I had this exact issue in house I bought where the plumbing was converted to a pressurised hot water tank for a loft extension with an extra en-suite bathroom. In summer some of the downstairs radiators got warm from the lockshield ends. Four British Gas engineers tried to fix it over 3 days. They changed the motorised valve twice! They couldn't work it out and left it unfixed. I then got in local independent heating engineer out who diagnosed the problem and fixed it with a non return valve on the hot water return as you described in a mornings work. Great video, spot on.
Absolutely spot on & exactly what was happening to my system! I tried everything to find out why this was happening, and it wasn't until I got rid of my heat only boiler, and changed to a combi boiler. The connection from the HW return was connected to the radiator return pipe under the floor. This was done when the house was built! Lazy plumbing indeed. Thank you 👍
I think you may be a wizard! This has been bugging me for ages and this was such a simple and clearly detailed explanation that you’ve made it seem completely obvious.
Hello Roger you are a great tutor for me because you speak my kind of uncomplicated language. I think a lot of tradesmen didn't have uncomplicated speakers like you when they were learning so they do their learning at the expense of their customers for many years.
Another invaluable piece of info, thanks for that. I was just re-watching an old video of yours regarding leaking stop taps and again a priceless titbit of info that's helped me out a few times. These sorts of videos that you and Robin do are a great source of information and are superb because of how short and straightforward they are. Many thanks again 👍
Another terrific video. Thanks. We have only a towel rail heated in the summer via the boiler and all rads are off but still get warm despite TRVs off. Rads upstairs and UFL down. As soon as it gets warm I shut the lock shield valve down and this sorts the problem. A new installation (including a low loss header (no idea what that adds)) but after watching this I'm getting them back in! Cheers
The summer operation towel rail is intentional but I suspect it is reverse circulating. They should be able to feel this on the pipes A non return valve should sort it out
Roger. Been around construction all my life coming from a building/construction family. Decided on plumbing as my profession. If i'd of had you as a mentor I'd of taken half the time to learn the knowledge. Took me a few years to grasp this particular fault find after my apprenticeship! Amazing explanation.
I had this, after I bought a run-down beautiful post-war end terrace in Scotland. It had a turret and spiral staircase, I loved it. Troubles made me sell it after a few years or updating, but the hidden issue was whenever the hot water cylinder was put to use, there was this trend to heat only the lower radiators in the house, not upstairs. I usually believe that once something’s done, I treat it as 100% until I find otherwise, this is one of the three times this has NOT held up! The system had two valves, but once I sketched it out I realised it needed a third. It had been relying on either the house being cold a lot, so some heating downstairs might not be a bad thing (!), or the owners had not noticed, etc. I fitted the third valve, which stopped the back-channel movement of hot water from the cylinder heating circuit, from going at all into the radiators backwards. It drove me nuts, but the present owner benefits as all of a sudden it’s not just a nuisance but an expensive one. As you will understand, the effect mainly was on radiators BELOW the level of the ‘head’ from the hot water entering and leaving the cylinder, which was perched in a corner cupboard of the kitchen, above the fridge. So, a three-motorised-valve system, instead of two, and it was perfect. Quite weird for me. Take care all. PS - have a laugh on me…the cost of the house when I bought it in 2003? £35,000 . 2 bedrooms plus a perfectly serviceable loft bedroom, and in fact this is what scuppered my letting plans - the government introduced a bedroom tax, and suddenly nobody moved because they;d have their benefits and home rooms scrutinised at that point, and this extra room was not ‘legit’. The council man said kindly ‘I am going to forget the request for retrospective approval, and put it in the drawer with the others’. I don;t understand hints, it’s terrible! He meant, I might be asked to return it to how it was, whatever that really means. It can mean, they examine the cables to see what date is stamped on them, but that’s a whole planning and building regs world of pain, let’s not go further.
Thanks Roger, that was a great explanation! (I actually have that minor issue with the rad nearest to the hot water tank) Although you explained the “wrong-way flow” and the one way valve solution very well, I think sometimes it’s the convection of the heat that creeps along the pipes, as opposed to an actual flow, so the one way valve may not necessarily function to prevent that…thank you for sharing 🙏
I’ve got that too, one rad beside the cistern is heating. No motorised splitter valve. The cistern return is linked upstairs leaving a single return pipe to the lower floor. Going to try an NRV in just that rad.
A decent explanation of a problem most plumbers/heating engineers have come across. Just moved house and it’s happening in mine too! 😀 Need to get round to draining it down and correcting before too much longer!
Roger, that might just explain my current problem! I had my combi boiler changed to unvented system and had it relocated in a different part of my house - have some but not all rads getting hot when calling for hot water . Plumber does not now what to do he has changed the 3 way motorised valve so hopefully when I show him your Video it will solve said problem! Thanks I appreciate the time and effort you put into producing these great videos. Ian
Very clear explanation Roger. I had this problem but with a different outcome so I will share it to help others. Rads getting hot when the heating was off but hot water on. Checked the motorised valve, all working correctly, even changed it, still no solution. Used my laser thermometer to see that the three port valve wasn't sealing. The rubber ball in the valve had just deteriorated and was allow some bypass. Changed the three port and the problem was solved.
That is a good idea to use the infrared thermometer. I did mention the motorised valve but dimissed it a bit, I should have given it more emphasis. Thanks for providing a bit of balance.
@@SkillBuilder To be honest, I have never come across it before and never thought it could be the valve. It took three visits, a lot of head scratching, half a dozen cups of tea and a fair few hobnobs.
Its only been like that for 8 years! We thought we were going crazy or the controls kept losing connection. Our underfloor heating warms the tank and our immersion cooks the underfloor heating. The pipe work looks a little more complex, but I can see the returns are fighting in an equal T. Thanks
Thanks Great video! our gravity fed Y system (with cyl) is a you have described, but has a small lock shield valve quarter to half turned on on the cyl pipe return to the boiler. The return pipe is in the correct place as you describe but I understand the addition of a lock shield valve also helps slow down the heating water in the cylinder coil so that the water in the coil is not going too fast as to "whizz" through the cyl and therefor heats the water as effectively as it can. I believe that the lock shield addition on the pipe return from the cyl also means the boiler should not receive back cyl coil water that is perhaps still too hot. NB. I'm Just in the process of tidying up the wiring centre (this is has been been a mess) with the larger Salus wiring centre ready for Hive to work on Home Kit. ( Grundfos UPS3 pump is set to Prop Pressure & working fine) Thanks again great video explanation.
Perfect explanation. Theres a reason for everything ... when someone like you can articulate that it makes the world a better place. Now time to find that out of place T, on the return from the cylinder. My heat is on in my home, and the thermostat is off. Im thinking to myself, WTF?! Def. subscribing
I'm going to start a campaign, to get you back on LBC radio " helps at hand phone in". Your brilliant and always liked listening to LBC when your radio show was on . Do you also remember the name of a motoring expert that was on LBC at roughly same time as your show? I think his first name was Gerrard?.
Thanks but LBC will never revive that show. They are now purely political and it works for them. The motoring expert is Gerrard Sauer. I was in touch with him recently, a brilliant, brilliant man.
I had this in a house in London. Radiators were hot when the boiler was switched off. Eventually I found the pipes going to the tenants house. The landlord had connected his radiators to his tenants house next door.
