BOILER KEEPS LOSING PRESSURE - WHY AND HOW TO FIX - Plumbing tips

[@plumberparts]

Please consider subscribing - Uploading still today! *Please Follow my Vlog, TimesWithJames* kzbin.info *PLUMBERPARTS AMAZON TOOL SHOP* www.amazon.co.uk/shop/plumberparts

[@user-ns7vj4tz5h]

My hot water pressure is very low. I have checked in all the taps and also the boiler pressure gauge pipe is not working. Normally it makes sound when i fill up the pressure but this time it's not making any sound so it means the water is not going into boiler. Please advice me. Thank you.

[@tudormorgan3762]

P

[@patrikgora4791]

++

[@lemsdarkapprentice2535]

loads of thanks for this. my boiler keeps losing pressure. it's a new boiler, so i know it's not that. but my bathroom radiator valve (not a modern rtv, just a knob) leaks and goes cold after a time, even when heating is still on. might it be this causing the loss of pressure? and do you have any videos about how to change it to a new rtv? [el'sda2].

[@IamSparticus2]

@Maximus Hamza what are you saying, we should all hack your girlfriends account ?

[@GIBLETTS]

I am actually a plumber who is 63 , so our young friend is great for me to keep constantly updated ,, plus he is a really nice guy , thanks for sharing your knowledge , I can see you are going a long way ,,

[@plumberparts]

Thanks man!

[@adamtannock]

Another tip for combi boiler pressure drops. After trying all the above, if you’re still getting a drop you can fit 2 isolation valves under the boiler on the flow and return. Isolate this for 2 days and check pressure after. If it drops then it’s the boiler, if it holds and then drops after you open valves then it’s the pipe work.

[@SkillBuilder]

Why so many hates? A quarter of a million views means that a lot of plumbers have probably lost a lot of money, but the sad fact is that a lot of plumbers aren't great at fault finding. I have been out to jobs where they have had three or four plumbers in and none of them have noticed that the pump has been fitted the wrong way round or something equally simple.

[@plumberparts]

Yeah, I'm sure it's grumpy plumbers! Hey I'm a plumber so I know how grumpy we get!

[@nukacola3795]

Plumbers didnt lose a penny from this as THEY CANT LOSE MONEY THAT WAS NEVER GOING TO THEM! see how money loss works now.

[@pomzmetaldetecting1618]

A little knowledge can be dangerous, I could roll off 101 reasons why the general public should not follow out just some of the simple task in this video such as he recommends turning the pump speed down with no future content as what else could go wrong following that simple action like leading to the boiler overheating and in extreme cases split the heat exchanger, then your in a world of pain an see how you saved money by not calling a professional🙀

[@williammcgrattan9583]

Don't get myself? It's a helpful video

[@SHANUSHAH]

@@plumberparts You mate are very Honest Plumber, good on you.

[@Tonka-os9lt]

Best video on boiler problems out there. Well done and thanks. You have helped me understand my problem comprehensively and it cost me nothing. Thanks again!

[@jcrego]

I always find these videos extremely helpful. Was losing pressure, looked around and found o ring on magnetic filter was seeping. Opened filter cleaned it out (really horrible job) and replaced o ring with a new one. Pressure remains constant. Thank you very much!

[@isaacsharp3886]

Currently working towards my nvq level 3 in plumbing and gas safe . Your videos help me a lot , thanks

[@sinbadcleo]

Thanks for that clear explanation. I 'stumbled on' this vid not quite a week after I'd called out a tech-specialist plumber (Warranty Ts&Cs ) who found 'zackly what you described - a deflated pressure expansion 'balloon' and a gushing px. release valve hidden low down behind some spare bricks. Less than 5 minutes to diagnose, 20 minutes to service in and out..... and on his way. I really like it when a skilled pro works fast and right, like that.

[@kelvinedwards5365]

I have been a breakdown engineer for 40+ years and a friend has a flat in london and was being conned . instead of writing out all of the possible reasons for constantly topping up the system i pointed her to this video...very good... i might look at your other videos now...lol

[@John-ob7dh]

You can keep these new fangled boilers.ours was fitted in 67 .ideal stnd 40/ 60 boiler.floor standing.serviced every year. All its ever had fitted is one new gas valve ( 20 years ago ) i thermo couple ( 15 years ago ) and 1 new pump. Big detached house ,10 rads .even on coldest days we don't need heating on high.It never let's us down .As the last fitter said on its service .They don't make them like this anymore .I have all the spares ( only 3 spares) .gas valve ,thermo links ,thermostat assembly.no fancy electrics.No messing around adjusting pressure. Fingers crossed it will keep going as its only been here 54 years.lol

[@annewilliams7280]

I have spent all day trying to fix this, online, phoning plumbers, getting baffled. I thought a picture of the valves might help, so spent more time online - then - I happened on this. IT IS BRILLIANT, a simple demo was all I needed. Thankyou ( one cold shower was quite enough)

[@corinthh11]

