything up 10 litres of water-water! Wow imagine sleeping in a bed with 10 litres of water in it!) must be purged of this moisture before you will be healthy. So the system will take a few months before you truly have a healthy home, but you will notice it after a few days with the firs at signs (no weeping on the windows). Leave cupboard doors and any spaces with closed doors ajar so air can flow. Its all about air movement and pressure.

[@markwilliams5654]

most Fans have a built in timer or humidistat

[@JayL123]

@fabmanly1070 Would we need Trickle vents on the windows for PIVs to work? None of the rooms have ventilation holes in the wall but have trickle vents in the windows. We plan to change the windows and I wonder if I have to get tricke vents in it for the air to flow. Apologies if its a silly question, but the trickle vents are all dusty and mouldy.

[@fabmanly1070]

@@JayL123 Had to look up trickle vents. We don’t have them in New Zealand. Air, like water will always find the easiest exit point. We never had any of that in my homes with PPV’s. Talk to an installer near you. We also have two positions for our handles to be positioned on our windows, so they can be left ajar if needed, but still locked. Air will always find a way out. New windows are good and bad. Good to seal, but bad because they are so good at sealing up. But as you say, you have these extra vents that sit hove your windows.

[@ezza88ster]

Very complete and informative. No need for apology regarding length of video, as far as I'm concerned. The kind of people into this are detail orientated I suspect.

[@CharlieDIYte]

Thanks. This was a quick update kzbin.info/www/bejne/hJPXmp1-gN5ljNEsi=q_A3ktsxQjdMozJB 👊

[@209porker]

We have a PIV in our 130yr old house. It is a large 3500sq ft. property with no insulation and thick walls. The condensation and RH have reduced significantly since I installed it a few years ago. I also noted the price seems to have crept up significantly. I have the heated model but never wired the heater up. I note that another well respected you tuber who posts a lot about damp issues is sceptical about PIV but I think as our roof space is well ventilated (read has loads of gaps) I think the colder dryer air in the loft is pushed through the house meaning the wetter air gets pushed out. I also insulated an exposed bedroom internally that used to suffer from condensation on parts of the walls and this has cured the problem.

[@CharlieDIYte]

Thanks Matt - that's interesting and confirms what I heard when I was researching this. The insulation makes a massive difference, doesn't it. You just have to ensure you don't create any child bridges when installing it, which I didn't completely do in my son's room. Still, he had mould everywhere before and none now. Thanks for the comment!

[@miatrue98]

What does PIV stand for? Thank you

[@fc1133]

I watch all kinds of "technical" and "how to" videos all the time, and I have to say, this is one of the best ones ever. Perfectly done! Having said that, I always wondered if you could do the following: Freeze a bunch of plastic coke bottles and place them around your house. Now instead of the water collecting on your windows, or anywhere else, it should condensate on the bottle. Place the bottle in a little container so the water can collect in it and your done. What do you think!? Thanks.

[@bockersjv]

Brilliant video. One thing you could have also mentioned it’s to keep things away from walls. Having a bed, for example, against a wall is terrible as mould will build up unseen on the wall below the bed. Even bedside tables need to fit direct to the wall with no gap or leave a space of 20mm or more. I’m still amazed at the volume of water the dehumidifier pulls on a daily basis in winter.

[@CharlieDIYte]

Very true, John. I've missed a few things out annoyingly! Only thing I'd say is that we used to massively suffer from that problem but since insulating our walls it's a thing of the past.

[@lynnfincham6839]

Mould will grow even inside plastic boxes with shoes handbags inside - nightmare

[@roncouch]

Yes, where the ‘temperature gradient’ is high ( outside temp vis-a-vis inside temp’ dew point levels are reached rapidly as one might exoect? Loved the video by the way - delivered like a seasoned H&V engineer!

[@dooovde]

Personally I chose a desiccant dehumidifier since it seems to work better in cold rooms. The amount of water that condensers pull from the air is based on the temp being 30° c. In temps less than 18°, it will put a lot less water from the air. In winter is when I’m going to want to use the dehumidifier and the rooms in my house would get down to around 12° during that period. The desiccant dehumidifier might run at around 350 watts whereas a condenser might run at 200 watts but the extra 150 watts will add heat to your cold room as well so it’s not all bad.

