Why Is My Boiler Running When It Should Be OFF, Is It Normal Or Is It Faulty?

hello is your bullet staying on when it should be off so you've switched off your hot water you switched off your central heating and yet the bullet is still coming on well in this video I'm going to go through the reasons why your bullet may be running when it should be off and also some comment and not so common folks which I regularly come across which may be bringing your boiler on when it should be off right let's get straight on with it now there are several reasons why your heats only boiler or combination boiler may be Stadium running when the timer says it should be off now the first reason I don't get asked about very often but it does crop up and that's when the hot water or the central heating turn off people sometimes hear the boiler continue and run it with a pump running for some time after the boiler should be turned off now this is perfectly normal and it's the pump that you were here running and it will continue to run for about five minutes after the timer has turned off and that's just to pump the remaining heat out of the boiler which is going to keep it a little bit more efficient and it'll also stop the boiler from overheating and it will continue to around it for about five minutes after your timer all your hot water has been turned off now the second reason your boiler may be running which is perfectly normal is from frost thermostats again it doesn't matter whether you've got a combination boiler or a heat only boiler if your boiler is installed in a garage in an outhouse in a loft anywhere where it gets really cold there's a good chance that your board has a frost thermostat inside it and when it detects it it's getting very cold it's going to turn your boiler on now typically if your boiler has a frost thermostat right about eight degrees the ball is going to bring the pump on and that's just going to pump water around your system and around the boiler to try and warm it up if the boiler starts getting colder again and it recognizes getting down to maybe five degrees the ball is then going to bring a burner on and it's going to start heating itself up to keep itself warm and stop it from freezing so if you're finding that you're waking up in the middle of night and your central heating is running or maybe it's running during the daytime and the weather is really cold outside so you know Dances minus temperatures then it's probably your Frost thermostat in the boiler which is kicking in and it's keeping it boiler hot and stopping it from freezing and there's not a lot you can do about that it's just going to keep on running whilst it is really cold now as well as Frost protection inside boilers we can also get Frost protection which goes onto pipes and frost protection to protect areas so if you've got pipe work or maybe hot water tank up being Loft anywhere where it's really cold there's a good chance you can have some Frost protection and when that gets cold it's going to bring on the boiler now the difference with these devices is they are not going to run the pump first they're going to bring the baller straight on so the ball is going to start heating straight away with pipe protection hopefully your pipe's going to warm up fairly quickly and it'll then turn the boiler off again now if you have area protection where you have a frost thermostat on the wall then as soon as the temperature drops and the frost thermostat detects that it's going to bring a heating all your hot water on to warm that area up now if that area stays cold continuously for a long time it's just going Gonna Keep On Running and it's not going to turn off that heating or the hot water until the area warms up and that Frost thermostat turns off now like I said there's not a lot you can do about this if your Frost protection is in your boiler then that's preset and there's nothing you can do about that if you have pipe protection or area protection you could check to see what they're set at and maybe adjust those down a little bit if you're trying to reduce the gas bit and stop your boiler from running the only other thing you could do is actually turn your boiler off and obviously then you're risking something freezing and then getting thousands of pounds worth of water damage so that's not what I would recommend so that's it for the frost protection now let's move on so the rest of this video is going to be for heat only boilers that's where you have that large hot water tank and not combination boilers if you do have a combination bullet then I've made a completely separate video All About The Faults which you may find on your combination boiler which are keeping it running when it should be off and you can find that video in the cards above now or down in the description so whilst giving you heat any boiler running when it should be off so we are now looking for a fault on our system which means we're going to have to start taking things apart if you don't want to take things apart then call a good engineer to come and take a look at your system so there's our programmer our boiler our mid position for our zone valves cylinder thermostat room thermostat Wireless room thermostat and of course the wearing Center any of those could be given us a fault because these modern systems can be incredibly complicated and even after 30 years experience I'm still left sometimes at scratching my head trying to work out what on Earth is going on the next part this video is a little story I made of me going to a property where the boiler was coming on when it should be off and it was causing the boiler to overheat if you do want to watch that you want to skip straight to the folk diagnosis just jump to the next chapter just before that I quickly let you know that I make lots of videos to help you with your heating and one of those is 10 ways to reduce your gas bill if you want to watch that video you can click on the cards but now or you'll find it in the description below so now let's find out where our ball is staying on when it should be off so here's the glow on boiler and it was