WHY DID WE NEED THIS EXPENSIVE FAN? - DIY MVHR Install 💨

With airtightness comes great responsibility! 😂 With a well insulated and airtight home more thought needs to be put into air quality. While a larger central system will make sense on the main house build, a retro fit type MVHR unit was what we opted for on the cabin.
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#mvhr #airtightness #ventilation

[@jmssun]

I seriously thought you were going to DIY this fan, as making one from scratch 😂

[@bockersjv]

For the external vent for the cooker extractor. It will massively help with the build up of oil and grease that the charcoal filters will miss. Learnt this the hard way. You can never have too much external extraction in what will be a busy kitchen area. Loving your videos and good to see another cabin update.

[@TheRestorationCouple]

Yeah agreed. I have now found an airtight anti back draft unit so will duct it out soon.

[@spongefactory]

@@TheRestorationCouple Interested in that unit Tim, can you post the details?

[@kip8790]

I have a vortice promoteo whole house unit, works great, bought it 10 years ago, totally changed my cob cottage for the better. No more damp and much warmer.

[@JasGawera]

I built an almost identical bed last week, also 2nd hand with no instructions. Mine has the ladder at one end and a pull-out desk thing at the other. Only 1 missing barrel nut. After a quick tweak with the angle grinder it fit perfectly :)

[@ashbury444]

I put a single Blauberg Vento unit in my highly insulated garden office. Doesn't need to be installed in pairs and the wall thickness is adjustable. These seems similar, but way more expensive. After three seasons use, I'm happy with it, although the app control side of it is a bit lame.

[@54mgtf22]

Hey Tim. Love your work 👍

[@charles-h9e]

BSK zephyr turkish manufacturer for circa 200 quid each! 21 l/s i think on high. 150mm fan quiet on low

[@charles-h9e]

Humidity switched target settings (40/60/80%) - 3 main settings plus a quiet low flow night mode

[@dsgg5714]

@@charles-h9e it's loud on 2nd and 3rs lvl. I do not recommend it, maybe only in rooms in basement, that aren't used a lot.

[@bobfish7699]

Excellent Video. Didn't know these existed. This is just what I am looking for when I come to rejig the kitchen and end up with an non-ducted ceiling mounted extractor above the hob. I can use on of these on the outside wall in pace of ducting across on Open ceiling. Blxxdy expensive though!

[@georgeanastasi7729]

Kair, envirovent and vent axia all do cheaper single roomvhr options but a lot of them are quite a bit uglier than this. There are also single room loft mounted units. Did post a comment with links but it's disappeared!

[@bobfish7699]

@@georgeanastasi7729 Thanks for the info George. I'll take a look.

[@TheRestorationCouple]

I’ll see if I can find and approve the links. Cheers. 👍

[@impamiizgraa]

Great video. I am a bit torn - I have spent 3 years living in a new build with MVHR, I found it to be excellent. Very low heating costs (though I needed portable air con in summer...), no condensation ever and fresh air all year around even when I dried clothes indoors. I am now moving to an 1890s Victorian house, and will add a modern extension (thick wall, floor and roof insulation, triple glazing, breathable membranes etc) top and bottom - so wondering if having half the house 'drafty' means I don't need to fit MVHR?

[@gingerelvis]

Great shout on landlords fitting something like this Tim. As many shoddy landlords as there are out there a lot of tenants don't help themselves by not opening windows regularly and drying washing inside alongside all of the other moisture producing things we do. I knew it was going to be pricey (I was thinking £400/£500) but when you told us the price and the ambiguity of quality I nearly fell of my chair!

[@northeastcorals]

MUCH cheaper units are available if you can live without app controls etc

[@gingerelvis]

@@northeastcorals I'm really not a fan of app controlled stuff. If the company disappears or stops supporting the app you can be a bit stuck.

[@northeastcorals]

@@gingerelvis Personally I think it is quite unnecessary for these types of units anyway. Most run at around 3 watts an hour on trickle mode so you can just set them to run 24/7 during the winter & if thats not enough most have a boost mode which uses a bit more power but they are still very efficient. Thats what I do anyway.

