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BYPASS VALVES ON S PLAN AND Y PLAN HEATING SYSTEMS – Short Cycling prevention – Plumbing Tips

BYPASS VALVES ON S PLAN AND Y PLAN HEATING SYSTEMS – Short Cycling prevention – Plumbing Tips


– Hold tight. If you’ve come across this video trying to find out a bit more information about the bypass valves
in your heating system, then great, we’re gonna cover
them in seconds from now. Before we do, I’d please
like to ask you to subscribe. We do loads of videos
every week, and all that. We do lots of photos and videos and stuff on our Facebook channel as well. There’ll be a link to that
coming up in the video. Anyway, I hope you enjoy the video today, and remember everyone, to hold tight. Plumberparts.co.uk. Honest reviews and advice. Hold tight and welcome to today’s Plumberparts.co.uk video. My name’s James and this is gonna be a really, really quick video. What we’re gonna talk about today is bypass valves. Now on this particular system here, we’ve got a bypass valve that’s effectively a gate valve. So that means that you
set it at one point, and then leave it for
the rest of it’s life. But you can also get
automatic bypass valves that are a lot better because they’re a lot more efficient
for the heating system, but for the purposes of this video, to see where they fit
in on a heating system, this particular layout that we’ve got behind us here is just fine. So if you come over here and have a closer look, I’ll give you an idea about what bypass valves do, where they sit in the heating system, and then we’ll go back to the white board to show you this lot all
laid out schematically. So all right, on this system here, we’ve got our flow coming
up from the boiler here. It goes through the pump, and the up. We’ve got an automatic air vent up there so that just vents the pump out. And it comes back down here, and this is a S-plan system. At this point here, it’s really important. Effectively it can go one of three ways. If the radiators are calling for heat so the programme is calling for, and also the thermostat’s calling. This two port valve here is going to open up, send a live supply to the boiler, and the pump to come on. That’s great, brilliant,
everything’s good. We’ve got loads of water
coming around there. If this tank here is calling for heat, so the programme is calling for heat, and the thermostat in the centre of the tank is calling for heat, this two port valve
here’s going to open up and send water around the
coil of this tank here. Well funnily enough actually, this tank doesn’t actually
have a call on it. It’s tank in tank beast, but let’s say this tank
is not calling for heat, but this radiator valve here, the two port valve for
the radiators is open. That’s where the bypass valve comes in. So say you’ve got say ten radiators on the heating system, and they’ve all got thermostatic
radiator valves on them. As those thermostatic radiator valves turn down and turn down, on an old system, and also on some of the
new systems as well, that’s gonna cause more
stress on the pump. Now that’s where the
bypass valve comes in. The bypass valve, especially in the type that we’ve got here, is set to constantly let a small trickle of water through directly onto the turn back to the boiler. What that means is is that you’ve got a constant flow around the heating system at all times regardless of whether the radiators are open or either of the
two port valves are open. This is also really handy if either of these valves fail. So to recap really quickly, the bypass valves ensures that there’s a constant flow of hot water around the heating system through the boiler and the pump at all times regardless of whether there’s been a problem with any of the valves or if the TRVs are open or closed. So why do we want to do that? That’s the big question. If either of these valves go wrong or there’s some sort of problem and flow is completely restricted round the heating system, number one, the pump is
gonna struggle, okay? Now in new modern pumps like this Waller that we’ve got behind us, they actually know what pressures coming off ’em and they can actually turn themselves down automatically which saves you energy. But even with that function there it’s never going to
fully switch itself off. And likewise with an older pump as well that doesn’t have this
automatic function on it, they’re just gonna keep bashing away at the certain speed that
they were running at. So that results in a problem with air. You can have cavitation and air problems. I mean on this system here, if this piece wasn’t here, and there way air going around, eventually that air’s gonna come out of that automatic
air vent up there. The system pressure’s gonna drop down, and then the pressure switch on the boiler’s gonna go and
the heating’s gonna go off. So that’s how important a bypass valve is. Without that bypass valve, that is the series of
things that can happen that can make a heating system go wrong. Likewise, say the pump
is just bashing away. A little bit’s just getting round somehow or other through one radiator. You’re gonna have a boiler that’s bashing away, still got a
live supply going to it. As to the pump as well,
and that could over heat. It could also cause steam. So that’s why it’s really important to have a bypass valve, and to reiterate it, let’s say you’ve got a full flow of hot water through the boiler and the pump at all times regardless of what any of the controls of the heating system are doing. Another point I’d like to make as well is that last week I went and looked at a job, and I saw that they did have a bypass valve on it,
but it was on the other side of the two port valve
going to the hot water coil which made the bypass completely pointless because when that two port valve is shut, there wasn’t any bypass. It was effectively being valved off. So it’s very important
that the bypass valve is fitted before any controls
on the heating system and goes directly back onto the return to the boiler. So how do you set an
automatic bypass valve up? Well usually what I do is, especially in a gate version like the one we’ve got here, I will basically crack it open about three or four turns, and to say you can hear a
nice little hiss through it. Also a great way to test that the bypass valve is working is to make sure that the system is completely cold, and then turn on just the
heating system radiators. And what you should be able to do then is just turn on this bypass valve here, feel the return pipe, and feel that that’s getting warm as well. And then you know that
it’s getting round here without being heated up straight away by the coil and the hot
water tank just here. One thing that’s worth mentioning as well is that bypass valves are really important when it comes to balancing out a heating system. And there’s obviously, you’ve got the main flow coming up here, and if this is far too open, then it’s gonna shove
loads of flow down here and back to the boiler, and that means effectively that if the radiators are calling, they might not be getting the required flow and heat from the
boiler that they need. So therefore you’ve gotta think about how you’re gonna set this little valve up. The great thing about
automatic bypass valves is is that you don’t have
to worry about that. Set that to the certain number that you’ve been told
to by the manufacturer ’cause they’re all different, and that’s gonna open and close automatically because the pressures that are on the back of the valve. They’ll open up, completely on their own. The great thing about
the Waller’s UNOSP coat is it has a little display on it as well. Setting’s it’s kinda what the outlet pressure is on the pump which is really really handy when it comes to kind of demonstrating what a bypass valve does. So at the moment, the
systems set up for hot water which is really good for the little demo we’re gonna do now. The two port valve if the radiator’s is completely shut, and the two port valve for the hot water system
is completely open. And also at the moment, our bypass valve is completely open. So at the moment the pump knows that the bypass is fully open, and that this is open up here, and it’s really trying to wang quite a lot of water through
at quite a high rate. So now we’re gonna
strangle down the bypass which you see that the number on here which really equates to how much power the pump is putting out should start to drop because it’s being required a lot less. So let’s just wind that down. We’re at 22 at the moment. Getting smaller and smaller, 20. 17, 14. That’s completely shut now, 12. This pump is completely slowed down now. It’s recognised that there’s not enough need for it to have a load of water flying through it. And that’s great for this
demonstrational video, but obviously if you’ve
got a standard pump, that’s just gonna carry
on going at the same rate. I’ve strangled this off here as well so we can get a good idea of what the flows are gonna be like. So now I’m just gonna
slightly open this up. And then I’m gonna go
so it reads about 12. There we go. So it’s reading 12. It’s just slightly open. That means that our bypass is just slightly open and that’s just letting water trickle through regardless of what this two
port valve is doing here, and regardless of what any of the valves are doing here. So then, we’ve got our boiler here. We’ve got our flow coming out of it. We’ve got our pump. We’ve got our two port valves here. One going to the coil and our cylinder, and then back to the boiler again, and then one going to the
radiators in the house. Like so. A nice little single pipe
system we’ve got there. Very nice indeed. So the bypass has to go
back onto the return, and usually the easiest
way for you to do that is because this part here is usually all in the air and cupboard together. So if we just dot this round here, we think that that is all in the air and cover this bit. So what we’re gonna do,
we T into this piece here. We put our bypass valve on there. And then out that. So we’ve got water coming out here, out here, up here. So if this shuts or this shuts, water can carry on going up the bypass back round there, and then you’ve just got a constant circuit of water like that regardless of what these two valves do or what any of the thermostatic radiator
valves do on the system. So there you go. I hope you’ve enjoyed today’s
plumberparts.co.uk video. I hope this has given you a better idea about how bypass valves work and what their position
is on the heating system. We were asked to do this video by one of you, our viewers, so thanks ever so much for that question. If you’ve got any questions or you need anymore help or anymore information, then ask us in the comment section below or contact us through
our Twitter and Facebook. Anyway, I hope you enjoyed today’s video and I’ll see you in our
next plumbing video. Remember everyone to hold tight. Plumberparts.co.uk:
Honest reviews and advice.