Great video I have this exact issue but only 1 radiator getting hot in the hallway instead of all of them…..could it still be this issue that you have explained?
October now. New boiler fitted in 3 floor house by Brit Gas last month. When heating goes off, top floor rads v hot. Same floor as emersion tank. Initially top floor rad long to heat. Now the opposite. Rads had power wash. Something stuck? What's the problem, do you think? Advice appreciated!
Interesting, thank you. Very clear explanation. Can I assume that if I've only had this problem for the first time this year, after fifteen years in the house, then it isn't reverse flow (because the plumbing layout hasn't suddenly changed), and that therefore I can assume that it's the motorised valve that's faulty?
Great advice, as an amateur I would have thought just of the 3 way valve. However what I would say is that if this problem suddenly occurs some time after installation, I would think it unlikely the install problem that you describe as it would have been like it from the start....No?
Just a thought to bear in mind perhaps there could have been a build up of magnetite some where inside the system near or at the three port valve / pump etc causing some obstruction / sticking if it's years after installation. May be Check with a magnet if you can on the copper pipe. Apparently Sentinel X100 or similar is supposed to help reduce magnetite build up esp with a Magnetic type "filter" regularly flushed or cleaned... as I say just a thought! 😀
Hi roger Great channel and video If i just have one radiator getting hot on the first floor when boiler on the ground floor how do i solve the issue ? Will i still need to lift boards to access pipework ?
Thanks for this. One question: isn’t the water coming out of the tank on the return cold? Even with reverse circulation, how do the radiators get warm?
Bravo! Another nice video. Honest & true. Thanks. Yes now that you have reminded me I have heard about this reverse flow phenomenon. There's another similar possibility isn't there? To do with the header tank feed thermo-siphoning. So you feed it in BELOW the return from a sort of U bend so that the heated water cannot rise. Anyway my heating has worked fine for 17 years but this Summer the rads are getting slightly warm when there is a HW demand, I thought it must be the valve. But is it the ball or the motor? Should I bite the bullet and replace both bits of it? Can the ball be fixed in any way? Why would it get stuck or not seat?
I had the exact same issue on the same set up but it was the valve that had failed in my case. Another well explained & informative explanation Roger.👍👍
Excellent timing for me Roger, I'd planned to replace my 3-valve this week to solve this exact problem and now I'm wondering if the problem is as you described. thanks!
If it has stopped then it is the valve. I think I unwitingly gave the reverse circulation too much weight. Thge important thing is that there is a simple way to find out which problem it is.
Hi Roger, i love the channel. Could you do a video with a diagram like this one for a dual system please? I had a guy do the job for me last year but I know its not right, he just connected stove back boiler into current system fueled by gas. I was advised he should have used a dual coil cylinder with seperate feed from attic tank and seperate overflow. Also, I realised that if I get a power cut my pump on the solid fuel doesnt work. He also has no non return between systems so when running gas I am heating the water in the back boiler aswel as the radiators in the same room. I would like a professional drawing so I can make sure the job is done right this time round. Cheers for the content, it s good to see professionals at work taking pride in what they do.
You don't have to have a dual coil cylinder if you have two separate heating appliances doing hot water cylinder+ heating. In the case of solar panels heating hot water yes you'd opt for a dual coil. In the case of two heating appliances for instance an older boiler that only heats a system up to 55c and a new one that's nominal operating temp would be 65c often the older boiler would be satisfied and not come on. Then to stop that boiler being heated you would just use a pipe stat linked to a 2-port valve to stop the flow through the appliance. The more important thing I'd be asking is - normally if the power cuts any modern boiler will stop functioning and the boiler is in control of the pump to stop it potentially overheating and going bang. If the back boiler on the stove is solid fuel you also run the risk of that issue. Also it may be capable of gravity circulation but all hot water cylinders now are legally required to be pumped on the primary side. Honestly though without a site visit to assess what you actually want/require it's impossible to give a drawing.
@@effervescence5664 Hi Mark, thanks for the reply, I am in Ireland so I don't know if reg's are the same. I already had a gas boiler closed system, and wanted a solid fuel stove. When I bought it, the builders merchant told me I would need a separate feed from tank and overflow, which would allow for expansion should the pump fail, no valve or restriction on expansion pipe and it should be 1 inch. Then have a non return valve connecting one coil to the other so the gas fuel circuit has all the radiators bar one, and wont heat the solid fuel side, and the solid fuel side has no restriction, one radiator for expansion and will heat the gas circuit aswel, as you said, modern gas boiler wont kick in with thermostat. I will say, I am not a plumber, the building merchant more than likely not a plumber so I really only have a very basic understanding, not knowledge or experience. When I got it done there were very few plumbers registered for solid fuel and none registered for both. He said it was fine to just tee into existing flow and return and change to vented system. I am doing the house up now and don't want to tear the gaff apart should a pipe go bang, or if I try to sell down the line I could have problems. System is working, and I will have a plumber inspecting it for me during works. My doubts only arise from the two differing opinions of the installer and supplier.
Hi Steve I will do something on this even though it is niche. I had one in my house but it was such a headache that I took it out and returned to a conventional system. I did quite a lot of them on wood burners in country locations but they were also prone to condensation on the back boiler which caused them to rot like pears.
@@SkillBuilder Cheers, I appreciate that, I'll know if my plumber is a chancer or not. Look forward to it, I'll share it on and try and get you some more subs.
@@effervescence5664 You need a "neutraliser", a neutral point which supplies all the heating appliances thus equalising pressures in all circumstances. It's just a common tank where all the supplies for the heating appliances are fed from. See: dunsleyheat.co.uk/neutralizer.html
Brilliant as usual, we have just had this happen tonight 1st time in 6 years. Turned off the rads on the control unit and let's see what happens tomorrow.
Excellent tuition. I have written this all down to grasp every word you have said. Now ... I have a combi boiler, not a cylinder/hot water tank. Can you please explain what is going wrong, when my heating comes on (radiators get hot) when my programme is CH OFF. What causes this? I turn my CH OFF and wake up in the morning to boiling radiators! Not good! Thank you.
EASIER and CHEAPER: Just close the individual radiator valves (the manual one) when the winter is gone. It takes 10 seconds for each radiator. No costs, no noise, the best solution indeed.
I have had problems with my entrance heating. I have had 3 new 3 valve changed. I think it is now, after looking at our youtube I think it is revers circulation problem? My question is could you just change around the valves on the radiators? I had a new boiler and tank fitted 2 years ago. Can you give me some advise?
Thank you for the really useful videos. I had reverse circulation on my downstairs radiators. This was resolved my fitting a non- return valve. However the issue now is that when i have both the Heating and Hot water on at the same time, the downstairs radiators are not warming up? Any ideas what it could be? Could it be there is too much resistance because of the non return valve?
Thanks for your fantastic video, I have come across a problem with my bioler, can you please help. So basiclly the bioler is controlled via a Hive system, I have hot water scheduled for 30 minutes everyday which is sufficient for everyones usage. The bioler has its own mind and will turn on and off on its own despite the fact that the controller is turned off for both hot water and central heating. I checked the routine, and it seems to be: it will turn itself on every 3 minutes for 1 minute, then shut off for 3 minutes until the next circle. When it's on, water circulates through the pipes, and no radiators are hot. It looks like the water cylinder is calling the bioler to wake up? After an overnight power off from the mains to the bioler, the first start up seems much longer than 1 minutes, and that is when hot water not scheduled to start up at all. Your help is much appreciated. Thanks in advance!