[@davidedwards60]

Thank you Charlie! I am an Engineer although of the Software persuasion but I still naively thought I had a decent understanding of condensation. Having watched this video (which is perfectly pitched IMO) I am a lot less complacent and much happier that I now know better.

[@andyandy3506]

Fantastic video, thanks. I've had damp problems from time to time, and had dismissed the idea of bringing in more air from outdoors, as I'd assumed it would be too damp. Completely failed to consider that the lower temperature would reduce its capacity for moisture... A couple of things to add... a very good point about the water vapour from cooking, and I've found a good kitchen extractor fan to be well worth the money spent on it. Probably not worth worrying too much about the kettle though, as despite the noise and visible vapour, an average kettle will only lose a few grams of water when it boils. Insulated plasterboard can be a good way of topping up the overall insulation in a house, but ideally needs a thorough assessment to be undertaken before it's installed. The danger with this stuff is that you're moving the hot/cold boundary away from the surface, so it sits inside the wall itself. So any water in the air can end up condensing on the cold bricks behind the boards, which can be a disaster. Worst case is you get water penetrating from outside (can happen with older non-cavity houses) as well as water vapour coming in from the inside of a house, and this all ends up running down the wall behind the plasterboard. Anyway, thanks again for posting this excellent video. I will definitely be sharing it.

[@andrewhigdon8346]

Relative humidity is a very complex value to predict. Temperature is only part of the problem. For example, winter time can be just as high of relative humidity if not higher than summer time.

[@russelldunning294]

@@andrewhigdon8346 True, it can be raining outside but it can still be fine to open a window to let in the drier(!) air. Winter is the main problem due to cold temperatures leading to condensation and mould.

[@christiea772]

The effort and detail that went into this video is much appreciated

[@caskwith]

So many videos and forums talk about this subject and get it either totally or mostly wrong. SO refreshing to see a video where somebody gets it right! A few things I would like to mention though if you don't mind. Desiccant dehumidifiers are more efficient at lower temps as you state, if you prefer a cooler house they are the best choice. A compressor type needs a higher temp will be inefficient below 20c, a desiccant will work fine and while it does cost more to run, it puts out heat as a byproduct so you get a bit of free heating at the same time as drying the air. If you can't afford to heat your house to around 20c (we can't) then a desiccant type will be more cost effective in the long run. Trickle vents. I wouldn't bother opening windows or trickle vents. While you are bring in drier air, it is also cold (with some moisture still) so your heating has to work harder and overall costs are increased. Unless your house is very modern and carefully built you will have more than enough gaps and leaks letting in fresh air so I say keep all windows and vents closed and just use the dehumidifier to keep things dry.

[@caskwith]

Oh also PIV units are a complete con and massive waste of money on a house over 20 years old unless you do thorough renovation and air sealing. The money spent will never be recovered in any savings on heating or improvements in humidity. For a new build house built with them in mind they are great but otherwise people are just wasting their money.

[@markbrown1412]

Hello, I live in interior Alaska. I am in the process of building and have the good fortune of being near the cold weather climate research center in Fairbanks. I must say, your video is spot on regarding this moisture/ventilation issue in the home. Understanding what the dew point really means cannot be Overemphasized. Your video covers these issues in a very helpful and informative way. I am a retired environmental chemist, have a good grasp of the subject matter, and have seen people insulate their homes in ways that contribute to this problem. Even though My education should make me an expert on the subject, it does not. I had to modify my home plans after consulting with the people at the cold weather research center in Fairbanks. My ideas about properly insulating my home were misguided. People get information from KZbin, their neighbors, and their friends, believing they are doing something good for their home, when in reality, they are actually making their moisture/ condensation worse. Why? Because they are getting bad/inaccurate information, and they don’t understand the concepts regarding air temperature, humidity, and dew point or relative humidity. Building practices that work in warm/hot climates probably will not work in a cold climate. I learned this upon moving to Alaska. Thank you for your well done And spot on video.

[@WisdomIsPrecious]

What specifically are the mistakes ppl make that you learned about?