41 comments on “BYPASS VALVES ON S PLAN AND Y PLAN HEATING SYSTEMS – Short Cycling prevention – Plumbing Tips

  1. thx mate this is really helpful , iam from Tunisia and i almost watched all your video that you made , so next year ill move there to England to be wiv my lovely wife so i can continue work plumbing at least knowing the basics of the plumbing systems there 🙂

  2. Hi I've just had a new baxi boiler fited replacing my powermax boiler I keeled the old radiators because my house is only 12 year old I had pressure drop problems with old boiler now with new. boiler to so come to the conclusion I've a leak but all pipes are in wall micro piping how can I test for leaking I've no damp patches any where hope u can help hold tight,

  3. I have a mains water pressure uñvented Ho water cylinder with an internal integral exspansion.vessel. How do I rècharge the exspansion vessel please.I know with an external vessel you can use a pump. Any advice wold be appreciated, peter hofman

  4. Nice one James. I was asked a while back why this circuit was in place and now I know! Very educational. And good to see Big G in on the action. 😂 👍

  5. Hi mate your videos are awesome. I learned so much so thank you for that.

    I was wondering if you can help me out a little though ( I don't ask for much do I!) I've got a small bathroom. It's got the set out like this Wall, 15-20cm space, toilet, sink looking at it left to right. Can I get one of those Japanese Bidet toilet seats in (it needs power) or its it too close to the sink. The seats are available in 240v.