We moved in to a brand new built house and for 16 years we had pressure drops in the heating .we had all the floors lifted multiple times looking for a leak but not could be found .the pressure drops always seemed random more in the winter and less in the summer ,in the end we just kept topping it up with the housing association permission about once or twice a month. At the beginning of Dec 2021 the pressure started dropping twice or more a day.however this time i could see and hear something not right in the kitchen steam was coming out from just under the boiler where the pipes where .on investigation i found a leak where the condensation pipe was touching the heating return pipe the acidity in the water had caused a small leak and water was squirting out it was very hard to see at first as the condensation pipe was covering the leak and was dripping from the pipe lower down .when i moved the condensation pipe the leak was obvious and the pipe had corroded to the point a pin hole leak could be seen this was obviously a job for the plumper who would not be able to get out this the morning .it was very cold and we needed the heating on over night and being a ex Rn marine engineer i decided to put a patch on it with some rubber and a pair of hose clips. this in when i noticed that as i manoeuvred the rubber and hose clamps and the pipe moved water would also squirt out of the elbow joint connected to the pipe, if i stopped putting a slight strain on the pipe the squirt stopped even though the system was pressurised .in the morning the plumber came out and spent most of the morning replacing the pipe that had corroded and i had mentioned to him about the elbow joint and that i though this was the cause of the pressure leaks we had lived with so long .after he had removed the pipes and fitted the new ones i noticed on inspection of the joint that they was NO solder around the back side of the pipe and they was a clear gap between the two components/joint and looked like it had been soldered by a monkey. they had been no evidence of a leak at this joint before hand and i suspect the very very small leak and the water that had come out had evaporated on the hot pipe condensed on the condensation pipe the before causing any noticeable damage and eventually rotted the return pipe e you would expect from a leak,coupled with the fact the very small place the pipes where located where under the kitchen units and where the pipes came from under the floor part of the floor was missing to allow the pipes to come up so any water damage was beneath where you could see without removing the units and floor.since the repair our pressure has not dropped once.bad plumbing is a nightmare to figure out especially when the joints are hard to see one tip i could give is wrap newspaper round any joint you suspect as when it gets wet it is easy to see the effect on the newspaper (trick i learned from my dad)

[@swabs7004]

I cannot understand why this video has so many dislikes, I have read numerous forum posts about pressure drops on boilers and none of them are as comprehensive as this video. This video fully explained to me the various reasons for pressure drop and the cut away expansion vessel was great. Loved the video . Thanks

[@plumberparts]

I honestly don't get it either. It's probably tossers! SUBSCRIBE! ➡️👉 kzbin.info 👈⬅️if you haven't already!

[@garethsharp4039]

Great video, thanks for posting. Used the bike pump trick to add a bit of air into the expansion vessel as it had been dropping pressure, and had gone through the other trouble shooting. Hopefully it'll get the boiler through the winter. It's on borrowed time to be fair, but not in a rush to replace it! Thanks again!

[@m.f.b7144]

Thank you for a thorough explanation. I’m having a pressure loss on my boiler and keep topping up twice a day so I can get hot water and heating. I had about 3 plumbers from BGas, I’m insured with them, coming over to my house and none of them did a thorough check. The first one, balanced the radiators and left. Water pressure still low, next engineer came over looked at the water pressure gauge and left (I had just refilled it). Third one recharged the expansion vessel and said boiler needs to be taken down to repair completely. At this point, after 5 weeks of engineers missing appointments and other engineers hardly looking at the boiler itself, the problem hasn’t been solved. I have taken notes from this video and next time I shall prompt the engineers to check on these points you mentioned before they leave an unsolved job. Thank you!

[@lindaj5492]

I’m covered with same company: had three visits on consecutive days trying to fix pressure drop. On last visit, engineer was about to order new expansion vessel but found water stain on ceiling in a walk-in cupboard where there was no radiator. He’d already checked visible pipes & rads for leaks; glad he had a hunch to open that door! Stayed on another two hours to replace failed plastic T-joint, despite being soaked from the puddle above ceiling.

[@RD-ox3ce]

Don’t let those BG cowboys near your system. Most are 6 week wonders and don’t have a clue

[@fardellp]

Nice presentation and good advice. Worth pointing out though that the expansion vessel air pressure (1 to 1.2 Bar) is normally quoted for COLD condition. It shouldn't be pumped up and the pressure measured when the water is hot.

[@dhiruparmar8908]

Hi My boiler pressure is just above bar 1 in the mornings and when boiler is on it goes up to just under bar 2 range. Could you please advice is this normal. Thank you.

[@mr.dahliaking.202]

My neighbor recommended me for her friend, because she had a problem of her gas boiler mysteriously loosing pressure. On Sunday I will go there and check, maybe I will be able to fix it. Gosh, I haven't had many chances to work on heating systems, except in my own house, witch has become now sorta like my own learning grounds. Well, if there is a simple leak on system, or if there is simply bad vessel of Relief vale, I might as well get lucky. I'm learning everyday. I'm surprised that a middle aged woman is confident in 19 yo self thought plumber wannabe, in fixing her boiler. This video is going to be my guide. thanks a lot James.

[@fardellp]

Another point - the PRV can develope a leaking seat, as it is contact with acidic/particle/general muck from the primary boiler water. This can be especially prevalent where the PRV has actuated due to over-pressure. When the pressure has reduced and the valve closes again, bits of grit are left on the valve seat which can fail to seal properly leading to a permanent dribble.