[@Mitch06102]

Hello, this was an interesting watch as I’ll be starting a new job next week as an MVHR designer and will be learning all about it

[@davideyres955]

Put your learnings up on KZbin. Great way to earn extra cash and if you are going to run your own company great advertising.

[@EightBitTony]

Glad it's not just me having large diameter hole saws almost rip my arm off ;) Put two 100mm holes in the shed, first one was a bit of a shock!

[@klausbrinck2137]

Units like that are tiny, decentral and cheap, but only have a heat-recovery-efficiency of just 90% (the big expencive ones have 98%+ ...!!!). If you dont mind aesthetics, you can put 2 of the ceramic-core-cylinders in series, that then makes: 90% + 10%*90% = 98 / 99% heat-recovery-efficiency (probably a slight bit less, cause of flow-loses, since the narrow ceramic-channels now have double the length).

[@Jackzuk]

Great vid, really interested in this subject. Are you going to post on socials or utube on how you dealt with the exposed end outside?

[@ewanp1396]

How is it working out for you? I'm thinking of getting one to solve high humidity in our bedroom which is at the end of a corridor in our bungalow so gets no air circulation. Not sure i'm brave enough to core drill the wall tho, so might get a man in to do that bit!

[@AndrewLumsden]

👍👏 In the follow-up video, show us what it looks like on the outside!

[@TheRestorationCouple]

Will do, might make me finish the cladding!

[@craigwall4195]

Hi, great video as always. I'm looking at a mhhr for my holiday let. We have an issue with mould. I have considered a centralised system as its a bungalow but this is very costly. Wondering if two decentralised units would be better. Why did you go for the Prana unit over something like a blauberg? The Prana are about double the cost and wondered what the advantages were? Thanks

[@aesopshair6690]

Might be a misunderstanding of ventilation, but extract systems seem to "throw the baby out with the bathwater" - even MVHR has limited efficiency when the flow rates are high, resulting in considerable cooling of indoor air temperature over time (at 80% efficiency and 1 air change per hour, it would take 3 hours to halve the temperature, assuming no additional heating). When the primary issue is reducing humidity a more effective solution would be a dehumidifier (which can even add heat through heat pump principle), but there don't seem to be many solutions providing discrete/built in dehumidifiers that circulate internal air. Obviously internal air quality is a substantial consideration, but with effective air circulation and humidity control, the staleness is reduced, requiring less external air to be input; it would be interesting to see how often the fan is required for humidity and how often it is activated for CO2/VOC's?

[@johnhunter4181]

Imagine everyone in the house vaping all day long - that's what CO2 would look like if you could see it and that is the main purpose of MVHR, not humidity. CO2 sensors are pretty cheap nowadays - you should get one. My MVHR is rated at 93% efficient, somewhat better than trickle vents, cat flaps and letterboxes!

[@concalma75]

What will happen if there is a fire. Does the venting switch off automatically?

[@Zakktera]

Great video!!! What kind of ceiling did you say the blue one was?? Never seen one like that before!! Really interested In sealing my home up.

[@colinoconnor4628]

What is the noise like in the bedroom unit. considering something similar for 4 bedrooms, 2 small living rooms and kitcehn dining room, not to concerned about low level noise in the living areas but wondering if its noticable in night mode in bedrooms

[@Jackzuk]

Did u do a follow up to this Tim? Could you sleeve it into a plastic pipe rather than box around it on the outside or do you need something solid to fix the outer vent on

[@HubbHubbs]

Crazy price! I just fitted an envirovent heatsava I got for £30, works really well, cant believe the price they charge for these sort of things. Probably take over 10 years to pay for itself in heat savings.

