UNVENTED HOT WATER TANK COMBINATION VALVES - How they work - Plumbing Tips

All about unvented hot and cold water combination valves and pressure reducing valves.. We show you how they work, how to replace one that is faulty on your system and how to strip a combination valve down. We even have hand drawn diagrams all about how they reduce pressure, vent high pressure and have a balanced cold water feed out for showers and mixer taps.
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[@plumberparts]

*Links to the tools I use everyday here:* www.amazon.co.uk/shop/plumberparts Plus, follow my *Vlog “TimesWithJames”:* kzbin.info

[@n.rossiter6300]

Excellent fully explained video , really appreciated the 4-stage demonstration (the valve in use in the house, the removal and refitting of the valve, the dissection and explanation of the valve components, and then the diagram to show the theory of its working) I have never seen anyone think to go through all stages before. Absolutely brilliant teaching! Thanks!

[@benmcdonnell4167]

Absolutely brilliant! Just moved in to a refurbished house with our first pressurised heating system to cope with and this was essential, thank you.

[@beadowarrior]

Have to say, great explanation. If you ever get tired of real work, you've got a skill at teaching thats really good. Keep it up.

[@plumberparts]

+Philip Burkett Thanks Phil!

[@plumbtblue]

As much as i like the photo disasters and cat updates, i'm glad to see you're still doing the informative, helpful, serious stuff. Well done James

[@plumberparts]

+Phil George Thanks for your comments Phil, I'm glad you like our videos!

[@SMGMultitrade]

Love these videos, you have helped me so much as a new plumber

[@rafmo7413]

What a brilliant video, it's taught me where the water goes in to the valve and which ball valve I need to turn off to isolate the tank. Amazing explanation

[@barenakedwoodco]

Amazing video. What a shame the 4 useless plumbers didn't spot this on my unvented system with a balanced cold feed coming out. Such a simple explanation as to why I had no water flow from any hot and cold taps but superb pressure before the combination valve. Some never even went near the airing cupboard to look. Some said I just needed all my pipework replacing or it was the water boards fault. The 5th plumber nailed it within an hour. This is in my tenanted property and I had to rehouse the tenants as the water virtually stopped running. No shower, no toilets, nothing...it was this one little but very important valve. £1k later and I feel I now know my entire heating and water system inside out! I'm definitely subscribing to your feed. Thank you!

[@SkillBuilder]

The explanation was a work of genius. You didn't say 'equilibrium' once.

[@plumberparts]

+Skill Builder Ha! Cheers guys!

[@ranjitpatel496]

You are amazing giving your time on explaining different plumbing & heating issues.My trade being plumbing heating I'm learning all the time. Also I don't understand people giving thumbs down anyway thank you 👍

[@roopy1]

Mine has failed and I have a plumber booked in to fit a new one, but I just wanted to see what it did and how it works. This was perfect 👌

[@blendi3825]

Great video mate! You're the best teacher I ever seen.

[@peteblaney5744]

Excellent explanation, now I know how a combination valve works!

[@pederoba100]

Very well explained. Cheers mate.I am from Brazil and I find your videos very helpful for a new plumber starter

[@plumberparts]

+Alexandro Casagrande No worries Alexandro!

[@SyncMan172]

Love this video. Our house is 17yrs old and we have an oso unvented system. The hot water pressure has been decreasing quite a lot over the last 12 months to a point where if anyone flushes a toilet for example while someone is in the shower, then the shower stops. The water board say no issues with mains pressure to the house. We have a PRV on the mains and one at the tank. Hoping getting both these replaced will fix our issue.

[@jon8583]

I have a very similar problem, with reducing hot water pressure over time. Did you work out the problem? I am thinking it might be this value.

[@shoutforit]

beautifully explained. this gent is a brilliant plumber.

[@Micktheadventurer]

Thank you for all your videos. I love the knowledge you have. It's a shame you have to sell out sometimes but I get why you do it. I wish I had your ideas.