I have this problem really great to understand why! My DIY solution - the radiator closest to the cylinder I switch off in summer seems to stop the reverse flow.
I've just come across this problem. Ive had a plumber in as one of the radiators wasn't heating up. He said there was a blockage and used some type of sucking device and now the radiator is working again. But since he's done this, a few of my other radiators (ones closest to the boiler) are getting warm when the hot water is on. Never had this problem before.
Great explanation. We bought a house from a plumber. He's done all sorts of clever hacks and we have hot bathroom radiators (the two closest to the airing cupboard/hot water cylinder) pretty much all the time, even during summer heatwaves 🙂 Keeps the towels nice and dry at least...
@@SkillBuilder How does it work? I am sure you could an entire mini-series on how my house is plumbed. It's a maze of pipes and tanks and valves, half of them unused...
I have just got the same problem, atleast I have got an idea 💡 what would be the problem. Now I know what is the solutions. Thank you for making knowledgeable video. Blessings
Hi Many thanks for this! I m not sure but I have similar problem. My boiler is only 3 yrs old. since we change the boiler my top floor radiator of one of the bedroom and bathroom including tap water r hot at middle of night @3am. The pipes of all radiators r hot of all upper floor. The valve has been changed twice. But the problem was still there. Our Nest shows the heating is off but these radiators and tap water r still hot. Gas engineer checked and changed that valve again last week, cleaned and drained the system. Now He doesn’t know why the radiators and tap water is also hot enough to wash dishes even with hot water off for the whole week. According to him if the Nest reading is the heating is off then there is nothing wrong with the system and he can not do nothing else. Do u think is it possible to set up the freezing temperature at higher levels for the boiling to start at the higher temperature. I don’t know whether it will make sense to u or not what I m trying to explain? But i desperately need help from people like urself! Best regards Harinder Kaur
so from a non skilled DIY man (Who wont be touching his boiler!) I have the same issue, but I dont have a water tank, just the ISAR HE35 combi-boiler. Situated on the kitchen wall, and the radiator directly upstairs (probably the first radiator on the system) get warm even in the hot summer. Problem is the dam boiler fires up every now and again I suppose due to some funky programming on the PCB? Does the backflow of water you explained in the video cause any issues?
Hi Roger, we have a baxi 428 combi and the central heating flow pipe gets very hot when the hot water is on even though the heating is off. Should this happening? If not, what would be the cause please? I did have a baxi engineer out as I felt the hot water wasn’t as hot as it used to be but he just said the weather is colder and dismissed my concern over the CH pipe getting hot. Any advice would be appreciated. Thanks
Roger, thank you for this video. Very informative. Can you tell me please…..if the radiators are hot when the boiler (heating) is off, is it still putting a charge on your gas bill even though the boiler is off? Thank you! 😊
@@SkillBuilder thank you very much. My bills are extraordinarly high. I live alone in a flat that’s compact and doesn’t get that cold. I wondered why so thank you very much for answering this question. I had my boiler serviced recently. Should the gas engineer have picked up on this warmth of the radiators by looking at the boiler, without me telling him?
Hi, great video; would this problem occur If an extra radiator has been installed and that one is the only rad getting partially warm when the hot water is regenerating? Kind regards
This is my favourite type of video, simple but really good. I think explaining stuff like this is your forte! (Not to say the other types aren’t good, but really like this format)
We have a gravity feed hydronic system that does not have electricity running to the boiler. The explanation I got was that the pilot produces millivolts of charge and if the charge is interrupted somehow the thermostat calls for the heat exchanger to ignite. Since there is no electricity the thermostat can't be turned off just down. The thermostat will call for heat even with no electricity.
Great video, Im an amatuer but I thought the pump in the airing cupboard pumped it one way? so i don't understand!!...Also, does the 3 port valve let the hot through to the radiators when the flow is reversed, hence the heating on when I don't want it. I'm not sure which way my flow was at the radiators so i can't test by feel. i've replaced the 3 port valve motor following your tutorial and the problem came back after a while so i replaced the pcb and still got the problem.....could it be the internals of the valve body itself sticking open? would appreciate any help.
I wonder if a good way to describe the correct positioning of that final return tee is that the cylinder return flow pressure at the tee is not greater than the total combined radiator return flow pressure, and that directs the cylinder return flow only one way - straight back to the boiler.
appreciate it I have the opposite my CH is coming on when I put on the HW only It is not reaching the temp I would expect of 60 to 65deg c but only 54 deg c and no more Preumably because the rads are taking its potential to I keep trying to fix this to no avail Mr Bisby may i ask one thing😊 my HW cylinder return is 22mm buthas been reduced to 15mm and I do not think its connected to the return There is a H piece 22mm twin pipe connected to CH side but one of the pipes has an offset 15mm to the 15 mm pipe that is where it connects Could you help me identify the 15mm pipe if its the boiler return or a CH return and how do I find the primary return
Roger, may I ask a question please? I've built an extension that I would like to run the GCH from the house to. I may need a bigger boiler but that's another issue. My question is could I take the extension return directly into the boiler return, close to the boiler, and the hot feed for the extension from the house radiator circuit feed? Thank you and thanks for this video. Anthony
Great no nonsense explanations - thanks Roger. My problem is the central heating pump comes on even when only hot water is selected. Motorized valve seems to be working and the programmer is only about a year old. Could it be the programmer is wired incorrectly? Anybody?
Hi this has just started with mine. I have a combi boiler with a mega flow system and I have switched off the heating but have kept the hot water on a schedule. Now when the hot water comes on the heating comes on as well. The heating comes on at full blast. Does this mean my motorised valve need replacing?
on a heat pump system one radiator is hot in one room and the one in the other room cold in the room beside it I turned off all radiators on that line except the cold one to try forse water to it but the hot radiator came on as well how could this happen thank u
I have had exactly this happening for years. i have had at least 4 new micro switches fitted during that time. Strangely(or maybe not when you explain), a new switch seems to solve it for a while. But sure enough it comes back again after maybe 2 yrs or so. Not sure how i now try and get my regular service guy to tackle this without him getting all manny about me trying to tell him what really needs doing(he was not the one who fitted the system 20 yrs ago}. He is close to retirement so i might take the cowards diplomatic route and speak to a young plumber i now know who is keen to get more work!!. I suspect there is more chance that the younger guy might be the way forward for me. Thanks, invaluable info/advice.
Thanks for that. I've been going crazy for the past week trying to understand what is going on with this three-way valve and Honeywell actuator on my heating system.
Hi Roger, great channel. Only thing I do different is run the heating to define flow and returns after I've witnessed the problem with just the hot water on. If the same pipe gets hotter it's the valve leaking, if the other one does it's reverse circulation.
Very useful information. Do you have a video covering a constant low level hum from a SSE 330 boiler - even when the CH and HW are off (at night)? Thanks
FANTASTIC nice and simple I also had a run in with British Gas 6 engineers came round still could fix my problem they couldn’t run a bath shame the is not enough good plumber like yourself. Great videos 👍👍👍👍
I’ve just recently developed this problem with a 10 year old Worcester Bosch combi boiler. I don’t have a cylinder or any visible pumps or valves. Presumably then it’s something within the boiler not working as it should, or did previously. Any views or advice before I call out my boiler servicing engineer would be welcome. Thank you.