[@stevenmcfarlane8831]

Not a plumber just someone that has to frequently top up the filling loop. Two plumbers have attempted to fix / replace expansion vessel. Thank you for your thorough explanation.

[@ColinWatters]

Once a Pressure Relief Valve has been forced open (perhaps by a faulty expansion vessel) they frequently start leaking or opening at a lower pressure. So if you have a faulty expansion vessel that causes the PRV to open consider replacing the PRV at the same time. Not always necessary but they aren't very expensive and might save you another drive to the plumbers merchant.

[@bruceseaman6592]

BANG ON

[@TheMerlin672]

That is very good advice.

[@Goodchappy]

Excellent video. Videos like this educate people so that when they get a tradesman in they are more clued up and far less likely to get told a load of rubbish.

[@stardust5397]

Explains it so clearly even I can understand it ! I had a new Combi installed 3 months ago & I’ve had to top it every couple of weeks - CH Engineer said it would settle - it hasn’t . Ive now good a good idea of what the problem is as overflow pipe outside is constantly dripping & so rather than feeling the Engineer is speaking to me in a foreign language I can have a more informed conversation with him - & that’s why the 3m dislikes as the old school cast iron boilers with a life span of 20 /30 years with occasional repairs have been replaced by boilers with umpteen plastic components, built in obsolescence & the creation of a whole new £££m industry to teach & test Heating Engineers who then go on to charge £££ to install , service & repair the dam things. They might be more efficient but I reckon these additional costs more than outweigh any savings on my gas bill

[@rojhasan548]

Thanks, very insightful video. One comment though, pump cavitation occurs in the low pressure (usually vacuum) region at the eye of the impeller when the pump inlet pressure is too low. Due to the low pressure environment, the water's boiling temperature is much lower and what happens is that water changes phase into vapour, rather than the impeller splitting the water and air molecules. So instead.of water boiling at 100degC ( at sea level pressure) at the eye of the impeller it could be boiling at 40degC or even 25degC. Anyway once this cavitating flow enters the exit of the impeller its is represurised to due gaining the spinning work from the impeller and you will hear the vapour bubbles pop and burst letting out tiny acoustic waves that start to damage and grind away the impeller blades. One result.of cavitating flow, is the loss of pump exit pressure, it can be identified as NPSH3%.

[@johnkerr8019]

Good one "Hose Mourinho". I have completed a check of all my radiators, no sign of leakage and removed cover on the boiler, no apparent leaks and looking very dry. The pressure is dropping and radiators appear to be outputing more heat than is indicated on the digital reading on the boiler. Do you think it could be PRV or is something else going on. Thanks for posting this excellent and say hello to "Mr.G" Greetings from Glasgow

[@mozaman9005]

Hi I know this is quite old now, but if you happen to have drop in pressure which happens maybe over a month or so, with possible small leak, would you recommend the use of those leak sealer fluids? Can't seem to find the leak as described but havnt taken any floors up either on the ground floor, tiled and hardwood unfortunately!!

[@ErikOnEarth]

Thanks man, very helpful and informative! Found a small leakage in my bathroom radiator..

[@robertbridges5328]

Thanks, I was always told by the plumbers who came out to us that we had a water leak in the pipes in the ground, after this video I can see it the Pressure relief valve as from day one we have had water running out the back of the boiler. Will look at tank also thanks.

[@CoolMusicToMyEars]

Dont forget also tighten up the heat exchanger to it's back plate & rubber washers, this happens on a Viessmann 200W boiler

[@pkf4124]

My friend is a heating engineer and we have this issue so its nice to know the basic checks so I can let him know, before he comes round. Thanks for your advise.

[@nakedtraitor1802]

Excellent video. Thank you so much. My boiler keeps losing pressure and I'm having to top up everyday. Any idea what could be wrong?

[@bonkeydollocks1879]

Err the answer is in the video you just watched..

[@petersabatino3136]

Good man I'm a heating engineer of 30 years and you are a pleasure to listen too.

[@tinamendonca7241]

Do you live near the Middlesex area?

[@fieldsofomagh]

Great info on the central heating system.The plumber finished with his girlfriend this weekend, he said; "it's over Flo"

[@geoffcollins2094]

Awesome

[@gdfggggg]

Only 9/10 as it needed to be a bit shitter

[@derrickmartin4894]

Brilliant ,as a heating engineer i did not learn any thing from this video , but most of the plumbers I know would,

[@radukapu]

You are amazing! Wish there were more professionals like you in the business! Thank you for sharing your knowledge!

[@metube9541]

Great video, never thought about the pump being set too fast but that makes sense. Thanks.

[@williambarr4822]

When Bradley Cooper’s brother fixes your boiler

[@paulayton4317]

Lol

[@nimmichagger165]

Bradley Walsh

[@badrulalam7455]

Funny as hell

[@recall2880]

Who’s Bradley Cooper

[@dickymint9908]

@@nimmichagger165 deffo Bradley’s son 😅

[@garry843]

Thankyou for the video. I think you have jogged my memory, not having had to touch a boiler for years. The relief valve is dumping water at well below working pressure. I just moved into this property and the boiler although working extremely well has been tanding for over two years. Too much work at the moment, rather the leak than the cold at the moment. I'll order up a new dump valve ready for the moment. Have they done away with the filling key in the cover as i have a single ball valve in the line which in my experience is not the best idea.Thanks again.