    Thanks again!

  6. Thank you for replying.The central heating has a separate feed an exspansion .The hot water cylinder is a Tornado I don't know if it is called a mega flow. All I do know is that it has an internal,integral exspansion. Operating pressure is 1.8bar with mains water pressure of 12 bar.It has a tundish to outside which I believe is set operate at 100 degrees

  7. Thanks James, great video…I have one pump, one three port valve and, I'm pretty sure, No bypass….I it might be built into the boiler but as that's a 15 yo Potterton, I doubt it. When the heating goes off for the summer, I switch the pump right down, also I don't have TRV's on every rad so I think that has the same effect, right? 🙂

  8. would changing from a feed and expansion tank to a sealed central system make the water flow better. ive a kitchen rad that wont heat and ive been advised this may solve it. ive tried EVERYTHING 😂

  9. Hi mate. whats your opinion on these new pumps on old systems with not the best flow, as they slow down when they feel resistance , (its not always the best idea to start power flushing old system until the customer is ready to fully upgrade boilers rads etc) would they not require a pump that has some humph to compensate ?

  10. Hola hermano – does the by-pass also serve to ensure that some of the immediately heated water is fed back to the boiler so it is not receiving very cold water from the first fire up after standing idle for a while, so as to reduce condensation on the heat exchanger? Or was that just for old systems? Muchas gracias y saludos.

  11. Do I need a bypass valve on a combi system? I have a couple of 2-port zone valves for my rads and sometimes they bang when the heating comes on. I think I may need a bypass circuit installed before the zone valves.

  12. pretty sure i got a bypass on the return from the cylinder coil. In other words its been placed after the pump and 3 port valve and cylinder on the return to the boiler. no wonder that pump makes horrible noises!!!! cheers plumbing parts.

  13. hi i have question

    My thermostats giving Alert

    (No Power Heat/cool System)

    what dose this mean

    and there something i can do….

  14. I wouldn't ever touch an unvented cylinder, they can blow your house apart, worst than a deadly gas leak that ignites

  15. Hey, Quick question, i have a vaillant system boiler which has a built in auto bypass, but i saw a comment on a forum that you need to add a separate one if you have a S plan. Is this true? Thanks!

  16. I've got a bypass on an open vented system with a three port, mid-position valve. Not sure what the purpose of the bypass is here though – doesn't the water always have somewhere to go with a mid-position valve? Is the bypass only in case the mid-position valve becomes entirely blocked somehow? Cheers for the many excellent videos.

  17. I have a combi boiler with 2 zone valves, 1 does the house rads and the other does my garage conversion rads. When the thermostat in the house is up to temperature but the garage requires heat, the correct zone valve does its job but my boiler then starts to make a high pitch squeal like the pressure has increased too much on the other zone. Would a bypass valve solve this?

  18. Links to the tools I use everyday here: https://www.amazon.co.uk/shop/plumberparts

    Plus, follow my Vlog “TimesWithJames”: http://www.youtube.com/c/timeswithjames

  19. Help…advice. Y plan system..30 odd rads, gravity fed cold feed and expansion were within 100mm each other South side of pump. Anyway..Did a Power flush, fit 25 new trvs. Cold feed back filling…vent fine but heating going up intermittently up the cold feed and F/E cistern over flowing. Been back tonns..Any Way we changed the cylinder for new stainless steel cylinder and converted to S plan. By pass auto..A auto air vent and even a Spiro air elimintor. Going back tomoz to fin wiring but I'm bout lost as to why it did it today? Oh I repiped a tower air separator in before the pump and cold feed within 50mm of it. I have mentioned converting to sealed but customer not fancying it due to pressure..Help?!

  20. Hi can you offer any advice on a problem I have with my heating/ hot water Kingsplan Tribune HE system. The hot water is too hot, I’ve checked the cylinder stat by removing it and testing the bulbs in hot and cold water and I’ve also checked the zone valve servo motor is operating. So I set the stat to 25 degC but the water is way above the set point. Any ideas?

  21. Great vid! I was wondering if you still do jobs around the Cambridge area. I would really like to use your services please.

  22. Hi great video, newbie to posting please bear with :)…. i have a Ideal Vogue 26s (pwm modulated pump) Condensing Boiler in the loft with an S plan heating system , there is NO bypass valve fitted, could you advise on where exactly does the auto bypass valve need to be fitted ?…the Flow and Return 22mm pipes come down in parallel down through the ceiling in the airing cupboard (5mm apart very neat but a tight fit)….there is a Ideal filter fitted about 300mm below the ceiling , so thats a bit tight to fit it…then they drop down to a T section in the Return pipe for the filling loop then onto the 2 way valves in the lower part of the airing cupboard …i could add a pictue that would explain the layout much better… if thats possible on youtube ?. .any advice /help would be much appreciated .

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