Even with the rads all tee'd before the primary return is there still not the chance of the water working back some, or would there be some sort of back pressure preventing it. Would it be reasonable to put a one-way valve in too, above the tee, but before the tank return?
Hi I’ve got a combi boiler Worcester and my bathroom radiator got warm at top but not at bottom, couldn’t understand it, but it happened in our heatwave we had not long ago
I have a problem! In in a flat and everytime next door turns on their radiators all mine come on! Even though all my radiators are switched off manually they are all on the snowflake setting ❄ it gets massively hot in my apartment I cannot even cope with the heat all the time. How does this happen please?
Of course that's what it is! Christ on a bike I've been addled about this problem for three years. Even thought about emailing you about it for your Q&A. Right, I'm all over that this weekend. I think the none return valve will be the solution.
What about bypassed towel radiators? Have come across this when towel radiator heats both on Hot Water and Central Heating. Is that still an acceptable installation technique?
Yes that summer operation of a towel rail is still common on stored water systems. It is hard to achieve with a combi so an electric element is placed in the towel rail.
Thanks for your video, which is helpful. I have a combit bolier, I can't turn off one of radiators. Could I ask what could be the cause of the problem? Many thanks.
I had the opposite happen wherby the rads stopped getting heat when the heating was on.The motorised valve motor was also making a buzzing noise.I replaced it and wired it in correctly and all was good.The only faff is part draining the system first and then bleeding an rebalancing afterwards.Changing the valve took about an hour all in with wiring but overall the whole job took about 4 hours.
What would it be if you have a combi boiler/no hot water tank and when the hot what runs, the radiators heat up. I believe my boiler also does not have a 2 port valve which most folk point to. Boiler is a worcester 28i, 8/10 years old
Skill Builder that’s cause you spend more time with us knowledge-hungry “builders”, roger! Get the white board out and show her in doors how you’re gonna spend more time with her, starting with a little trip to brighton 😎
Hi Roger, thanks so much. Our radiators do this but they get absolutely boiling hot in the summer not just warm, would it be the same issue ? It’s a new renovation so all pipework is new. I’ve had the plumber look at it but he couldn’t find anything wrong. Split system our underfloor heating downstairs is fine but all radiators on the 2nd thermostat system do it.
Hello Roger, I am Italian living in the UK and I am trying to get some understanding since I bought a house and had heating issues. I got a code on my Ideal boiler FA which is flow and return reversed. One engineer changed the pump abd the motor in the valve as radiators were hot on hot water only, nothing sorted. After him another changed all the 3 port valve showing me the dirt and the mechanism not working, it looks like I am not having warm radiators anymore(it's been just yesterday he fixed those) but FA code still flashing when on hot water only.At this stage don't really know what it could be :( causing it. When the FA goes on in the cylinder area pump/noise is on, it appears sometimes the C in blu and then fails again. If it wasn't for that FA the system looks like it's working fine...HELP PLEASE
Roger, the reverse circulation happens not to my radiators but to my taps. When I turn my water off at stop tap under sink, the cold water flows out then hot water continues to follow it out my hot water cylinder out of my tap??? The flow doesn't really stop. I had my boiler relocated last year and before this it never did it. When you turn the stop tap off and open a downstairs tap cold water should flow then stop. Can you help with this?
Would it not also be possible to fit another motorised valve to close off the Central Heating Return flow pipes when the Hot Water Cylinder is calling for heat.
We should also explain that in some properties the bathroom rad or towel rail has been purposely put on a separate circuit so as this can be used at the same time as the hot water is running on its own simply to warm or dry towels.
Hi Rodger Great informative video as always. I also have this issue but with my combi boiler which was only installed a year ago is there any different issues with this or is it a case where as you mentioned they have joined the return in a similar place ? Thanks
@@SkillBuilder it is most likely a problem with your combi boiler. The boiler has a diverted valve also which can get jammed between heating and hot water. Also your plate heat exchanger could be full of debris/sludge forcing water down your heating circuit.
Learnt something new! My only protest is the non return valve. This will cause problems when we do powerflush of the system and alternate the direction of flow left and right. It's obviously not going to allow that. There must be another way without requiring non return valves.
Roger please help… my combi boiler is Set off at the thermostat, (8degrees) yet the flow temperature of the boiler when it drops below 30c kicks the boiler in every 10 mins to keep it above 30c… the wireless thermostat doesn’t seem to be controlling the boiler maybe? Could it be the thermostat or the wireless receiver that is wired in to the boiler maybe? Any help would be appreciated my bills have just gone up to £400 a month. Thanks in advance Sean
Although an excellent video explaining reverse circulation, the critical question to ask the customer is “has this problem always occurred or is it a new phenomenon”. Reverse circulation is caused by poor system design and won’t just happen all of a sudden! If rads are getting hot with just a H/W demand is a new problem it’s more than likely Motorised valve letting by. Some valves are more notorious for this than others!! Top marks for the explanation of the common return though 👍
you are so right. I know some people put up with this problem for years and some discover it when moving in to a new property but a few questions will lead you there faster.
Thanks for this video, I have been wondering why this has been happening in my house for the 7 years I've lived here. I assumed it was whoever did the plumbing being lazy/ignorant and now I know that is more than likely the case.
I had this exact issue in house I bought where the plumbing was converted to a pressurised hot water tank for a loft extension with an extra en-suite bathroom. In summer some of the downstairs radiators got warm from the lockshield ends. Four British Gas engineers tried to fix it over 3 days. They changed the motorised valve twice! They couldn't work it out and left it unfixed. I then got in local independent heating engineer out who diagnosed the problem and fixed it with a non return valve on the hot water return as you described in a mornings work. Great video, spot on.
I have exactly the same circumstance as you Kenneth! Am about to do the heat check now before I call out the plumber
Absolutely spot on & exactly what was happening to my system! I tried everything to find out why this was happening, and it wasn't until I got rid of my heat only boiler, and changed to a combi boiler. The connection from the HW return was connected to the radiator return pipe under the floor. This was done when the house was built!
Lazy plumbing indeed.
Thank you 👍
An excellent teacher, clear and precise and has a way of explaining in detail that is very helpful to many.
I think you may be a wizard! This has been bugging me for ages and this was such a simple and clearly detailed explanation that you’ve made it seem completely obvious.
Hello Roger you are a great tutor for me because you speak my kind of uncomplicated language. I think a lot of tradesmen didn't have uncomplicated speakers like you when they were learning so they do their learning at the expense of their customers for many years.
Thanks for that. I try to stay clear of BS numbers and all that stuff because I think that is what a lot of lecturers become obssesed with
Another invaluable piece of info, thanks for that. I was just re-watching an old video of yours regarding leaking stop taps and again a priceless titbit of info that's helped me out a few times. These sorts of videos that you and Robin do are a great source of information and are superb because of how short and straightforward they are. Many thanks again 👍
Thanks for your comment on stop taps, I've just stop mine leaving
Another terrific video. Thanks. We have only a towel rail heated in the summer via the boiler and all rads are off but still get warm despite TRVs off. Rads upstairs and UFL down. As soon as it gets warm I shut the lock shield valve down and this sorts the problem. A new installation (including a low loss header (no idea what that adds)) but after watching this I'm getting them back in! Cheers
The summer operation towel rail is intentional but I suspect it is reverse circulating. They should be able to feel this on the pipes A non return valve should sort it out
Roger. Been around construction all my life coming from a building/construction family. Decided on plumbing as my profession. If i'd of had you as a mentor I'd of taken half the time to learn the knowledge. Took me a few years to grasp this particular fault find after my apprenticeship! Amazing explanation.