[@ragingbearbull]

Thank you for the vid. I am going for my G3 course in a few weeks time and this was very useful.

[@ir7868]

Brilliant Can you make video how to check pressure on combination valve. Thanks

[@pkumar5411]

great video and detailed information on the under the bonnet of the valve system.

[@radishpea6615]

2:30, that you for the explanation of the balanced valve. Who did the plumbing, it looks as if it does or did leak. Could a run of, for example hot in 22mm pipe and cold in 15mm pipe mess things up?

[@TheWesleymoreira]

Buddy I have an electric unvented cylinder from heatra sadia premier plus. It’s only 2 yeas old and It has 2 elements. looks very knit but I can’t find a video on how to pressurize it. I normally find everything in your channel but I couldn’t find this time. Thank you. You channel is great!

[@handyguyhints1992]

Nice one PP! Not the kind of thing I get into but I like to know how things work all the same!

[@plumberparts]

Cheers Handyguy!

[@mattgriggs6564]

James loving the videos mate ! I'm planning to be an apprentice plumber so this has been an amazing help ! Also where's the tshirts ?!?!?! Get yourself some Plumberparts merch !

[@plumberparts]

Ha! Will try to mate. PP!

[@christopherleveridge7582]

Really good video, very informative! Thank you for the information 👍🏻

[@UberAlphaSirus]

Nice, I'm gonna love this series.

[@plumberparts]

+Sirus Thanks Sirus!

[@scottbarker1407]

Not a plumber but I love this channel, could I ask why you put or could put an expansion vessel on the cold water pipe?

[@jamesthompson6731]

Brilliant video. Love all your stuff. Apologies if this question has been answered before but can the valve restrict flow rate?

[@riproaringblues]

Really helpful tutorial, thanks!

[@mikeevans1390]

Great really helpful thanks.

[@peterk75a]

Any chance of seeing how to clean the filter. I have a Reliance version of one of these and I suspect its partially blocked as the water flow has decreased. I love this channel.

[@descantrell5319]

Excellent video, much appreciated.

[@jwsplumbing124]

Best plumber out there 👍

[@bobbylawrence81]

Nice to see something a little bit different J.

[@plumberparts]

+ROBERT LAWRENCE Cheers Rob

[@ob1983]

Fantastic vid, really helpful. Thanx 👍

[@chrismp8477]

Got a quick question.... does the feed for the cylinder HAVE to be on the opposite side of the mains in or can it feed from the side outlet which would normally feed the taps to the property??

[@TheTEAR1]

Explained so nicely

[@malcolmbaker8180]

My parents have a modern ish house 90's. They have a condensing boiler in the garage, 12 radiators on the system some have thermostat valves. In the airing cupboard they have two actuators and a pressure release valve. The system is made up of microbore pipes and the bigger pipes. The system has never been great in the sense that extra radiators have been added before we got the house some parts get more heat than others. The main problem is the pipes bang sometimes, I assume this is air in the system? Can you tell me how this would happen and is it possible to fix? Thanks in advance. love the informative videos.

[@alexanderthompson2704]

What would happen if the expansion vessel was piped up on the balanced cold side?

[@lord3296]

just a quick question. do you need to drain the cylinder before carrying out this work?

[@surreyelectrical6192]

How to empty a magaflo hot water so it can be replaced Thanks John

[@PP-pf5ex]

Hi, fantastic videos! I’ve just had a unvented cylinder replaced, a new combination valve (made by reliance water controls) has been fitted, but I now find a lot of noise (water flowing noise) when any hot water tap is turned on. I can only best describe it like an old fashion toilet cistern filling up. It’s so loud that you hear it in adjacent bedrooms whenever any hot water tap in the house is turned on. This didn’t happen on a previous separate 2 valve set up, is this considered normal, or do I possibly have a faulty combination valve?

[@Wayne-Jones]

Can I use this system on an indirect cylinder if I convert it? bear in mind I have a coal boiler, no t sure ir the pressure relief system would be adequate enough.