[@linlegerton3482]

Thank you this was so helpful, living on my own after 23 years of marriage, starting to get the hang of things 😄

[@linlegerton3482]

👍👍👍👍👍

[@johnvonhorn2942]

Ask Plumberparts to pop round and give you a good servicing causing his pressure release valve to explode. That would get ten million views and you'd both walk away as millionaires.

[@bonkeydollocks1879]

I will pop round lin and fix it no probs

[@JJ-bv7fc]

@@johnvonhorn2942 loooool

[@AbdulJabbar-eh5ve]

You are a brilliant person, very nice any person with little experience of plumbing will love you mate have a nice day.

[@DeborahWalkerXOXO]

"Stumbled across" this video! One minute and some change in and I am wondering if I will finish it... very engaging host but at this point I'm questioning my entire life!

[@MrDaiseymay]

play the vid at 75% speed---much more absorbable.

[@jakecarson4587]

Very interesting video my uncle has lived in his property for 65 years the radiators are pre 1980s 1 Plummer said he needs a new combi boiler and new radiators the next Plummer said he can save money by fitting a new combi boiler and fit it to the old radiators now every day when switched of the pressure drops then needs topping up starts flashing low pressure but when it’s on its stable no problems now I am thinking should of got new radiators to

[@meridpeace]

Unlike your other excellent videos, this lecture seems to aim the already experts. This is a very fast lecture that flies over the head of 90% of the people who come to find a step-by-step procedures of fixing things in a very clear and brief presentation. Choose one or two kinds of popular boilers and show us doing it. People come to youtube to "see" not to hear. Otherwise, you are very knowledgeable and helpful. Please keep on helping.

[@plumberparts]

Hi Merid. Thanks for your comments and I hope you continue to keep watching! I would like to draw your attention to the pause button! All the best PP!

[@herrklamm1454]

Happiest plumber I’ve ever seen.

[@esjay8066]

Hi there been watching a few of your video's, wondering if you could guide me in the right direction? my boiler cut out due to the pressure dropping over a leaking radiator and we have had the heating on, the problem is.....I can't get water back into the system, turn on the filling and nothing is happening, no flow of water for some reason, I've bled the radiators, any help would be appreciated Thanks.

[@freespirit6209]

Brilliant. This will enable me to speak to my plumber much more intelligently! Thanks!

[@christracey2837]

Yes I stumbled across this. Excellent Vid Thank you

[@plumberparts]

No worries! Still making videos today, plus you can follow me on Instagram here: www.plumberparts.co.uk/social.php?social=Instagram FANKS!

[@LabRat6619]

The expansion vessel in the combi is usually way too small for the system! Secondly you can get a pressure breed across the flat plate heat exchanger on a combi. So many problems I'm always busy fixing lol.

[@thermion7869]

The main reason for removing the filling loop, is to prevent the contaminated water in the system getting back into the cold water mains supply.

[@danlux4954]

In Canada there’s a backflow prevention device on the fill.

[@Finglesham]

@@danlux4954 and in the UK

[@noorzahidkhan1691]

Hi thank you for sharing very informative tutorial, I ve got a problematic question , my 7years old Potterton promax 28 has releasing pressure, replace PRV which was blocked and replaced expansion vessel but still releasing very little water from PRV. Any suggestions or advise please? System is working fine apart from topping up to 1 and 1.5 par every 2 to 3 days :(

[@modclan]

Great Channel. I always come here for good honest advice. well done mate. keep the good work up.

[@richardwallinger1683]

Excellent I guess you are the man .. well done easy to follow presentation and nice clear voice. I had a slow, real slow, loss of pressure in the ch system with combi boiler .. there was some sign of discolouration in the wall and I sealed the outside patio believing it was leaking into the wall from the outside veranda. After watching your video and checking all of the connections I have decided there must be a very small leak inside the wall. so next step is the hammer and chisel ./. thank you so much for your input and support.

[@nickbrown3300]

Looking forward to testing the Expansion vessel and PRV tonight! Great video, love the way you explain the system, makes it so clear. Cheers

[@plumberparts]

No worries, thanks Nick!

[@jimgrimes818]

Good video, i'm sure many people have problems with pressure drop and this video will be of great help, however they should have their heating system checked before winter starts. Well worth it.

[@plumberparts]

Hasn't stopped there being 80odd dislikes!!! 😜

[@inkwhir]

The cavitation does not produce hydrogen, but just steam. During cavitation the water is simply boiling at room temperature because of the low pressure.

[@TW-mp8zx]

inkwhir correct and depending on the rate of cavitation it might sound like your heating system is circulating tiny marbles...

[@johnfoster5427]

Good to find somebody who sticks to the point and not waffling on about nothing, well done, good vidio

[@amirhussain1449]

lovely one pp,you've got good infomat've video's that's why you're getting the jealous plumbers disliking the vids

[@plumberparts]

+amir hussain Yeah, cheers Amir!