tripping out with a F5 volt which is overheating now it turns out it had nothing to do with the boiler so the boiler was working absolutely fine and wants to fix the fault the boiler continued to work perfectly okay so let's go upstairs to a cupboard on a landing where the hot water tank is and the controls and that's where the fault actually is now as soon as I go into the air and cupboard I noticed that there are some watermarks here there's a brown rust marks which have been dripping from this device up here if you want to know more about what this device is and how you can stop it from leaking then I made a completely separate video about that and you can find that in the cards above now or down in the description now although it was a leak that was causing a problem it wasn't this device that was causing problem it is this one down here now this is an automatic bypass valve and you can see it actually has drips of water on it right now they've actually got a jug down here which is catching the water so I can clearly see that this valve has been leaking for some time now what's been happening is the water has been dripping out of this valve and it's been dripping directly onto this electrical plug right here and this electrical plug controls the zone valve right there and here's the other end of the plug which has been connected onto the zone valve you can see the water rust lines have been going across all the terminals causing a short circuit and it's amazing it didn't have a fuse blow or have the house electrics keep tripping out but that's probably because there's no earthworm on this zone valve now the brand and blue wire operate the motor in the zone valve and the gray and orange words switch the boiler on and off now a note for the engineers here it's worth knowing that some Modern boilers only need a tiny amount of voltage on the switch wire to actually bring the boiler on so there was less than 50 volts seeping across these terminals at an extreme me low amperage but that was enough voltage on the switch wire to tell the boiler to come on so although both Zone files were closed the switch well was then being told to come on the boiler would start up there was nowhere for the water to go and so the boiler overheated and tripped out now before someone shouts that's what the bypass valve is for the bypass valve is there to let the water continue to circulate once both the zone valves have closed and the boiler has turned the flame off so the water can continue to circulate around the boiler dissipating the heat from the main heat exchanger after the central heating and hot water zone valves have closed if the boiler fires up when both these zone valves are closed there's just not enough flow through the auto bypass and a boiler is most likely going to overheat as this one has now my job today is to replace this automatic bypass replace this electrical plug because it's not worth trying to save that and I'm gonna also replace this auto air vent thing on the top here with a 28 millimeter Magna clean so over here I've got all the parts to replace that so I've got my 28 millimeter Magna clean I've got my electrical plug and then there's also the automatic bypass now this is a pressurized system so all I need to do is to drop the pressure on the system I should then only need to drain the Waterway from this little part of the circuit because I can isolate the pump valve and of course at both the zone valves are closed again isolating this small part of the circuit so now I've replaced that auto air bent thing I replaced the electrical plug and also the auto bypass so here's the new automatic bypass and then here's the electrical plug and just tuck that out the way there just in case the auto bypass decides to start dripping again in the future and of course I've also installed the 28 millimeter ad Magna clean professional too I'm going to top this system up to around about one bar I can let the air rates from the bleed point on top of the magnet clean and there we go it's all topped up now now we'll need to do is just run the boiler and make sure it's all running fine now I thought I'd just add that when I first came to the property I turned the power off and on and I noticed straight away as soon as I turn the power on the boiler fired up and of course it wasn't cooling for heat so the central heating and the hot water weren't turned on and yet the boiler was firing up so I knew something weird was going on and probably what to do with the controls now normally in that scenario I would then test the switch live on the boiler to see if there was any power on it but a quick look in the Airing covers obviously soon revealed what the fault was so now I can just push the button here to bring on our Central Heating and hot water upstairs a little more bleeding off the Magna clean and there we go that's all full of water I know the hot water valve is open because this lever is all nice and loose the pump is set to its full power so I can see the lever is right around on number three and there we go it's now all up and running now just so you know if you've got a faulty zone valve or mid position valve and you want to open it up and keep it open then you can move this little lever on the end here and then clip it into the little clip and that will hold it open and I can do the same with this zone valve down here as well and that keeps both the circuits open which can help me when I'm bleeding the system before we get onto those folks let me quickly introduce myself my name is Mark ballad and I've been a gas registered engineer for nearly 30 years the Ami channel is to help you with your central heating and your plumbing if you find this video helpful at all then please give me that little bit of feedback by clicking on that thumbs up and that will also help others to find the video you can click on that subscribe if you like the video click on the Bell if you want to receive a notification and of course share the video with your friends a big thank you to everyone who has thanked me by getting me a cup of coffee and leaving a donation in my toolbox