[@john-of-the-north]

This was a really good video - many thanks

[@plumberparts]

No worries John! Thanks for the comment dude!

[@1809Cookie1]

Excellent explanation

[@plumberparts]

Thank Cookie!

[@rob5896]

How come they didn't use the regulated cold supply, there surely must be mixer taps in the house?

[@DeeBythesea]

Hi there is a tap with a tag "mains water" next to the water tank. I noticed it's leaking and tightened it. Still leaking. How do I stop the dripping?

[@shaonmukherjee1389]

great video. could you do a video on topping up pressure on a halstead boiler please

[@plumberparts]

Ha! will try.

[@robinacjohnston]

Watched this video last week before swapping out my identical combination valve. Although the replacement looks physically different, I found it to have exactly the same footprint and did not need to alter any pipework to install it. Great to see what was involved before I did it anyway. Many thanks.... One question for you on unventilated systems, I find that my megaflo tank looses its air bubble in about 6 months. Is that normal or indicative of a problem?

[@Mamoo480]

Very interesting and informative

[@martynairey2318]

Brilliant video thanks. Quick question. My valve is dumping water. Is it worth giving the cartrdge a service or do I have to replace the complete valve. Its an RCW presure reducing valve (multibloc MK2) On a Megaflow white cylinder. Thanks

[@ClaudioLorente]

Hi why the pressure gauge on my megaflow goes up to 5 bar when hot water is pn? Does the comb valve has a built in non return valve? Thanks Claudio

[@MrCamohoj]

Do they require a annual service and is it a case of stripping the valve , cleaning and replacing sealsl and filters and resetting?

[@kimbrey1]

Absolutely fantastic! I'm doing my degree and you are my main reference

[@kimbrey1]

You are amazing 😁

[@plumberparts]

Cheers Kells!

[@Nikiforos59]

Fantastic video the best teacher ,,

[@sandspatel]

Hi do you need to empty the tank fully beforehand?

[@peters3125]

Great video really explains it well. Love to know why a combination valve fails. I’ve got a caleffi 3/6 bar installed 2 years ago. Expansion tank has a pin prick hole. So I’m told membrane needs replacing. Now on reflection they’ve told me the combination valve also needs replacing. Really surprised both needed so soon after installing (whole system 2 years ago) . Any thoughts

[@razhusain2298]

Hi mate I wonder if you can help? My cust has an open vent system, boiler is potterton profile. They just want maga flow fitted, instead of the tank . They don't want to go to sealed system on the heating side.

[@drsquirrel00]

Isn't the point of the thermostatic valves on showers to deal with differences in pressure/flow between the incoming hot/cold ?

[@jimm3441]

Looking some advice James, I have a pressurised system at home , is it ok For it to go above 3bar pressure when the heating is on and if so what pressure Will it go to before the water is diverted out side , many thanks.

[@jezzajgs]

Just discovered this part of the system when it started dripping - is this how gas regulators work as well?

[@indrin12]

Thank you for sharing

[@forreal8704]

Love this video. can you do more of these explenation videos ?

[@plumberparts]

+Jake Miller Will do!

[@ikra]

are we legally allowed to DIY change this ourselves? Do I just turn off the mains water tap and I can start working on it?

[@kena2051]

My expansion vessel is coming away from the wall. If I turn the cold off at the mains and drain the vessel, can I getaway without having to re pressure the bladder?

[@ownyourworld]

Thankyou for this video

[@Lareon]

If i wanted to change just the cartridge with an unvented cylinder, do i need to just turn the water off or drain the system entirely?

[@shifty277]

F*cking brilliant video, thanks for all the effort you put in to your videos and channel all whilst carrying out your day job, much appreciated.

[@plumberparts]

No worries dude!

[@stevenolivero5207]

Really helpfull thanks

[@knight1605]

Great video. Can I assume then that if this valve leaks it's from the bellows? If so....is this repairable? Hold tight!!!