[@normanmcintosh4241]

Excellent explanation and I think you have give me the answer I required. New pressure vessel required. Thank you sir

[@djfriskyd1857]

Plumbers and Gas Engineers are two different areas of work

[@daveshirley]

Thank you soooo much! Thats saved us a bob or two! We had a filter installed as recommended but the guy hadn't tightened up one of the nuts quite enough and was trickling water out!! Tightened it up and Bob's yer uncle! Sorted!!

[@plumberparts]

Why has this got so many dislikes?! :)

[@thegrandmuftiofwakanda]

+plumberparts Not sure. This is good quality stuff.

[@plumberparts]

+billiepipersteeth Weird isn't it? I think most people just want to solve the symptom, rather than just dealing with the actual cause!

[@dieselbiggins]

+plumberparts it must be professional plumbers building a resentments against you for giving away trade secrets. 😉 I on the other hand salute you sir!

[@plumberparts]

+dieselbiggins Ha! thanks dude!

[@plumberparts]

+Robert Granger Cheers Robert!

[@Hogman666]

Great stuff we have a problem and it's looking like an expansion vessel and or pressure relief valve. Definitely feel more comfortable and confident on looking for quotes.

[@denismoloney27]

Isn't the braided hose is removed to prevent mains water contamination.

[@plumberparts]

+denis moloney Well kinda. Mains water can't 'contaminate' as such, but it can over-pressurise the boiler water if the mains valves start to let by. PP!

[@markrainford1219]

+plumberparts No, but the heating system water can contaminate the mains water if the check valve is faulty, that's why the bye laws say you have to remove the loop. I'm a plumber and Ithought this vid was pretty good, don't understand the dislikes either.

[@jaxmar88]

Yes, it is a water bylaw but ignored by many forign boiler manufacturers, Worcester Bosch mostly use a removable key (bridge) to comply with the regulations.

[@robertgreenaway5166]

It creates an “air gap”. So that if the check valve fails then heating water can’t contaminate the mains if there were to be any loss in pressure to the mains... doesn’t happen often but it does happen. If a water main was to burst for an example there would be a sudden loss of pressure on the incoming main.

[@lornaukbirmmie6076]

Great video, just a quick question. My boiler has lost ~ 0.35 bar in pressure over 6 months is this normal?

[@BrummieGuy]

I've searched Google for hours and can't find an answer, my boiler loses pressure over a couple of weeks, but ONLY when the heating is on. If the heating is turned off, the presuure doesn't drop. I presume this rules out the PRV and expansion vessel? TIA

[@markrainford1219]

It is almost certainly your boiler PRV or expansion vessel then.

[@BrummieGuy]

It's a Logic+ 30, it's now happening a couple of times a day. Isn't there a known fault with the logics and the error "Low flow lockout". All of the thermistors have been changed.

[@markrainford1219]

Cleethorpes Kid You really need to get it sorted sooner rather than later. Every time you top it up , you introduce fresh oxygen into the system and you will rot out your rads prematurely.

[@BrummieGuy]

Sorry, I misread the error message when I originally posted 3 weeks ago, It's not losing pressure therefore I'm not topping it up. It keeps switching off with the error message "Low water flow lockout". If I reset the boiler it starts working again.

[@Obsidianiron]

That sounds like a blockage, some boilers will have a software lockout if there is an excessive temperature rise across the heat exchanger, this is due to poor water flow rate. The software is trying to protect the heat exchanger and let you know you have a problem before you lose the heat exchanger all together, then it gets expensive. If you are not loosing water you might have to chemically clean the water side of the heat exchanger, but that's not really a DIY job, you need to know what you are doing.

[@anthonydyer3939]

My plumber fitted a spirotech deaerator. This will collect micro bubbles on the flow line and vent to atmosphere. So there will be a pressure drop, especially after the system has been flushed and refilled. Normal behaviour, and hopefully by removing dissolved oxygen, it should be less work for the magnetic filter and inhibitor. Other causes: colder weather = colder radiators which means a lower pressure. I typically see a 0.1bar drop for every 10degree drop in temperature. So with the autumn days advancing, I have seen pressure drop from 1.4bar down to 1.3 bar.

[@matthewlowy3039]

Sorry, there's no way cavitation makes hydrogen and oxygen... cavitation is making little bubbles of (just about) vacuum with a little bit of water vapour in that collapse almost immediately and can damage the impeller in the pump.

[@plumberparts]

Can you read what you post before you post it! I don't understand the sentence...

[@Biggles2498]

Matthew Lowy well done ! Cavitation also applies to Ship's Propellors (includes small boats) and causes damage to propellors under water ! I am an ex Ship's Officer.

[@plumberparts]

Good on you dear boy! My bro's in the RAF.