I had this, after I bought a run-down beautiful post-war end terrace in Scotland. It had a turret and spiral staircase, I loved it. Troubles made me sell it after a few years or updating, but the hidden issue was whenever the hot water cylinder was put to use, there was this trend to heat only the lower radiators in the house, not upstairs. I usually believe that once something’s done, I treat it as 100% until I find otherwise, this is one of the three times this has NOT held up! The system had two valves, but once I sketched it out I realised it needed a third. It had been relying on either the house being cold a lot, so some heating downstairs might not be a bad thing (!), or the owners had not noticed, etc.
I fitted the third valve, which stopped the back-channel movement of hot water from the cylinder heating circuit, from going at all into the radiators backwards. It drove me nuts, but the present owner benefits as all of a sudden it’s not just a nuisance but an expensive one. As you will understand, the effect mainly was on radiators BELOW the level of the ‘head’ from the hot water entering and leaving the cylinder, which was perched in a corner cupboard of the kitchen, above the fridge. So, a three-motorised-valve system, instead of two, and it was perfect. Quite weird for me. Take care all.
PS - have a laugh on me…the cost of the house when I bought it in 2003? £35,000 . 2 bedrooms plus a perfectly serviceable loft bedroom, and in fact this is what scuppered my letting plans - the government introduced a bedroom tax, and suddenly nobody moved because they;d have their benefits and home rooms scrutinised at that point, and this extra room was not ‘legit’. The council man said kindly ‘I am going to forget the request for retrospective approval, and put it in the drawer with the others’. I don;t understand hints, it’s terrible! He meant, I might be asked to return it to how it was, whatever that really means. It can mean, they examine the cables to see what date is stamped on them, but that’s a whole planning and building regs world of pain, let’s not go further.
Thanks Roger, that was a great explanation! (I actually have that minor issue with the rad nearest to the hot water tank) Although you explained the “wrong-way flow” and the one way valve solution very well, I think sometimes it’s the convection of the heat that creeps along the pipes, as opposed to an actual flow, so the one way valve may not necessarily function to prevent that…thank you for sharing 🙏
I’ve got that too, one rad beside the cistern is heating. No motorised splitter valve. The cistern return is linked upstairs leaving a single return pipe to the lower floor. Going to try an NRV in just that rad.
A decent explanation of a problem most plumbers/heating engineers have come across. Just moved house and it’s happening in mine too! 😀 Need to get round to draining it down and correcting before too much longer!
its always a joy to listen to someone who really knows his onions! Brilliant explanation
Roger job spot on, well explained. The time taken is worth it 👌.
Thank you. I watched my previous efforts and thought it was just not clear enough. I am glad it worked in the end.
Roger, that might just explain my current problem! I had my combi boiler changed to unvented system and had it relocated in a different part of my house - have some but not all rads getting hot when calling for hot water . Plumber does not now what to do he has changed the 3 way motorised valve so hopefully when I show him your Video it will solve said problem! Thanks I appreciate the time and effort you put into producing these great videos. Ian
Let's hope you can get to the bottom of it.
Very clear explanation Roger.
I had this problem but with a different outcome so I will share it to help others.
Rads getting hot when the heating was off but hot water on.
Checked the motorised valve, all working correctly, even changed it, still no solution.
Used my laser thermometer to see that the three port valve wasn't sealing. The rubber ball in the valve had just deteriorated and was allow some bypass.
Changed the three port and the problem was solved.
That is a good idea to use the infrared thermometer. I did mention the motorised valve but dimissed it a bit, I should have given it more emphasis. Thanks for providing a bit of balance.
@@SkillBuilder To be honest, I have never come across it before and never thought it could be the valve.
It took three visits, a lot of head scratching, half a dozen cups of tea and a fair few hobnobs.
Its only been like that for 8 years! We thought we were going crazy or the controls kept losing connection.
Our underfloor heating warms the tank and our immersion cooks the underfloor heating.
The pipe work looks a little more complex, but I can see the returns are fighting in an equal T.
Thanks
Love these SB videos. Amazing knowledge and very clear when explaining how things work. I have this issue so know what to look for now. Thank you.
Great explanation, have this problem, rads get a little warm when just HW on, installed by a professional as well....!
Some professionals don't know about reverse circulation. It is taught at college but not everyone goes to college.
Thanks Great video! our gravity fed Y system (with cyl) is a you have described, but has a small lock shield valve quarter to half turned on on the cyl pipe return to the boiler. The return pipe is in the correct place as you describe but I understand the addition of a lock shield valve also helps slow down the heating water in the cylinder coil so that the water in the coil is not going too fast as to "whizz" through the cyl and therefor heats the water as effectively as it can. I believe that the lock shield addition on the pipe return from the cyl also means the boiler should not receive back cyl coil water that is perhaps still too hot. NB. I'm Just in the process of tidying up the wiring centre (this is has been been a mess) with the larger Salus wiring centre ready for Hive to work on Home Kit. ( Grundfos UPS3 pump is set to Prop Pressure & working fine) Thanks again great video explanation.
I learn a lot from these videos. In fact, I learn a lot from all your videos. Cheers Roger 👍
Perfect explanation. Theres a reason for everything ... when someone like you can articulate that it makes the world a better place. Now time to find that out of place T, on the return from the cylinder. My heat is on in my home, and the thermostat is off. Im thinking to myself, WTF?! Def. subscribing
I'm going to start a campaign, to get you back on LBC radio " helps at hand phone in". Your brilliant and always liked listening to LBC when your radio show was on .
Do you also remember the name of a motoring expert that was on LBC at roughly same time as your show? I think his first name was Gerrard?.
Thanks but LBC will never revive that show. They are now purely political and it works for them. The motoring expert is Gerrard Sauer. I was in touch with him recently, a brilliant, brilliant man.
@@SkillBuilder Many thanks for your reply.
I had this in a house in London. Radiators were hot when the boiler was switched off. Eventually I found the pipes going to the tenants house. The landlord had connected his radiators to his tenants house next door.
That is a new one on me but I did see a flat in a conversion block that was using the neighbour's gas supply.
Great video I have this exact issue but only 1 radiator getting hot in the hallway instead of all of them…..could it still be this issue that you have explained?
October now. New boiler fitted in 3 floor house by Brit Gas last month. When heating goes off, top floor rads v hot. Same floor as emersion tank. Initially top floor rad long to heat. Now the opposite. Rads had power wash. Something stuck? What's the problem, do you think? Advice appreciated!
Interesting, thank you. Very clear explanation. Can I assume that if I've only had this problem for the first time this year, after fifteen years in the house, then it isn't reverse flow (because the plumbing layout hasn't suddenly changed), and that therefore I can assume that it's the motorised valve that's faulty?
Yes that it the most likely scenario.
Great advice, as an amateur I would have thought just of the 3 way valve. However what I would say is that if this problem suddenly occurs some time after installation, I would think it unlikely the install problem that you describe as it would have been like it from the start....No?