[@natbug3891]

Hi how do i increase the water pressure in my house because someone came over to fix my heating and after he was finished the water pressure seems to be low pressure? any ideas would be appreciated thank you very much

[@hannes5203]

Excellent, thank you!

[@danmilz1977]

Hi how would you attach a cold water accumulator to a system like this? Thanks

[@eamonnhaughey9468]

Hey James, Is this the same way pressure reducing valves work? Love the Vids.. Cheers!

[@plumberparts]

+Eamonn Haughey Yes mate!

[@oliverdaley934]

Thank you

[@mmon764]

Your videos are quality

[@B1cam]

Thanks. Very interesting.

[@plumberparts]

+B1cam Cheers!

[@barrleggett5228]

Could a faulty valve 'stop' the flow to the boiler loop pipe? As my water pressure is now low and the mains feed to the boiler, i.e. flexible loop pipe is zero. I've opened both the valves either end of the loop pipe and no water flows?

[@MrDingle1987]

@plumberparts I had my combination valve replaced not so long ago, before the pressure through my shower and taps was at a constant flow, now since it was replaced the pressure drops dramatically after 20 or so seconds. The water comes out at full bore but that could be due to the expansion vessel giving it a boost but after that pressure drops. Could i have a dodgy valve?

[@davidmetcalfe3593]

Could you let me know how I stop mine going over 2.1 over night please it keeps leaking off outside

[@wight69star]

Thanks for the video, do I have to drain the system to fit the valve or is it enough to just to stop the water coming in from the tap just above it.

[@masterchaz100]

I would shut of cold mains to cylinder then open up hot taps whilst draining down with a hose on a drain off closest to a door also may aswell turn boiler off if it's on as you would be heating nothing

[@okitwas5seconds]

Brilliant, thanks :)

[@Harmonical1]

Brilliant informative video.

[@plumberparts]

Cheers!

[@setarcostopal]

A question please! On my telford 150 direct unvented it says that the precharge for the expansion tank should be 0.2 bar less than incoming. Does that mean 2.8 because the exp. Tank is fitted after the 3 bar combi valve....or does it mean 6.8 which is relative to the normal system pressure of 7 bars before it enters the combi valve.....confused i am!! Cheers

[@jamesg4266]

Very interesting mate James, do these fail very often?

[@plumberparts]

+James Garlick Hmm, only once in a while.

[@alexlancaster7681]

Love your videos mate, I'm about to start an apprenticeship at the age of 26, so been watching and learning what I can to have a bit of a heads up going in to the course. Just out of curiosity do you do gas? Hold tight 😝

[@plumberparts]

+Alex Lancaster I used to do commercial, LPG and domestic, but keeping all the tickets with an Oil cert and an AirConditioning ticket just cost way to much so I let them slip! Sleep a lot better now!

[@alexlancaster7681]

+plumberparts brilliant thank you and I can imagine it could give you massive headaches.thanks again and hold tight

[@ReadandWite]

Love the Olin Skis !!! Mark V ??? If you ever want to get rid then let me know. The Dynastar you can keep.

[@plumberparts]

+ReadandWite Ha!

[@ReadandWite]

I have a pair of Volant (USA) carvers 190 (all steel) for sale or exchange.

[@Carlostype]

hi pp, I've got a thermal store that I'm going to drain down the system tomorrow then isolate feed and expansion, I intend connecting a mains hose to our tfi filter and open valves in accordance to direction of flush then open heating side of diverter valve with drain hose on lower rad to then I hope go round rads to flush, have I got to fill the store first b4 I flush, I'm thinking it'll give me more time incase it fills as I flush. Sse wanted to power flush my system for £600 and I got it going by flushing from tfi through flow pipe to boiler drain( poor flow) and I now want to get the ds40 out so to inhibit, I've a priority system with only 1 pump, thanks mate

[@timbrown2573]

Hey James, what's the loo roll doing next to your monitor, anything to do with your screams to 'hold tight'? Just kidding mate. I love your videos. Top stuff.