[@mrbachittarsingh9243]

It also affects the pcb

[@tauttechminusmanagedmusic3778]

Actually, it does. The cavitation is not just boiling of the water to create pockets of "air" (It's a combination of water vapour and dissolved air) - the bubbles are low pressure but they are most certainly NOT a vacuum. The physics of the situation dictates the water can break down into hydrogen and oxygen because in addition to the mechanical motion and heating there is also an electrical flow in progress. The multiple types of metal in the system ensure an electron flow. So yes, the pump is one of the places where water is split into hydrogen and oxygen. The popping you may hear in radiator is sometimes the two gasses recombining into water, but the amount of free oxygen is often less than the hydrogen because the oxygen binds to the corrosion inhibitors in the system or sometimes the chlorine in the water (molecular compound, not ionic). This leaves more free hydrogen to vent. Most of the gas coming out of the system when bleeding is just normal "air" that was dissolved in the water, but it has a higher concentration of hydrogen than the atmosphere. Cavitation damage to props and impellers is largely shock damage when the bubbles collapse. There are several videos on YT which explain how the bubbles are created using cavitation by snapping shrimp. Have you listened the din on hydrophones? - those shrimp a really loud! I'm no ship's officer (catering?), but I do my own plumbing, electrical work, electronics repair, and systems design for reactive systems such as fuel flow in aircraft engines . I also have degrees in Computational Engineering and Physics (lots of free time after breaking my back at the age of 24, many moons ago.) Plumbers get annoyed that I do all my own work, but I do respect their advice when I ask them to come and check my work; something I always do after finishing.

[@ayoolawore4566]

Thank you sooooo much. My heating is now working. I didn’t realise one of my radiator was leaking after trying to bleed it yesterday.

[@dwarfsbaneironfist2527]

Interesting, the gas fitter who services my boiler told me to leave the filling loop connected, previously I was removing it.

[@plumberparts]

Well most say don't just in case the fill valves start to let by.

[@tectorama]

If you have a flexible loop, it's best to leave it disconnected, but a lot of boilers nowadays, don't have a flexible loop. They have a permanent connection, where you have to open two valves to let the water in.

[@dwarfsbaneironfist2527]

Thx, I have a flexible loop, next time I pressure it I ill remove it.

[@daviddoyle2085]

During my courses there were a few reasons why you have to disconnect one is you could potentially contaminate mains water supply and the other was as mentioned if the valves let by and over pressurised the system. I've been on a visit where this has happens and it cracked the heat exchanger. Not cheap to replace.

[@daviddoyle2085]

plumberparts Quick question could you get an airlock in an unvented system the same way a gravity system gets theirs? We have an issue on one of my site where we have checked absolutely everything and even added another expansion vessel on the system and changed the AAV but the systems still losing pressure.

[@jeanhooson2933]

Thanks I’m 78 old lady and over the years have heard husband talking about different things with boilers etc and the pressure had started to drop an had kept topping water to just over one and it would suddenly go right up to 2 so put boiler off and whilst was having this trouble had noticed the little copper pipe had drip coming out as it’s by my gate so then found you and now think as all other things dry that what you say must be expansion vessel ,and or pressure relief valve or both . Fortunately or unfortunately I have home care with British Gas with being alone , more money to pay out that can’t afford but not much you can do about it I should av bin a plumber . The boiler is a Remeha Avanta plus 10 years old but not worked hard as have had to watch the bills but you say those parts usually die after 10 years so guess I know there’s nothing I can do but like to know what’s going on as our age gang had to do all our own repairs 40/50 years ago an the women had to get stuck in and help the fellas, but it’s a good video very informative thanks

[@b1h2u3p4]

Too much detail for head to take in.

[@highdownmartin]

b1h2u3p4 then you'll always need a plumber until you understand. I thought it was great and very understandable

[@lindaj5492]

3:25 Yep, finding a brown patch on a ceiling, or water dripping from a wall switch is BAD! Turned out to be a failed T-joint. Heating engineer who found eventually source of repeated pressure drops - on third visit - told me that the plastic “push-click” joints used with plastic central heating pipes “just do that” 😳 He had to go in through ceiling and replaced it with a brass one (‘luckily’ the smallish ceiling hole is in a walk-in cupboard, so not in my face whilst I wait for plasterer; insurance excess too high to cover cost).

[@kennethmunnoch1493]

In January had a system that was losing pressure fast. Frost had pushed out the insert from the drain valve.

[@ahsanafzal48]

My head expansion is about to happen 😨

[@danielpeters6129]

Very good useful video. Explains clearly exactly what to check and how. Will certainly try this and see if I can find the problem.

[@m.v.k4681]

Please talk a lot more SLOWLY so we can keep up and understand. Thank you. I have had to watch this about five times to be able to understand at this speed.

[@wardogass6101]

Think quicker. It was fine, in fact excellent , a welcome no nonsense delivery. The worse videos are where where you have to constantly keep fast forwarding because they are so slow at getting to the point. Like I said, think quicker :)

[@philipoxborough6110]

You can turn down the speed of the video in the settings at the bottom.

[@Dallo422]

Thanks so much for this info! We recently got our PR Valve replaced due to it being faulty. I'd like to quickly ask if I will need to put inhibitor into the system again? As every time the pressure dropped below half a bar we topped up the boiler with water from the filling loop. Does this mean we will need to put inhibitor back into the system?

[@larrycurrier290]

it's very difficult to compress water. no it's f****** impossible

[@plumberparts]

HAHA! you ain't wrong bro! Please consider subscribing - Uploading still today! *Please Follow my Vlog, TimesWithJames* kzbin.info *PLUMBERPARTS AMAZON TOOL SHOP* www.amazon.co.uk/shop/plumberparts

[@sergd7885]

I have baxi solo 2 pf the overheat lamp lights up and he does not want to turn on thanks for any help, pump ok work.