phone it is really appreciated and it does really help me to make more videos which will hopefully help you oh and don't forget to check out my website where I've categorized all my videos and I've left links to all the products and parts that I recommend end so find the way our boiler is staying on is a process of elimination it's more likely to be a controls electrical fault so here's my heat only boiler and it's a valiant Ecotec plus 418 so the first thing I would want to do is to find out whether it's the boiler which is at fault or if it's one of the other controls which are at fault now I could do this from the boiler or I could do it from the wireless center all modern boilers have a printed circuit boards inside them and it could just as easily be the circuit board which has gone faulty but before I go diving into the wiring center I'm most likely going to check all the controls and make sure that they're all working correctly so I'll turn on the hot water and just make sure that the zone valve opens up if it's a zone valve or if it's a mid position valve it stays in a hot water position and let the boiler fires up and when I turn it off the boiler shuts down again and the hot water zone valve closes again and the mid position valve would stay exactly where it was then I do it exactly the same with central heating I turned that on the zone valve should open up if it's using 0 valves or if you have the mid position if I have the valve should move all the way across into the central heating position now not every valve head looks like this one which is nice and easy to see what is going on I would then turn the hot water on with the central heating and then the mid position forever should move into the mid position that is providing the hot water cylinder stat is calling for heat I would also check this cylinder thermostat by turning the temperature up and down and making sure again it switches everything on and off as it should do I'd also check the room thermostat but that is less likely to to be making your boiled stay on now if you have wireless controls like this Honeywell t3r then you want to make sure that that is working properly and that the receiver box is turning on and off correctly because sometimes I've seen the green light turn all off on the relay box but the switching relay inside the box has become stuck and it sticks in either permanent on or permanent off if that happens there's nothing you can do apart from replace the unit if everything is clearly operating correctly I'm then going to go into the wiring center now just a quick disclaimer I've got to tell you that you are working with two 30 volts and this can kill you unless you are an experienced engineer or electrician I suggest you do not go delving into your wiring center so here's an old Warrior sensor which I cut out of a system and I just got on my desk here so I can show you what's going on so the wires coming in here we have that room thermostat that's wide in there there's the pump that's word in then we've got the live neutral and Earth obviously they Supply Power and then we've got the mid position valve that's wired in there and then we've got the programmer and then this is the boiler wire now this is the one which we're interested in so I've left that one loose and then on the end here we have the cylinder stats now this is a worry diagram which I made many many years ago and if you want a copy of it you can download it from my website it's what's known as a white plant so it has a programmer a mid position valve a room thermostat a cylinder thermostat and the boiler that controls the pump on the boiler here we now have a permanent live so we've got permanent live coming down to the boiler we've got the permanent neutral and the permanent Earth obviously so those wires are always connected to the boiler now not every bullet will be wired in the same but in general this is the way a lot of boilers are now wired in and then we have two extra wires here going down to the boiler so we have our gray wire here so that is our switch wire so that would be switch live and on the boiler it'll be labeled as L for switch live and this wire turns the boiler on and off then over here we have our pump live now to be labeled as PL on a boiler and you see that where it comes across and it goes into our pump Live Wire so it's the bullet that the sides when to turn the pump on and when to turn the pump off obviously always check your boiler manufacturer instructions to check the wiring of your boiler is correct now if this is looking really complicated then that's because it is even with 30 years experience I'm still left sometimes scratching my head trying to work out why a system will not work correctly wiring sensors can be a right mess making a nightmare to know what's going on so I highly recommend that you do call a professional now the wire that we are interested in is this gray right here this switch Live Wire what I then normally do is I take my multimeter just here I would set it to AC for 230 results in this case it's 750 and then I would take my probes and I would check what voltage I have got now see this is not live so I'm not going to have any voltages at all but I will take my two probes and I put the neutral into the neutral so all these terminals just here are on neutral obviously the ones which are blue so I put that into there and then I will check to see what voltage I've got on the switch Live Wire now like I said I'm not going to have any voltage because it's not wired in with the hot water and central heating turned off I'll check the voltage if it's 230 volts then it means that something else is turning on so it may be that the programmer is faulty then I go back through and check on the other wires so number nine in this case it would be to check if your central heating is on so let's see if I've got two 30 volts on there and I'd also check to see if I got 230 volts on the other connections also one of the hot water ones will always have 230 volts on it now sometimes I'll come across it where the program has actually become faulty and although the