[@plumberparts]

You know what it is Tim! Hay fever!!!! All year round!

[@alarge1819]

Grant. What is the difference between an expansion vessel and an accumulator? ps: great videos by the way.

[@plumberparts]

Expansion vessels account for system water expansion. Accumulators gather a great deal of water keeping it pressurised ready for use. Have them on low pressure/poor flow systems. Will be doing a vid soon! SUBSCRIBE! ➡️👉 kzbin.info 👈⬅️ IF YOU HAVEN'T ALREADY! 😎

[@redglazedeyez6652]

just moving into a new house. our current house has a combi boiler so its all nice and easy and what i been used to for 20 years. new house has a big tank in bathroom cupboard like this video with pipes all over the place. radiators are cold downstairs but hot upstairs. ive been watching alot of these vids and getting an idea what to do. (called a plumber who suggested new radiators and power flush system. he hasnt even bothered balancing it so eff him il do this.myself first). but i keep seeing a red knob (on mine its red) with a numers on it. its situated not far from the pump. i cant seem to find what it is. its got a screw in middle of it...and it turns if.i take.screw out i guess..its set halfway between 1 and 2. no idea what its for.

[@dunboy7874]

It's the auto by bass, should be set at 3bar. I wouldn't touch it. Have you got a room stat upstairs and down stairs? If you have you may have a faulty valve which let's hot water to the down stairs rads. If the rads are just getting warm then maybe just need a flush out. Hope this helps.

[@Isaac-iv3sj]

Loved it...

[@plumberparts]

THANKS MATE! If you get a sec follow me on Instagram! www.Plumberparts.co.uk/social.php?social=Instagram

[@runrunjump7400]

Why cant you just replace the pressure regulator top spring and leave everything else in place?

[@J0n35y172]

My Megaflo sometimes makes a banging/popping type noise from inside when heating up the hot water any ideas? Works fine and there's no water in the tundish. Cheers James. Hold tight!

[@plumberparts]

+J0n35y172 Could be a really scaled up one, or boiler temp really high!

[@Milan-sy5wh]

Hi I got the exact same problem did you manage to fix it if so please tell me what you did

[@Milan-sy5wh]

Hi I got the exact same problem please tell me if you managed to fix it if so please tell me how you did it because it's making a very loud banging noise and it's disturbing us

[@tonyb5469]

Can air trapped in the tank effect the working of the Valve? I.e. Will it still open if there is air in the tank?

[@UberAlphaSirus]

Tony B nah, it will just pressurise the air to 3 bar aswell

[@tonyb5469]

Sirus thank you

[@simonc4810]

3 Bar??? We have a 30 year old Viessmann verticell that’s rated at 10 Bar! Mains inlet to house has a BWT backwash filter with gauge and pressure reducer built in which is set at 4 bar. The manifold above the tank has a pressure vessel, gauge and safety valve rated at 6 bar. Needing a 3 bar reducer to protect a tank would leave me questioning why I bought something so fragile when clearly more robust alternatives have been around for decades.

[@nathangroves3177]

Valves and not valve. Where's the one from the thumbnail?

[@bribrolly4]

I’ve been looking through your videos trying to get my head around the heating system in our new house, and they’ve been excellent. Our santon premier plus PP210B tank is fed from a gas boiler. When the heating is on or the nest thermostat is calling for hot water no noise comes from the tank. But as soon as the heating turns off, the tank (and throughout the house) you can hear what sounds like water running/immersion heater through pipes. I’m concerned that something might be wrong and at the very least it’s keeping us up at night as the noise can be heard. I think I’ll have to resort to getting someone out to look as it’s stumping me. But i thought I’d ask before I do. Thank you in advance

[@vdotme]

top stuff

[@plumberparts]

Why has this video got so many dislikes? Weird!

[@marilynperks6111]

May be because of the G3 regs.