[@stuartsinclair6269]

Excellent video as always. Got a Worcester Greenstar 30si, That keeps losing pressure, got to top up every day, and put air in vessel. So far so good, run boiler after 10mins water leaks from prv outside pipe. And when boiler cools pressure is down again. Oh and water comes out of vessel. And when boiler is on, the pressure gauge goes way up to 2bar and over sometimes. Is it the prv or vessel at fault. Thanks for reading, feedback Welcome 👍

[@Tensquaremetreworkshop]

Best guide to a pressure vessel failure is the pressure fluctuates a lot when the pump start/stops. When working, it acts as a hydraulic capacitor, smoothing pressure changes.

[@michaellavery4899]

I like your video. It is the most comprehensive video regarding this problem I have seen. The only problem is you cover many topics whilst speaking really quickly, not giving the viewer time to comprehend the issues For example, you show the rusty nails and talk about hydrogen in the system. I don't think many viewers would have a good understanding of chemistry to understand that corrosion is the source of the hydrogen gas. I know viewers are put off by long videos, but they are also put off when they are overloaded with information they don't have time to understand. I know they can pause the videos but in reality they don't.

[@AbbasKhan-ud6mr]

Thank you for your videos, you've helped me so much over the years and saved me a lot of dough.

[@michaelloy4188]

Hi, many thanks for the video, very insightful. i do have a question. I do have a .oss in pressure and noticed that out side i have a drip leak. as per the video this leads me to think the Pressure release valve may be faulty. if this is the case, then would i also need to replace the vessel?

[@cyrustenable]

Hi James I have a worcestor bosch c440i and keeps loosing pressure and had a leak . The plumber which is WB accrediated one changed the expansion vessel and sealed a container with a tape under the boiler .The leak stopped but the pressure drop continued . He then added a bottle of Miracle seal inhibitor 250 ml ,the pressure drop was slower at a 0.5 bar a day but still is not right . There is no leaks from radiators or ceiling ,what could be problem please ? does it need more inhibitor as miracle seal bottle says it can be between 1 to 6 bottles . Many thanks for your helping in this dilemma

[@chrisseeker1]

A very clear and helpful video that helped me. I don't mind, but some people might find the delivery too fast - you are allowed to breathe. Other than that I do not know why you got dislikes. I thought it was well structured and explained.

[@plumberparts]

+chris vanderweele Hi mate, thanks for your comment, will consider it for forthcoming videos! PP!

[@raghidnaja3486]

Hi, I have a question, a main combi boiler had some pipe clicking noise so I changed the automatic air valve and noise is gone, but from that day, it started to show low pressure on the gauge. When topping it up, it just need a small swivel from the filling loop and it is all filled up?! Is it a pressure vessel problem?

[@dgibelli]

In my case I found the pressure was dropping because of two leaking thermostatic radiator valves. One was obvious but the other not. They leak where the pin enters the valve body and the heat was evaporating the water so there was no obvious leak. When I removed the thermostat I could see a tiny amount of water on the pin, fixed both these and the pressure has held for years.

[@mikeflynn4373]

Excellent as usual for Plumberparts.

[@mickthetinminer]

Hi James. V informative and useful info on your site generally but I can't find anything about my problem which is" pressure drops on my sealed system about 0.2 bar every couple of days. I've checked all the simple things like rad leaks etc and no leaks there. Property is bungalow with all pipework under solid floor so if there is a leak there well, I ain't gonna go looking for it. I want to add leak sealer next to see what diff if any it makes but is there a way I can add it without draining system and losing inhibitor I put in a few months ago?

[@pdtech4524]

Interesting video! I have noticed a very slight drop in pressure over a prolonged period, say 1.25 bar drops to 1 bar over approx 6 months, easily fixed with a squirt of pressure from the filling loop! This has been like this since I had a new boiler fitted approx 12 months ago, before that on my old system the pressure was fixed and never dropped (except one time when the shrader valve on my expansion vessel was faulty) So I've checked all the bleed valves on the rads for leaks as I know these were all opened during the new boiler install. No leaks found, had a quick look around, no damp patches or wet areas, but I wouldn't have thought it was any of the original.pipework as all was good prior to the install? I've also checked under the boiler for leaks, no drips, have checked the PRV outside but it's hard to tell if it's dry as we have very few dry days during winter but again can't see it being that as that was completely new during the install? Now I'm not overly concerned as the pressure loss is pretty minimal, it's just a niggle as I know there was no leaks before! If it gets any worse I'll contact the installer. Another thing he did mention was the pressure might drop a little due to the system 'settling down', I've done 2 top ups in just over 12 months, Is that acceptable, should I just accept it and not worry about it too much or have I got a very slow leak somewhere that could cause me future problems? 😁⚠️👍😎😯

[@loafersheffield]

I wouldn't worry too much. Once or twice a year is "acceptable". The norm, especially if you have a large system with lots of rads. I've got 3 "go to's" for this problem this very week. Just don't forget to get the boiler serviced annually to qualify for any manufacturers extended warrantee. Irks me no end when customers do not have an annual service and even more so when other you tuber, heating engineers fail to mention this when they do boiler reviews.

