Gas Training - How To Test A Boiler Thermistor - Ideal Boilers Engineer

gas training testing a thermistor on a boiler my name is alan hart and in today's video we've got his friendly ideal boilers service engineer back and he's going to show us how to test for misters in in a boiler what he's going to do to start we're going to have a little talk about thermistors and then he's going to and then he's going to um test them with multimeter show you how to test them show you how um putting clamps on with temperature probes and stuff like that so it's a really really interesting video um yeah if you've got any videos that you want to send in if you can send them in on landscape like that if possible so when you video like that and it just makes the editing better and i will add my whatsapp details below for them also if you want to send a review or if you want to promote your business or anything like that if you're a gas engineer or a plumber if you do good work then get in touch i'm happy to help you um i've done some videos with some other people and they managed to get quite a bit of work from doing the videos so anything we can do really to promote good work in industry if we promote good work then obviously the people that are watching this channel as well will see that work and then hopefully they will also then try and do a better job as well and i'm not saying i'm not you know i'm not saying that i'm perfect but what i am saying is that i'm always trying every day to be better than what i want yesterday um so yeah anyway let's get over to ideal the ideal boilers engineer and look at these feminists and please if you could please put a thumbs up on the video and also add a comment below thank you hello youtube i'm back with another video uh and today we're going to talk about femistas or the proper name which is a thermostat resistor or even an ntc sensor which is a which means negative temperature coefficient which which again means that the measurements or the readings move in opposite directions as the temperature within the heated circuit rises the resistance within the thermistor itself decreases and the circuit board will see a drop in voltage that's uh 99 percent of how thermistors work there are well they will maybe there used to be ptc thermistors which is positive temperature coefficient which obviously the readings move in the the the same direction negative temperature is the one that i think almost all manufacturers use nowadays and uh i mean i could be wrong but i don't think anyone uses ptc anymore so they're basically just an instrument to measure the temperature and relay that information to the circuit board now you can get faults with thermistors they can be out of calibration normally at the high or the low end of the thermistor and the fault will generally you know show up as a a temperature problem within your boiler even you know the boilers running a minimum fire at a low temperature or um it may not even fire at all it could be holding it off the the fermenter is completely gone um and the circle board is looking for the thermistor before it fires and if it can't see it it'll just hold off ignition so um that's another a problem that you can have with misters generally they're quite reliable but i'm going to show you today how you would test and check a thermistor again on my boiler at home the ideal logic we have a return for mr and we have a flow for mr back there that flow for mister it's not just a float for mistletoe it was originally used as a no flow for mr which we use as our um pump proving switch or differential pressure switch we don't have uh a switch a lot like the valence and what have you they have a pressure switch that detects the pump movement that's our flow from mr that one there what we do with that we give the boiler about 10 seconds to detect the movement in temperature from that thermistor if it doesn't detect it it'll shut the boiler down and that just proves that our pump is running it's also an overheat thermistor which will cut off the border around i think about 105 degrees but generally all thermistors no matter what manufacturer it could be what's the violent basement boxing i think the the measurements the readings the conversion table are all around about 10 kilo ohms at 25 degrees i could be wrong other manufacturers may have slight variations in their conversion but and probably worth checking before you you do this but uh i'm quite positive that all for mrs work on the same conversion table so what i'll do i will set up my testing area and we'll crack on and i'll show you what to do right i'm set up now um what i've done um i've put a my temperature clamp from my analyzer i've got my analyzer set to temperature as you can see there it's reading 46 degrees on my return pipe and my temperature clamp is literally clamped right next to my return from mr you can't really see that very well but you've got to get your temperature clamp as close as possible to your thermistor you're testing it's almost literally next to it and i have my multimeter set to ohms we're testing the resistance through the thermistor and as you can see there my multimeter is registered in 3.8 kilo ohms now all thermistors are measured in kilo ohms if you're getting a reading of let's say 100 ohms or mega ohms your thermistor is gone so straight away if you look for the k if you haven't got the k there maybe you've not got a good connection on you for mister or you for mrs out of calibration if it's saying anything anything else other than k you for mrs probably had it we're reading three point a 3.8 kilo ohms there so what i would then do i would refer refer to my for mr char and if we look there it's not going to be exact but um 3.7 to 3.8 is roughly between 49 and 48 degrees we got 46. so it's within the range you've got a you've got about a 10 um range so you're from you're not going to get the exact reading whatever that says on your chat to read what your multimeter is reading and how you would test this you would kill the power to the boiler you would make sure it's dead do your isolation test you would find the connection of the pcb board and disconnect the connection off the pcb board however and then you put your multimeter connections in there however for this purpose i have made up my own test lead just to make it a bit simpler because it's hard for me to hold my probes um onto that connection there and hold the camera at the same time so i mean this is probably a good thing to show you actually um what i've done when i've changed wiring harnesses i'll just my leads