Just a thought to bear in mind perhaps there could have been a build up of magnetite some where inside the system near or at the three port valve / pump etc causing some obstruction / sticking if it's years after installation. May be Check with a magnet if you can on the copper pipe. Apparently Sentinel X100 or similar is supposed to help reduce magnetite build up esp with a Magnetic type "filter" regularly flushed or cleaned... as I say just a thought! 😀
Hi roger
Great channel and video
If i just have one radiator getting hot on the first floor when boiler on the ground floor how do i solve the issue ?
Will i still need to lift boards to access pipework ?
Thanks for another great video, I have this problem but I have a combi boiler. Any ideas?
It will be the divertor valve in the boiler that is letting by.
Thanks for this. One question: isn’t the water coming out of the tank on the return cold? Even with reverse circulation, how do the radiators get warm?
Bravo! Another nice video. Honest & true. Thanks. Yes now that you have reminded me I have heard about this reverse flow phenomenon. There's another similar possibility isn't there? To do with the header tank feed thermo-siphoning. So you feed it in BELOW the return from a sort of U bend so that the heated water cannot rise.
Anyway my heating has worked fine for 17 years but this Summer the rads are getting slightly warm when there is a HW demand, I thought it must be the valve. But is it the ball or the motor? Should I bite the bullet and replace both bits of it? Can the ball be fixed in any way? Why would it get stuck or not seat?
I had the exact same issue on the same set up but it was the valve that had failed in my case. Another well explained & informative explanation Roger.👍👍
I can be the valve but it is easy to feel if it is letting by. I am amazed when plumbers just replace it without doing that.
Excellent timing for me Roger, I'd planned to replace my 3-valve this week to solve this exact problem and now I'm wondering if the problem is as you described. thanks!
If it has stopped then it is the valve. I think I unwitingly gave the reverse circulation too much weight. Thge important thing is that there is a simple way to find out which problem it is.
Hi Roger, i love the channel. Could you do a video with a diagram like this one for a dual system please? I had a guy do the job for me last year but I know its not right, he just connected stove back boiler into current system fueled by gas. I was advised he should have used a dual coil cylinder with seperate feed from attic tank and seperate overflow. Also, I realised that if I get a power cut my pump on the solid fuel doesnt work. He also has no non return between systems so when running gas I am heating the water in the back boiler aswel as the radiators in the same room. I would like a professional drawing so I can make sure the job is done right this time round. Cheers for the content, it s good to see professionals at work taking pride in what they do.
You don't have to have a dual coil cylinder if you have two separate heating appliances doing hot water cylinder+ heating. In the case of solar panels heating hot water yes you'd opt for a dual coil. In the case of two heating appliances for instance an older boiler that only heats a system up to 55c and a new one that's nominal operating temp would be 65c often the older boiler would be satisfied and not come on. Then to stop that boiler being heated you would just use a pipe stat linked to a 2-port valve to stop the flow through the appliance.
The more important thing I'd be asking is - normally if the power cuts any modern boiler will stop functioning and the boiler is in control of the pump to stop it potentially overheating and going bang. If the back boiler on the stove is solid fuel you also run the risk of that issue. Also it may be capable of gravity circulation but all hot water cylinders now are legally required to be pumped on the primary side. Honestly though without a site visit to assess what you actually want/require it's impossible to give a drawing.
@@effervescence5664 Hi Mark, thanks for the reply, I am in Ireland so I don't know if reg's are the same. I already had a gas boiler closed system, and wanted a solid fuel stove. When I bought it, the builders merchant told me I would need a separate feed from tank and overflow, which would allow for expansion should the pump fail, no valve or restriction on expansion pipe and it should be 1 inch. Then have a non return valve connecting one coil to the other so the gas fuel circuit has all the radiators bar one, and wont heat the solid fuel side, and the solid fuel side has no restriction, one radiator for expansion and will heat the gas circuit aswel, as you said, modern gas boiler wont kick in with thermostat.
I will say, I am not a plumber, the building merchant more than likely not a plumber so I really only have a very basic understanding, not knowledge or experience. When I got it done there were very few plumbers registered for solid fuel and none registered for both. He said it was fine to just tee into existing flow and return and change to vented system. I am doing the house up now and don't want to tear the gaff apart should a pipe go bang, or if I try to sell down the line I could have problems. System is working, and I will have a plumber inspecting it for me during works.
My doubts only arise from the two differing opinions of the installer and supplier.
Hi Steve
I will do something on this even though it is niche. I had one in my house but it was such a headache that I took it out and returned to a conventional system. I did quite a lot of them on wood burners in country locations but they were also prone to condensation on the back boiler which caused them to rot like pears.
@@SkillBuilder Cheers, I appreciate that, I'll know if my plumber is a chancer or not. Look forward to it, I'll share it on and try and get you some more subs.
@@effervescence5664 You need a "neutraliser", a neutral point which supplies all the heating appliances thus equalising pressures in all circumstances. It's just a common tank where all the supplies for the heating appliances are fed from.
See: dunsleyheat.co.uk/neutralizer.html
Brilliant as usual, we have just had this happen tonight 1st time in 6 years. Turned off the rads on the control unit and let's see what happens tomorrow.
Excellent tuition. I have written this all down to grasp every word you have said. Now ... I have a combi boiler, not a cylinder/hot water tank. Can you please explain what is going wrong, when my heating comes on (radiators get hot) when my programme is CH OFF. What causes this? I turn my CH OFF and wake up in the morning to boiling radiators! Not good! Thank you.
EASIER and CHEAPER: Just close the individual radiator valves (the manual one) when the winter is gone. It takes 10 seconds for each radiator. No costs, no noise, the best solution indeed.
Also has the benfit of working the valve (TRV) as they are prone to sticking if not manually turned on and off ocassionaly
I have had problems with my entrance heating. I have had 3 new 3 valve changed. I think it is now, after looking at our youtube I think it is revers circulation problem?
My question is could you just change around the valves on the radiators?
I had a new boiler and tank fitted 2 years ago.
Can you give me some advise?
Thank you for the really useful videos. I had reverse circulation on my downstairs radiators. This was resolved my fitting a non- return valve. However the issue now is that when i have both the Heating and Hot water on at the same time, the downstairs radiators are not warming up? Any ideas what it could be? Could it be there is too much resistance because of the non return valve?
Thanks for your fantastic video, I have come across a problem with my bioler, can you please help.
So basiclly the bioler is controlled via a Hive system, I have hot water scheduled for 30 minutes everyday which is sufficient for everyones usage. The bioler has its own mind and will turn on and off on its own despite the fact that the controller is turned off for both hot water and central heating.
I checked the routine, and it seems to be: it will turn itself on every 3 minutes for 1 minute, then shut off for 3 minutes until the next circle.
When it's on, water circulates through the pipes, and no radiators are hot.
It looks like the water cylinder is calling the bioler to wake up? After an overnight power off from the mains to the bioler, the first start up seems much longer than 1 minutes, and that is when hot water not scheduled to start up at all.
Your help is much appreciated. Thanks in advance!
Fantastic video and explanation, I wonder if anyone else thinks "Doh, I wish i has watched this before I started!"
I have this problem really great to understand why!
My DIY solution - the radiator closest to the cylinder I switch off in summer seems to stop the reverse flow.
That will work in most cases and with TRVs they will close in the summer anyway.