programmat says it is off I still have 230 volts on that central heating wire and of course that would keep the boiler on an easy check for this is just to remove the programmer and see if the boiler turns off now this programmer is nice and easy to remove just a couple of screws and it just hinges it off but unfortunately not every programmer is as easy as this one with the power still on these will be 230 volt live terminals so be careful if your water switches off as soon as you move the programmer then it's most likely going to be the programmer that is faulty but that is not a guarantee and I would do additional checks to ensure it was that causing the problem go back to my switch wire so I'm going to test this wire here and see what voltage is on it and obviously when everything's off there should be no voltage at all so when you turn your hot water or Central Heating on we should get 230 volts coming down this orange wire which is coming from the mid position valve valve and it comes across and then comes down obviously into that switch wire on the boiler now on the very odd occasion I sometimes find there is a little voltage here so somewhere seeping through the wiring there is somewhere between 0 and 50 volts on the boiler switch wire here and that may be enough voltage to actually bring the boiler on because the circuit board on the boiler is detecting that tiny voltage now typically what I would do is I would come to this switch wire here so when the boiler is running and when it should be turned off I would then disconnect this wire and see what happens so I'll take my screwdriver put it into here undo this screw and then pull this lead out and see if the Border stops running so you take the switch wire out so that's now disconnected the switch wire then the boiler should shut down now if the bullet stays running with the burner still on and heating then it's more likely to be the circuit board on a boiler which is at fault or it could be that the boiler is actually wide in incorrectly I never rule anything out I could then put the switch wire back into its terminal and see if the boiler comes back on again and if it does I then probably do this a couple more times just to check that is definitely this which is bringing the boiler on now I have found a particular scenario where at certain times this low voltage is a problem and it brings the boiler on now the particular scenario which I'm talking about is where the hot water and central heating have been on and then the hot water goes off leaving the central heating on and then when the central heating goes off the boiler stays running and then the only way to stop the bullet from running would be to turn the power off but with the same system if the hot water is running at the same time as the central heating and then they both go off together this problem doesn't occur and the bullet doesn't stay running now this low voltage seems to be coming from the mid position valve because inside there there is a small circuit board and when the central heating is the last thing running and the timer then turns the central heating off the valve will stay in that central heating position and then on the very odd occasion a small voltage seems to seep through and that can sometimes bring the boiler on so you could then change your motorized valve or motorized valve head costing around 70 pounds or more and hopefully that would then stop the boiler from running when everything is then turned off now there is another option where we can just fit a little capacitor across these Terminals and that will remove the voltage and stop the boiler from staying on now this is a 0.47 UF suppression capacitor and this is what I use and it removes that small voltage and stops your boiler from staying on and costing only around seven pounds it's definitely the much cheaper option and all we do is wire this ink so it goes from our switch Live Wire to neutral and it's as simple as that and here it is again on our electrical drawing now we can go through that same check again leaving our central heating on last before it gets turned off and you could check across that terminal now and see if you still have that voltage but more importantly has your boy let's stopped staying on hopefully it has and you no longer have that problem if you're a heating engineer or an electrician and you've seen these capacitors in their warrant sensors and you're not sure what they've been for hopefully this video has helped you out and has given you that little bit more knowledge because I have found that this fault is not well publicized and I find it is very difficult to find anything information on this last fault so I hope my video has helped you out I'm afraid I'm not able to go through each individual item explaining how I would diagnose the fault because that just comes down to experience and a good understanding I just wanted to say again that the wiring and fault finding on Modern systems can be extremely complicated and finding folks can be a real nightmare so I strongly recommend that you call an heating engineer or gas registered engineer to come and take a look at your boiler if it's continuing to run when it should be off so that's about it then so if you want to watch my video on 10 ways to reduce your gas bill you can click on the video just here and of course you can click on subscribe you can click on the Bell give me a thumbs up share it with your friends and as always my toolbox friend bye for now and I'll see you next time

Channel: Mark Ballard LTD

Views: 19,262

Keywords: boiler running when switched off, why does my boiler keep turning on and off, why does my boiler keep turning on by itself, why does my combi boiler keep firing up when heating is off, why does my boiler fire up in the night, boiler frost protection, boiler frost protection on all night, what temperature for frost protection, central heating frost protection temperature, why is my boiler coming on when it shouldn't, why is my combi boiler running when nothing is on

Id: DI2t99hJLCc

Length: 22min 28sec (1348 seconds)

Published: Fri Jan 20 2023