[@capbin146]

As others say don’t apologise for a long video especially when it is well presented and informative. New subscriber. Now to figure out the cost benefit analysis. ps My mum and I were given advice 40 years ago when I had lots of chest infections, the gp said lots of central heated houses are too dry and recommended a bowl of water in the room to humidify the living room. Long before Amazon and those gadgets. Another mystery. Thanks

[@tomthumb2062]

Fantastic Video Charlie, we all have problems with damp/mold.. Well researched and explained. Thank you my friend 🙏🏻

[@CharlieDIYte]

You're very welcome - thanks for the comment, I really appreciate it!

[@kmw7273]

Thank you so much for your fantastic channel,only watched 2 of your videos last night, I always have problems with morning condensation esp in bathroom, in the winter always a puddle on my windowsill and mould round my windows and a new problem with condensation running off downstairs window and down the wall (small slope on sill) since I replaced open fire with stove. I was purchasing a dehumidifier which I'm going to return once I receive it and I bought the ebac one last night that you recommended. I pulled my blinds up fully going to bed in every room and cracked them open a small bit, bathroom window I opened out to the security latch, my bedroom I pulled blind up to nearly half and cracked window open a tiny bits ..and NOT ONE DROP of condensation anywhere this morning even after our very frosty night ..to say im shocked and so happy is an understatement... Thank you so so much

[@dug1001]

Great video, been looking into getting one of these PIV units myself. Reading the comments I think I definitely will. One thing to mention re your kitchen extractor hood is that it’ll only suck out the cooking moisture if it’s a proper vented out through the wall one. Some are just recirculating the air back into the room but filtering out the smells with a charcole filter, no good for reducing the moisture. Another good tip would be to boil the kettle under or next to the cooker hood with it turned on. I do this, my wife thinks I’m mad.

[@CharlieDIYte]

Good point. Mine is vented but I should have mentioned that.

[@frederickwood9116]

I find the non vented ones just hilarious. Its like a con. People see the unit and think it’s going to work. I guess they could have charcoal or something but!!

[@broadsword6650]

The non-vented hoods are grease and fume filters (and not very good ones). Better than nothing, just.

[@matserrien6271]

Compete and exhaustive explanations. Nice video that opened my eyes and broaden my knowledge on my humidity problems. I'm now back on rails to solve them all ... at once.

[@bucklesmagee3806]

Living in an older property I never knew like a cave it traps the moisture well. Thanks for this 👍👍

[@tapeslayersreviewsreviews9807]

Can you tell if the walls are lime plastered or cement or gypsum

[@sibat777]

On the Kettle front, I’ve bought one of those units that just boils one cup of water at a time, it reduces the steam in the kitchen dramatically. The reservoir only needs refilling 6-8 cups of tea or coffer (and it filters the water too). It’s quicker than boiling the whole kettle for one or two cups too!

[@CharlieDIYte]

That's really interesting. Which one is it, out of interest?

[@sibat777]

@@CharlieDIYte this is the one I bought, there are many others but this one balances price with quality well imho www.amazon.co.uk/gp/product/B002NGNRHC/ref=ppx_yo_dt_b_asin_title_o09_s00?ie=UTF8&psc=1

[@CharlieDIYte]

@@sibat777 Thanks! I'll be buying one of these. I wouldn't have known it existed without you so thank you for that 👍

[@sibat777]

@@CharlieDIYte 👍 good luck, I did think about the Quooker instant hot water tap but that was too expensive, same concept but no need to refill.🧐

[@jotttn]

Sibat 777 - that’s fantastic! This is just what I have been looking for

[@InspiredByBrad]

Cling / shrink film can seal the glass from the air just like dual pane glass, and stop condensation and increase thermal efficiency. Easily applied and removed each season.

[@pavel9652]

I was thinking about it, but I don't think it will stop the condensation, unless it is dedicated product and the condensation isn't too bad.

[@deftouch]

This was a fantastic video Charlie, and so informative and interesting that I wouldn't have minded if it went on another 25 minutes. Love your videos, thanks a million.

[@CharlieDIYte]

Thanks David, I really appreciate that, and it's quite timely as I'm working on a smart heating install right now and in spite of my best efforts it's 23 minutes long already with another 5 minutes to go...

[@Viewer765]

@@CharlieDIYte how long did smart mode on your dehumidifier run for the first time before it started shutting off mine seems to run constantly and when do you have your running for