are in there a little terminal block there what i've done i'll pull them out and i'll pull off this lead what i've done in the past if i've changed wiring harnesses on boilers and um you know because they're faulty i've snipped off the thermistor leads so as you can see there the yellow one with the black that's for a wet pocket for mr that's for a clamp on drive for mr that's also for the old ice size what i've done i've just put them in a sleeve and connected them to a bit of terminal block and i've clamped down the terminal block just enough so but my leads will actually hold in there but normally what you would do you would test it here you'd put your your your probes within these connections because not only are you testing the thermistor you're also testing the wiring harness as well because you may not have a problem with the thermistor you may have a problem with your harness so the best way to test the thermistor is to do it via this harness disconnect it from the circuit board put your probes inside these connections and the black and pink and the black and red correlate to the black and red is the return from mister the black and pink is the uh red thermistor so that's how you check a feminist you've got to be within a 10 range roughly if you're not then it's probably worth swapping over mr um whilst i'm talking about this lead that i've made i probably should mention um this wasn't my idea this is not my baby i actually saw this on another youtube channel um the name's heating geek he's a really good diagnostic engineer i must watch one of his videos and he did something very similar to this in this video and i just thought to myself that's genius if you wanted just to test the thermistor quickly rather than open a circuit board disconnecting the cables if you just wanted a quick measurement rather than opening all this if you if you change if you're changing a boiler you've uh if you're taking an old boiler out you can snip off the domestic cables it's well worth doing if you if your test ball is a lot so he give me that idea if you're not subscribed to his channel it's probably a good idea that you are because he gives out very good uh information and he's very knowledgeable so yeah i mean that's it really that's how you test it for mr it's as simple as that and i hope it helps until the next one sayonara this is a little bonus tip for you after that little tip i gave you with the thermistor lead i thought i'd share this before i go um i think we've all been in a situation where we've come to do a combustion analyst analysis on our boiler the flu is sideways on the ball is in a cupboard or against the wall and you just there's no way at all you can get your probe into that flue there just because it's too long other than having one of the small little probes you're going to come up against a little problem i've devised a little way to get around this and i thought i'd share it with you so what i would do i would remove this test plug here pop it down there and i have made myself a little adapter basically all it is it's the same as one of these i've put a hole in it and i have used the test point off an idealizer like i said all boilers can come in handy you can get little little gadgets off them what i'll do then is i would screw that onto the elbow there so now we've got a little test point get myself a little bit of silicone tube from air pressure switches put that on the end and then voila put the other end onto my probe when i've done that i've just increased the size of the tube with a bit of gauge tube so now from there all the way around to there we can now take a reading from our flue sampling point that's just another little tip two and one today now this time i really am going once again thank you very much to the ideal boilers engineer thank you for the time and effort that you put in to try and help on this channel it's um really really appreciated and thank you to everybody who's watched please put a comment below please put a thumbs up really grateful for thumbs up it really helps with the videos and yeah if you've got any suggestions please put them in comments below as well and as i said at the start of the video if you want me to come come out to one of your jobs or if you want to promote your business or anything like that then get in touch i don't want pain for to do this so um i want to try and help i want to try and raise the standards in the industry i think the industry is is lacking and i'll try and break standards and i believe that if we show good work then um we can raise the standards and it's not about shiny pipes either so for me polishing pipes is you know that's not that that's not what it's about it's what's inside the pipes that matter so flushing the system um setting the boilers up correctly installing flues correctly um just all generally um just installing the boilers well and i believe that if we install boilers better then boilers will last longer and also the customers will then still have warranty so the manufacturers cannot get out of warranty so things like checking with the checking with area pro check afterwards things like that i'm taking pictures videoing what you've done so you can prove that when you installed it you installed it correctly and yeah as i said it's just all about trying if possible help rate standards you know as much as we can um help some of the new people into the industry or even people that's been doing it some people's been doing it five ten fifteen years i mean i had somebody over there he'd been a gas engineer for 20 years and he messaged me and just thanked me for all time and effort that i've put into doing these videos he said it's really helped him and and i think that as an industry a lot of us work by yourself and it's quite a lonely place when you work by yourself um so yeah you know let's build this community let's help each other help the charity as well also you know we made that i've got nothing to hide you know i want to build this channel so i want it to help me as well but i wanted to help me i wanted to help you i wanted to help the charity and i just want it to be a um just a good thing that we're doing really so yeah and i'm definitely babbling on now um thanks very much thanks for watching

Channel: Allen Hart

Views: 20,347

Keywords: combi boiler thermistor, gas training, plumber, How To Test A Boiler Thermistor, fault finding, boiler repair, combi boiler sensor, boiler fault finding, how to fix boilers, boiler repair videos

Id: ZufNxePN_zg

Length: 16min 35sec (995 seconds)

Published: Wed Feb 17 2021