I've just come across this problem. Ive had a plumber in as one of the radiators wasn't heating up. He said there was a blockage and used some type of sucking device and now the radiator is working again. But since he's done this, a few of my other radiators (ones closest to the boiler) are getting warm when the hot water is on. Never had this problem before.
Great explanation. We bought a house from a plumber. He's done all sorts of clever hacks and we have hot bathroom radiators (the two closest to the airing cupboard/hot water cylinder) pretty much all the time, even during summer heatwaves 🙂 Keeps the towels nice and dry at least...
summer operation on towel rails is common.
@@SkillBuilder How does it work? I am sure you could an entire mini-series on how my house is plumbed. It's a maze of pipes and tanks and valves, half of them unused...
As usual you have done great work and explained your own experience to be helpful for others. Many thanks Roger.
I have just got the same problem, atleast I have got an idea 💡 what would be the problem. Now I know what is the solutions. Thank you for making knowledgeable video. Blessings
Hi
Many thanks for this! I m not sure but I have similar problem. My boiler is only 3 yrs old. since we change the boiler my top floor radiator of one of the bedroom and bathroom including tap water r hot at middle of night @3am. The pipes of all radiators r hot of all upper floor.
The valve has been changed twice. But the problem was still there. Our Nest shows the heating is off but these radiators and tap water r still hot. Gas engineer checked and changed that valve again last week, cleaned and drained the system. Now He doesn’t know why the radiators and tap water is also hot enough to wash dishes even with hot water off for the whole week. According to him if the Nest reading is the heating is off then there is nothing wrong with the system and he can not do nothing else.
Do u think is it possible to set up the freezing temperature at higher levels for the boiling to start at the higher temperature. I don’t know whether it will make sense to u or not what I m trying to explain?
But i desperately need help from people like urself!
Best regards
Harinder Kaur
Good one Roger 👍🏼
My shower mixer doesn’t go completely cold on the coldest setting. Is that likely to be design or installation error?
I also like a cold shower. You need to callibrate it. Usually it is a case of taking the knob off and moving the stops.
so from a non skilled DIY man (Who wont be touching his boiler!) I have the same issue, but I dont have a water tank, just the ISAR HE35 combi-boiler. Situated on the kitchen wall, and the radiator directly upstairs (probably the first radiator on the system) get warm even in the hot summer. Problem is the dam boiler fires up every now and again I suppose due to some funky programming on the PCB? Does the backflow of water you explained in the video cause any issues?
Hi Roger, we have a baxi 428 combi and the central heating flow pipe gets very hot when the hot water is on even though the heating is off. Should this happening? If not, what would be the cause please? I did have a baxi engineer out as I felt the hot water wasn’t as hot as it used to be but he just said the weather is colder and dismissed my concern over the CH pipe getting hot. Any advice would be appreciated. Thanks
Hi Roger, Thanks for the clear explanation. I have that problem and never really found a clear explanation until I saw your video! Thanks
Roger, thank you for this video. Very informative. Can you tell me please…..if the radiators are hot when the boiler (heating) is off, is it still putting a charge on your gas bill even though the boiler is off? Thank you! 😊
Yes if they remain hot for more than 20 minutes it is costing you money
@@SkillBuilder thank you very much. My bills are extraordinarly high. I live alone in a flat that’s compact and doesn’t get that cold. I wondered why so thank you very much for answering this question.
I had my boiler serviced recently. Should the gas engineer have picked up on this warmth of the radiators by looking at the boiler, without me telling him?
Hi, great video; would this problem occur If an extra radiator has been installed and that one is the
only rad getting partially warm when the hot water is regenerating?
Kind regards
This is my favourite type of video, simple but really good. I think explaining stuff like this is your forte! (Not to say the other types aren’t good, but really like this format)
Thanks Mat. How is the house coming on.
Have this same issue but only with my living room radiator. I’ll give this a go!
We have a gravity feed hydronic system that does not have electricity running to the boiler. The explanation I got was that the pilot produces millivolts of charge and if the charge is interrupted somehow the thermostat calls for the heat exchanger to ignite. Since there is no electricity the thermostat can't be turned off just down. The thermostat will call for heat even with no electricity.
3 Plumbers in four years and I think you’ve solved my problem!
Great video, Im an amatuer but I thought the pump in the airing cupboard pumped it one way? so i don't understand!!...Also, does the 3 port valve let the hot through to the radiators when the flow is reversed, hence the heating on when I don't want it. I'm not sure which way my flow was at the radiators so i can't test by feel. i've replaced the 3 port valve motor following your tutorial and the problem came back after a while so i replaced the pcb and still got the problem.....could it be the internals of the valve body itself sticking open? would appreciate any help.
I have two 2 way motorised valves, both brand new, when i want just hot water, they radiators heat up, any ideas, both valves are working ok.
I wonder if a good way to describe the correct positioning of that final return tee is that the cylinder return flow pressure at the tee is not greater than the total combined radiator return flow pressure, and that directs the cylinder return flow only one way - straight back to the boiler.
appreciate it
I have the opposite my CH is coming on when I put on the HW only
It is not reaching the temp I would expect of 60 to 65deg c but only 54 deg c and no more
Preumably because the rads are taking its potential to
I keep trying to fix this to no avail
Mr Bisby may i ask one thing😊 my HW cylinder return is 22mm buthas been reduced to 15mm and I do not think its connected to the return There is a H piece 22mm twin pipe connected to CH side but one of the pipes has an offset 15mm to the 15 mm pipe that is where it connects
Could you help me identify the 15mm pipe if its the boiler return or a CH return and how do I find the primary return
Roger, may I ask a question please? I've built an extension that I would like to run the GCH from the house to. I may need a bigger boiler but that's another issue. My question is could I take the extension return directly into the boiler return, close to the boiler, and the hot feed for the extension from the house radiator circuit feed? Thank you and thanks for this video. Anthony
This video may actually answer my question??
Great no nonsense explanations - thanks Roger. My problem is the central heating pump comes on even when only hot water is selected. Motorized valve seems to be working and the programmer is only about a year old. Could it be the programmer is wired incorrectly? Anybody?
Hi this has just started with mine. I have a combi boiler with a mega flow system and I have switched off the heating but have kept the hot water on a schedule. Now when the hot water comes on the heating comes on as well. The heating comes on at full blast. Does this mean my motorised valve need replacing?
Can I put zone valve on return as well. Connected together with the one on flow without connecting orange wire
yes
on a heat pump system one radiator is hot in one room and the one in the other room cold in the room beside it I turned off all radiators on that line except the cold one to try forse water to it but the hot radiator came on as well how could this happen thank u
I have had exactly this happening for years. i have had at least 4 new micro switches fitted during that time. Strangely(or maybe not when you explain), a new switch seems to solve it for a while. But sure enough it comes back again after maybe 2 yrs or so. Not sure how i now try and get my regular service guy to tackle this without him getting all manny about me trying to tell him what really needs doing(he was not the one who fitted the system 20 yrs ago}. He is close to retirement so i might take the cowards diplomatic route and speak to a young plumber i now know who is keen to get more work!!. I suspect there is more chance that the younger guy might be the way forward for me. Thanks, invaluable info/advice.
Thanks for that. I've been going crazy for the past week trying to understand what is going on with this three-way valve and Honeywell actuator on my heating system.
The same thing has happened to me
Hi Roger, great channel. Only thing I do different is run the heating to define flow and returns after I've witnessed the problem with just the hot water on. If the same pipe gets hotter it's the valve leaking, if the other one does it's reverse circulation.