[@Jackzuk]

How du manage to pick one up for £30

[@gregcope5565]

Interesting video. Seems like a decent unit with some minor flaws (the surround / wire issue). I have retrofitted a whole house MVHR. Was an interesting project! Works really well and the house is noticeably less damp and the humistat data shows this. If yours monitors PM2.5, Chemicals or CO2 you will notice it detects cooking esp Toasting, frying or having the oven on which in my experience kick out allot of PM2.5 that the MVHR then gets rid of. Check the filters often (esp initially). You will be surprised at how much they pick up both from outside or inside. Our MVHR helps reduce hay-fever symptoms as it has a decent filter which is nearly HEPA level (not quiet). We change/wash ours every eight weeks. The preheat function is stop the heat exchanger freezing when the outside temp is well below freezing (eg -10C or below), otherwise the condensate drain can freeze and frost can damage / block the heat exchanger. Does it have a night time mode? Also can you set the boost mode? We upped ours to 90% so that when it needs to dump, it can do so quickly. Otherwise its silent. If it goes into boost mode, you can hear a gentle hum in some rooms for a minute or two. Most people cannot hear or notice it.

[@TheRestorationCouple]

Yeah that’s right, might mode and quiet auto mode. Like you say we found auto mode can be triggered by random things causing high VOC. we got really worried at one point as it was crazy high and couldn’t work out why fan was ramping up. Turns out that cut flowers and a fruit bowl full of bananas below it was triggering high levels! So not dangerous offgasing materials that we feared. 😂

[@joeb1642]

I wondered what you were going to do for ventelation when you put so much effort into insulating and making airtight. I'm currently in the process of installing a ducted MVHR system for the whole house. All the basic kit cost less then 1k but requires much more effort running ducts, boxing in and insulating the ducts etc.

[@TheRestorationCouple]

We will be going a similar route next year so lots of research to be done. It will be a huge system to spec so really need to design the ducting and room layouts at same point.

[@garyharrisonuk]

Oooo You have my attention... What did you buy? Where from? Thanks

[@joeb1642]

It was from ventelation megastore. Believe its imported from China. Not sure how good it is yet but the efficency and performance specs look good.

[@jw87240]

can i install this in my bathroom?

[@MatthewBayard]

How'd is getting on ?

[@fiveminuteman]

Can mvhr be fitted above a shower enclosure in the ceiling?

[@davideyres955]

Yes but you have to remember that you are pulling out very humid air so if you are ducting that through any area that will be cold you will have an issue with condensation in the duct. It’s important to insulate that duct well.

[@MAMDAVEM]

I installed the Marley Menv180 heat recovery unit at about £4-500 a unit.

[@colinoconnor4628]

Any good? there is a supplier near me supplying ASPIRA ECOCOMFORT RF single room HR, i was thinking of getting 7, 4 for the bedrooms, living room, dining room and small office. have open wall vents already which just trickle in and our air ad hoc , pure useless really.

[@richardstevenson2727]

👍

[@fiveminuteman]

Any problems with the fan sucking in smoke from your woodburner? We have a piv in a bungalow and when the woodburner is on it can pull in smoke that rolls down the bungalow roof. Our bungalow is modern so well sealed and when the woodburner is on if the kitchen extractor is put on air is drawn down the flue😀

[@TheRestorationCouple]

Any stove we fit will be room sealed so external air supply. Did that last time and worked great.

[@jerseyman99]

Won't this product be balanced ir it is putting as much flow in as it is taking out so smoke "should" not be an issue?

[@wilyc0y0te]

I live in an area where log burners are quite popular and in autumn/winter, you can smell the smoke outside. Won’t one of these units pull in the smoke? 🤔

[@marcosscriven]

I really don't think these single-fan systems that flip-flop between expelling and intaking air can be anywhere near as efficient as they claim. In the expelling phase, sure they can warm-up some mass, which then warms up air on the intake phase. But there's two issues - on the very short run, there's really not enough surface to properly exchange the heat. But the bigger problem is during the expelling phase, you're drawing in cold air from outside. If you weren't, you'd be creating a vacuum. So you're still then having to re-heat that air you've drawn in while your heat-recovery unit was throwing air out of the window.

[@craigwilliams6734]

Tim! I nearly fell off my chair when you said the cost!! OMG

[@user-eb8ld6kn8t]

How is this performing 3mths in?