[@pdtech4524]

@@loafersheffield Cheers for the reassurance, it's just niggling me as I know I hardly ever had to top up the pressure before! It's not a huge system, 3 bedroom house, I have a double rad and single rad in the living room, all the other rads are singles, one in kitchen, one in hall, one in bathroom, one in each bedroom and a small rad in airing cupboard. So 9 rads in total, the boiler is a Worcester Bosch green star 30i, what sort of price would I be looking at to service that and what actually should get done? Thanks. It's just about due it's first service, I'll get the installer to do it.

[@loafersheffield]

It's a recurring annoyance to me that folk don't get an annual service. The Gas Safe guys with whom I closely collaborate with, charge around £80. That's "oop north" Sheffield rates. May vary according to whereabouts in the country you live. Seals on combustion chamber and addition of corrosion inhibitor may "bump" up the charge, if they are required. James isn't gas safe, so I presume he wont mind me posting this link. It's one of the best that I have found to date. kzbin.info/www/bejne/bJ2pZoKVl7ylobM The water cleanliness is essential and the system is dosed with adequate corrosion inhibitor. Gas safe tightness and let-by test mandatory. Combustion chamber is opened up, inspected and cleaned. Expansion vessel tested and recharged if required. Flue gas analysis at min and max tested, printed off and noted/stapled into your service/log book. Inspection of flue for obstructions or pinhole deterioration. Visual inspection of inside for any minor/ongoing slight leaks Clean condensate trap. Clean magnetic and particle filter..... My whinge: kzbin.info/www/bejne/l6a4YqSerd6Yh6s

[@dardobartoli]

Many thanks for these videos, really helps narrow down the problem. Tiny bit of dirty water came out the Schrader valve and not much air of a 15 year old combi system. Symptoms have been (for sometime): CH only works after running hot tap, constant filling of water (where does the water keep going?) to bring pressure up almost daily since xmas. Re pressurising expansion vessel via pump the weekend, it appears to be losing about 0.1 bar per day. A biasi M90F looks like I have to remove the boiler to replace the vessel. Damn! Thanks again. Bob

[@cerulyse]

Some just have rubber lining i think there is just one pipe going into the bottom so no air will escape this guy is a typical plumber trying to find unnecessary work to do you wouldn't put a magnetic filter on a boiler either

[@Biggles2498]

I have a MORCO 24 Series 2 in a caravan virtually new. Recently my Boiler Pressure kept dropping to 0.1 Bar whether on or off. ALL Radiator valves were checked ok by me and I had to repressurise about every 6 hours and I wondered where all the pressure was escaping ! I watched all of these plumberparts videos thinking it could be the Expansion Chamber at fault. Don't ask me how but the Warden on my caravan park drained the hot water system with loop open and heard gurgling ,shut the hot water then re opened it and an airlock was discovered which became cleared ! The Boiler has been behaving (touch wood) since !

[@MOB30A]

Absolutely fantastic and excellent video very valuable information. Thanks for uploading this video.

[@ellabbs]

awesome video mate, and well delivered, quite often i get to a boiler which needs repressurizing and they have no link pipe, how do you repressurize those types of boilers, a short vid would be great.

[@plumberparts]

Hmm, you'd have to use a hose pipe with valve at the boiler end and a mains tap at the other. Like old schoool back filling when you've got an airlock!

[@FC-wb5qk]

Your KZbin is brilliant but I'm a bit confused. Ok this might be a silly question ( I'm female if that's an excuse) if the heating is off and the Worcester DT20RF is doing hot water only does the pressure gauge still have to show pressure because mine is at 0 !! Does that mean something needs fixing or topping up or only when heating goes back on?

[@tellylgeorge]

Great video again. I've got this problem with pressure dropping almost daily. I have noticed that when the heating comes on it doesn't take long (quicker than usual) for the needle to go up and close to the red (over 2.5 bar) but drops quite quick when the heating goes off again. Would this point to a faulty expansion vessel?

[@solefreak2]

Having the same issue at the moment with mine. Topped up the pressure 3 times over 2days already.

[@tammyharrison1062]

@@solefreak2 WHAT WAS THE PROBLEM MINE IS DOING THAT

[@solefreak2]

@@tammyharrison1062 Can't remember the exact part, but one of pressure valve or something like that needed to be replaced. Luckily I had British Gas cover who carried out the repair.

[@dennisjones8447]

awesome, and I had a failed pressure relief valve exactly as he said. Went outside, found the vent pipe, and viola leaking. Big thanks!

[@plumberparts]

No worries Dennis! Glad to help you out mate. Get that PRV changed! SUBSCRIBE! ➡️👉 kzbin.info 👈⬅️ IF YOU HAVEN'T ALREADY! 😎

[@theoyanto]

Very informative and straight to the point 👍🏻

[@suzukigt7502]

Hi can i ask your advice please, if i replace the automatic air vent on the top of the expansion vessel, worcester 35cdi, do I need to drain down the boiler first, and also will i need to pump up the pressure to one and half bar with pump after replacement, the vent was replaced 4 years ago so is it worth doing as a service item.

[@jcmckean]

Extremely helpful video, thank you. Very clear and unambiguous as usual. Thank you