Jim
Good way of explaining it but the same idea just the other way of coming at it.
Very useful information. Do you have a video covering a constant low level hum from a SSE 330 boiler - even when the CH and HW are off (at night)? Thanks
Excellent diagram and explanation of what can or might be problems. Thanks Rodger a little bit of knowledge is better than none👍👍👍
thanks, is this the same for a combi boiler?
No it is only for cylinders
any chance you could do a film about under floor heating converting normal radiator heating system if indeed this is possible
Can this issue only happen on 3 part valve or on S plan as well?
yes they are almost all spring return valves with the same motor
FANTASTIC nice and simple I also had a run in with British Gas 6 engineers came round still could fix my problem they couldn’t run a bath shame the is not enough good plumber like yourself. Great videos 👍👍👍👍
I’ve just recently developed this problem with a 10 year old Worcester Bosch combi boiler. I don’t have a cylinder or any visible pumps or valves. Presumably then it’s something within the boiler not working as it should, or did previously. Any views or advice before I call out my boiler servicing engineer would be welcome. Thank you.
Even with the rads all tee'd before the primary return is there still not the chance of the water working back some, or would there be some sort of back pressure preventing it. Would it be reasonable to put a one-way valve in too, above the tee, but before the tank return?
Hi I’ve got a combi boiler Worcester and my bathroom radiator got warm at top but not at bottom, couldn’t understand it, but it happened in our heatwave we had not long ago
Excellent Roger👍
I have a problem! In in a flat and everytime next door turns on their radiators all mine come on! Even though all my radiators are switched off manually they are all on the snowflake setting ❄ it gets massively hot in my apartment I cannot even cope with the heat all the time. How does this happen please?
Of course that's what it is! Christ on a bike I've been addled about this problem for three years. Even thought about emailing you about it for your Q&A. Right, I'm all over that this weekend. I think the none return valve will be the solution.
Just check the flow and returns on a radiator to see if they run the opposite way.
What about bypassed towel radiators? Have come across this when towel radiator heats both on Hot Water and Central Heating. Is that still an acceptable installation technique?
Yes that summer operation of a towel rail is still common on stored water systems. It is hard to achieve with a combi so an electric element is placed in the towel rail.
Thanks, Roger. Indeed very useful information. Continue to keep up the good work
Thanks for your video, which is helpful. I have a combit bolier, I can't turn off one of radiators. Could I ask what could be the cause of the problem? Many thanks.
Well explained mate! Nice to refresh on these sort of things when you haven’t been jobbing for a while!
I had the opposite happen wherby the rads stopped getting heat when the heating was on.The motorised valve motor was also making a buzzing noise.I replaced it and wired it in correctly and all was good.The only faff is part draining the system first and then bleeding an rebalancing afterwards.Changing the valve took about an hour all in with wiring but overall the whole job took about 4 hours.
What would it be if you have a combi boiler/no hot water tank and when the hot what runs, the radiators heat up. I believe my boiler also does not have a 2 port valve which most folk point to. Boiler is a worcester 28i, 8/10 years old
I have water spitting out from the air vent (steam radiator) what can I do in this case?
Thanks roger, you’re such a generous man....👍
That isn't what my wife says.
Skill Builder that’s cause you spend more time with us knowledge-hungry “builders”, roger! Get the white board out and show her in doors how you’re gonna spend more time with her, starting with a little trip to brighton 😎
Hi Roger, thanks so much. Our radiators do this but they get absolutely boiling hot in the summer not just warm, would it be the same issue ? It’s a new renovation so all pipework is new. I’ve had the plumber look at it but he couldn’t find anything wrong. Split system our underfloor heating downstairs is fine but all radiators on the 2nd thermostat system do it.
Most likely this will be the case but you need to check by feeling the pipework and seeing which way the water runs.
Hello Roger, I am Italian living in the UK and I am trying to get some understanding since I bought a house and had heating issues. I got a code on my Ideal boiler FA which is flow and return reversed. One engineer changed the pump abd the motor in the valve as radiators were hot on hot water only, nothing sorted. After him another changed all the 3 port valve showing me the dirt and the mechanism not working, it looks like I am not having warm radiators anymore(it's been just yesterday he fixed those) but FA code still flashing when on hot water only.At this stage don't really know what it could be :( causing it. When the FA goes on in the cylinder area pump/noise is on, it appears sometimes the C in blu and then fails again. If it wasn't for that FA the system looks like it's working fine...HELP PLEASE
Roger, the reverse circulation happens not to my radiators but to my taps. When I turn my water off at stop tap under sink, the cold water flows out then hot water continues to follow it out my hot water cylinder out of my tap??? The flow doesn't really stop. I had my boiler relocated last year and before this it never did it. When you turn the stop tap off and open a downstairs tap cold water should flow then stop. Can you help with this?
Would it not also be possible to fit another motorised valve to close off the Central Heating Return flow pipes when the Hot Water Cylinder is calling for heat.
We should also explain that in some properties the bathroom rad or towel rail has been purposely put on a separate circuit so as this can be used at the same time as the hot water is running on its own simply to warm or dry towels.
That is the next video.
@@SkillBuilder ,thanks brilliant videos,love them all..i enjoyed the rendering one it gave me the confidence to have a go.
Hi Rodger
Great informative video as always. I also have this issue but with my combi boiler which was only installed a year ago is there any different issues with this or is it a case where as you mentioned they have joined the return in a similar place ?
Thanks
Clem
It won't be this issue with your combi. Does it happen when you are running the hot tap or after the hot tap is turned off?
Skill Builder when I’m running the hot water
@@SkillBuilder it is most likely a problem with your combi boiler. The boiler has a diverted valve also which can get jammed between heating and hot water.
Also your plate heat exchanger could be full of debris/sludge forcing water down your heating circuit.
Great piece of advice Roger! Appreciated. Cheers.
Learnt something new! My only protest is the non return valve. This will cause problems when we do powerflush of the system and alternate the direction of flow left and right. It's obviously not going to allow that. There must be another way without requiring non return valves.
Roger please help… my combi boiler is Set off at the thermostat, (8degrees) yet the flow temperature of the boiler when it drops below 30c kicks the boiler in every 10 mins to keep it above 30c… the wireless thermostat doesn’t seem to be controlling the boiler maybe? Could it be the thermostat or the wireless receiver that is wired in to the boiler maybe?
Any help would be appreciated my bills have just gone up to £400 a month.
Thanks in advance Sean
Although an excellent video explaining reverse circulation, the critical question to ask the customer is “has this problem always occurred or is it a new phenomenon”. Reverse circulation is caused by poor system design and won’t just happen all of a sudden! If rads are getting hot with just a H/W demand is a new problem it’s more than likely Motorised valve letting by. Some valves are more notorious for this than others!!
Top marks for the explanation of the common return though 👍
you are so right. I know some people put up with this problem for years and some discover it when moving in to a new property but a few questions will lead you there faster.
Aaah. So this happened after we got someone to replace the TF1 filter. Could he have fitted it in wrong?
Excellent explanation! thank you
Thanks for this video, I have been wondering why this has been happening in my house for the 7 years I've lived here. I assumed it was whoever did the plumbing being lazy/ignorant and now I know that is more than likely the case.
Just carry out the tests before you start any work, that way you will be sure.