[@livingoffgridinscotland]

So do you need one for each room or can one fan do multiple rooms?

[@TheRestorationCouple]

Depends on airflow between the rooms. It does 60m2+ so two will do the whole house. In a full house install we will do duct system I think.

[@livingoffgridinscotland]

@@TheRestorationCouple our build is one room 50 sq metres downstairs and 2 bed and bathroom upstairs…. Obviously could put vent holes between rooms upstairs?

[@TheRestorationCouple]

@@livingoffgridinscotland that’s how I think we will do our second unit here. The kids bedrooms are usually always open anyway but a small vent above doors or in wall will work. We are putting it in the hall and buying a longer duct so it’s central.

[@livingoffgridinscotland]

@@TheRestorationCouple that makes sense putting it in the hallway A lot of council houses had air vents above bedroom doors, I presume for air flow… as do some static caravans

[@TheRestorationCouple]

@@livingoffgridinscotland for building control in a dwelling, if no trickle vents are fitted then mechanical ventilation is required in every room. It may be that the vent above door option would satisfy though. For our situation I think it should be fine to it’s a central vent.

[@TheCSTutor]

Interesting to hear the review, a bit dubious of the whole heat exchanger pulling and pushing in one unit idea, does it do this at the same time or in a cycle? Also noticed that the remote looks very similar to those for the old now TV aka Roku set top boxes. So wouldn't be surprised if the "intelligence" and app is running off Roku software of sorts.

[@dsgg5714]

it does at the same time (there are 2 seperate canals inside with the same heat recovery)

[@AC-gm6bq]

Bonkers price! Other units available at a third of the price! Plus, awful customer service. Imagine when it breaks!!

[@zororat]

Any recommendations? I'm trying to find real reviews of these things, never actually seen one in person or heard of anyone with one

[@phredka12]

​@@zororat yea a have prana, actually after 16 months i return all 7 units of that garbage, as well cheaper units with ceramic heat exchanger are garbage also. Now I have central unit for 350m2 house for 600$ with pipe installation for 400$ which i made by my self in 2 days and iam impressed of huge difference. Plus all is integrated with home assistant

[@inh415]

So when this fan is extracting, the property will be at a slightly negative pressure, causing cold air to enter by any leaks. when the fan reverses it will bring in fresh air, causing an equil amount of your allready warm air to be pushed out of the property by any leaks. Feel that a 2 fan system will be significantly more efficient. Are there any decentralised systems that also do humidity control - imo the main reason to install a MVHR - no good bringing damp air in to the property when its humid out.

[@TheRestorationCouple]

The two fans are simultaneously running so should not be any noticeable change when set to equal power. While we didn't pressure test this time, it was pretty thorough detailing of airtightnesss layer so not enough to cause efficiency issues. We will monitor levels through the app more as we close things up nearer winter. For now we are just using it to boost extraction when needed.

[@inh415]

@@TheRestorationCouple oh that makes a bit more sense - I think I was reading about another one that just alter ates the airflow direction every 30min or so.

[@dorsetengineering]

@@inh415some do simultaneous supply/extract, others change direction. I’ve done a list on buildhub for those who geek out on this sort of thing

[@ice4142]

In the winter the air outside is drier than inside. Cold air holds less moisture. PIVs work by pushing cold dry air into homes in the winter. The issue is warm moist air inside condensing on cold surfaces. In the summer when humidity might be a bit higher outside the ambient temp is above the dew point so no issues there.

[@garyharrisonuk]

Have you got a link to the BuildHub page. Thanks

[@jason_ball]

Great video but personally I go for a model that is locally available. Plenty of options and about half that price.

[@TheRestorationCouple]

Any suggestions that are true DMVHR? Looking at a second one for the other end

[@jerseyman99]

@@TheRestorationCouple vent Axia has a range of similar models under the Lo Carbon brand perhaps not as sophisticated as this but MUCH lower cost I have the Tempra which claims up to 78% heart recovery, although the "claims" part makes that pretty meaningless. It was not really possible to gauge its effectiveness as I could not think of a way of measuring it.

