Why Are Your Radiators Getting Hot When the Heating Is Off?

hello i'm roger bisbee from skill builder welcome back to another know your house episode where i'm going to explain a little bit more about uh central heating systems and in actual fact in this one i'm just going to deal with something specific which is radiators getting hot in the summer when you've only got the hot water on so there's a very simple explanation for this a lot of plumbers get this wrong i've been out to many jobs where they say oh i called in a plumber he replaced the motorized valve didn't do a thing charged me 300 quid and went away i'm not saying all plumbers but some plumbers sometimes it's diys having a go sometimes it's electricians but what they suspect is the motorized valve of letting by so i'll just do my little drawing and and then i'll explain what i mean so what we have here is a boiler a cylinder an airing cupboard with a motorized valve in it in this case it's a system boiler so we've got our pump is in the boiler and it's pumping all around you could have the pump in this position here in the air and cupboard but whatever you do basically you've got the hot water flowing out of the boiler into the motorized valve now the motorized valve is where it splits up to go through to the radiators the central heating or it goes through to the cylinder for the hot water and that water inside the cylinder is in a coil so it's not mixed with the tap water and it goes through the coil which transfers the heat to the water which comes out your taps and then it makes its way back to the boiler which i haven't joined up at this moment because i want to explain something about that so in the in the winter when you've got the cylinder calling for heat and you've got a room thermostat somewhere that is also calling for heat it will tell the motorized valve to open up and it will allow water to go down into the radiators and circulate its way back to the boiler it will also allow water to go through to the cylinder until the point where the cylinder is satisfied in other words it's reached its full temperature nobody's having a bath nobody's having a shower so it will turn that circuit off and just leave the central heating running so that's a fully automatic process that will turn on and off if you have a bath that will turn back on open that valve up you'll get a little bit of water going down through the cylinder there heat the cylinder back up again and everything in the garden is lovely until it comes to the spring when it comes to the spring you don't want the radiators on anymore so the thermostat or the programmer or whatever you've got will say okay turn the radiators off and we'll just concentrate on having the hot water on and then you find that when the hot water is running these radiators are warming up they may not be getting fully hot they may just be warming up a little bit but they're warming up so the plumber comes along as i said and he changes the motorized valve because he said that's the culprit what's happening is it's creeping by there it's going through the radiators and it's warming them up and that may be happening that can happen but a lot more likely and the thing that they should actually be proving is that we've got something called reverse circulation now if we got reverse circulation you'll know this because you can feel the flow and return on the system you can turn the central heating on and the hot water on and you can just go and hold the pipes and find out which one gets hot which one gets hot second so in other words which is the hottest pipe there and you'll know which way the water is running through the radiators not always coming through the thermostatic valve the same way sometimes it goes backwards through the thermostatic valve but by holding the two pipes you will soon find out which way the water's running through the radiators now it should be running through the radiators this way in other words up through the flow and then down through the return and back to the boiler so the next thing you need to do is turn off the radiators turn them off at the programmer or the thermostat and the room thermostat and then just allow the cylinder to get hot then you go back and you feel these radiators again you know that they were getting warm before and you feel them again and if you find that this pipe is then getting hot first rather than this pipe in other words the opposite way around to the way it was so you feel them and if you find that that's happening you know that what's happening is you've got reverse circulation you've got water running along here warm water running along here up the pipe through there and back down now the reason that's happening is because a lazy plumber or an ignorant plumber or whatever or a diyer has taken that return from the cylinder and they thought oh look this is the return from the boiler sorry this is a return from the the radiators it's going back to the boiler anyway i might as well hitch a ride on it so they do their tea in that piece of pipe work there rather than in what we call the primary flow and return so if they do that what then happens is that that water can now circulate through the radiators the wrong way so in other words that water that's coming out of there that should be making its way back along there to there suddenly has another route to take it's not all going to take a lot of it's going to find its way back there but a bit of it might start creeping around there and if it creeps around there it goes through there backwards that way round rather than the other way and of course it comes out through there and it goes down through there and it goes down through the pipework and then up and then makes its way back up the system and into the return so that it's going back there but what you've got is that creeping water going around the system so the way to solve that once you've identified that as the problem the way to solve that is to take that return off there and do what the plumber should have done in the first place which is to obey the rule and the rule is that that goes in there the rule is that all returns from radiator circuits whether you've got one two three or four well if you've got one it's not a problem but if you've got several circuits in the house and they're all coming back they must all be teed together they must all be joined to a common pipe before the return to the cylinder is joined so if that's done there is now no way that that return from that cylinder can go down the wrong way through that pipe because if it's pushing there it's pushing there it's only going to meet a dead head there so it can't happen because this is all at exactly the same pressure it's at rest so if you can do that you can change that piece of pipe work around and stab it into the boiler after that tea then that is the problem solved no need to change the motorized valve or anything else if you can't do that and i did come across this a couple of years ago when i went round and identified the problem and then the only way to solve it was to be hacking up her tiles on the on the bathroom floor ceramic tails on the bathroom floor or even a wood floor in the hallway and they didn't want me to touch that understandably so i said okay the other way that i can do it is we leave this pipe here as it was connected there we forget this that's not done we're not doing that so what i said to them is what i can do here is i can put you in a non-return valve so that when the system is trying to go the wrong way we put a valve in it that actually stops the water from flowing the wrong way up the return pipe so we put in a valve so that it just wants to go that way and up there and not down there sometimes you've got to put in a non-return valve in a different position down there or whatever but the idea is that you just stop the water from going the wrong way around the system i did this and it worked perfectly well the only trouble is that when they switched the central heating on and the hot water on they said to me that they were being woken up in the morning by a chattering sound and that was the non-return valve with a little spring in it and it was causing the thing to chatter first thing in the morning as it started up so what i had to do then is i had to put a small ball of fix valve in there onto that system drain it down again put the baller fix valve onto it and then adjust that so i could adjust the flow rate going through that pipe and it just quietened it down enough i could just tweak it and adjust it so that that pipe so that that valve fell silent but it can be a bit of a problem so the best way to solve it if you possibly can is do this bit of pipe work here hopefully not too onerous but you can never tell and if you do that follow that golden rule all returns from the radiators must be twinned together before the return from the cylinder joins the primary return back to the boiler so that's the common return back to the boiler what we call the primary and that way round you won't get any problem i hope you understood that i hope you've followed it i've had a couple of goes that trying to explain it and deleted those so hopefully this is third time lucky and if you've got any questions put them in the bottom below but hopefully that solved a little problem that may have been bugging some of you i know there'd be somebody coming on the comments going ah that's my problem i know how to solve it take care don't forget to drain the system down turn off the water and know where to turn the water off that's a very very useful thing for anybody in any household flat to know where to turn that water off in an emergency i'm roger bisbee don't forget to [Music] subscribe [Music] [Music] you

Channel: Skill Builder

Views: 165,745

Keywords: radiators getting hot when heating is turned off, radiators getting hot when running hot water, radiators getting hot when water is on, radiators getting hot when heating off, radiators getting hot when heating not on, radiators getting hot when only hot water is on, Why Are My Radiators Getting Hot, radiators explained, central heating, fix radiator, central heating system, central heating heatwave

Id: vu55TgMMDyE

Length: 11min 16sec (676 seconds)

Published: Sat Sep 05 2020