[@jammiedude]

Just 3d printed a version of this.

[@user-pk1uy3vb6h]

Currently for sale at £625 plus vat from Ecostream in Surret

[@dsgg5714]

In Ukraine this model costs about 13k UAH = 280 GBP.

[@frankiepitt9135]

As long as you’ve got money to burn, it’s worth a try.

[@dsgg5714]

you will save money on heating if you use MVHR

[@romurphy9606]

How is this unit working out for you btw?

[@TheRestorationCouple]

Its done a great job so far. Enough for the open plan area but probably need another for the other end of the building.

[@andyedwards6124]

£1000!!! I think I'll just crack a window

[@lukeh3020]

Then you’re sending air you’ve just heated out the window and undermining your efforts to insulate and air tighten the house. I agree it sounds painful but it’s got to be worthwhile in the context of a house build.

[@jrisner6535]

There are cheaper versions, worth it for air quality & savings on bills

[@Irilia_neko]

​@@jrisner6535140$ is a way more reasonable price, but you are supposed to have one by room, not one for all the house 😅

[@antoinelegoux2288]

Look how folks are doing on the continent :-) like Frenchies! It is much cheaper too…

[@antoinelegoux2288]

I looked at retrofitting this kind of big box in the attic in my 1920’s house in London, but it is not easy. I got lost in the details of fire barriers between rooms etc… I went to permanent extractor fan in bathroom, humidity controlled trickle vents and the same as you install, in our kitchen

[@frederickwood9116]

I can’t get my head past the issue of throwing warmth out through a hole in the wall. Even with an efficient MVHR. Why not use a dehumidifier and possibly one small MVHR just to refresh the air if you don’t have air leaks? The maths are not something I’m familiar with though.

[@northeastcorals]

I don't know about this particular unit but I have several MHRUs sized for a few average rooms & usually they run at around 3 watts per hour on trickle mode or 12 watts per hour on boost. I also have x2 dehumidifiers that are adequate for 1 or 2 average sized rooms & they run at 150 watts per hour. When running in winter you should take into account that the dehumidifiers also create heat rather than loose any heat, however even when accounting for this the electricity usage difference is very significant.

[@drc6940]

Jeez. I can’t get over the price. I think that it would have been overpriced if you told me it was half the cost that you said.

[@dsgg5714]

In Ukraine these costs about 13k UAH = 280 GBP.

[@alanrobins]

Sorry but you can’t have 2 fans operating in Oposite flows 1 will stall it must have the ducting split so 1 half does in the other out

[@TheRestorationCouple]

It is two separate ducted channels inside with heat exchanger between.

[@vipjesus]

Jesus £1000 I had seen others around £500, I was expecting you to say about £300 for that thing, Can you do a follow up? Your only a few hundred away from a Toshiba air to air heat pump

[@ianroughley1933]

What does it look like from the outside? I'm in a 1800's house and for me that thing sticking out by a foot or so is a no no!

[@TheRestorationCouple]

1800s probably means your wall will hide the whole duct. It’s just a black vent. Will be in a future cladding video.

[@ice4142]

People in old homes have success with positive input ventilation (PIV) units

[@TheRestorationCouple]

@@ice4142 yeah unless you have an airtight old house which is unlikely them MVHR is not the only answer, you can embrace the leaks and use PIV but I would be concerned about pushing that air to cold spots you don’t want it. Perhaps this unit is a bit lower risk especially when paired up with some draught proofing. 🤷‍♂️

[@ice4142]

@@TheRestorationCouple I doubt the 1800s house is airtight. It's important to remember that the cold air from outside/in your loft during winter contains less moisture than the warm air in your house. You get condensation from warm moist air on cold surfaces. Diluting the warm moist air in your house with relatively drier air from outside will lower the relative humidity of the air on your house and reduce the amount of condensation you get inside. If your worried about adding a bit of cold air to your house remember that moist air is harder to heat so by reducing the humidity on your house your heating will be more efficient and the two effects will some what balance