This has just saved me money, time and hassle. If a thermocouple only produces millivolts, that output will suffer from any high resistance. I stripped my Smeg hob down and, sure enough, the non-staying-lit burner had a bit of corrosion. Everything cleaned, rebuilt and all OK. No cost at all. Thanks.
Thanks for the video. I was having an issue with the pilot light for my RV stove. Before I completely replaced the thermocouple i followed the test progression you described and found that everything seemed to be fine. I reseated all the connections and got it to work. Thanks from a novice electric guy.
Apply the flame longer, after all, the pilot stays lit 24 hours a day. Voltage should rise to 25 to 35 millivolts DC on your DVM Voltmeter. Using that device tester in the video, you still need apply the flame to see that the valve stays open when the button is pressed down.
Big help-my meter measures MV and was really good wondered about the spring but realized there were two springs in my Dual Radiant heater. The test showed it was responding to the MV output. Diagnosed it as a failure of the Dump Switch that failed to connect on two heaters. Was cheap to replace -ordered four to be on the safe side.Now I have three heaters that all work! Good Job
Brilliant thanks mate. I found a gas pizza oven at the dump today and the flame kept going out every time I release the knob. You just explained perfectly what's going on! Cheers
When you press the button down, it bypasses the thermocouple and opens the pilot valve for manual lighting and when it’s heated enough you can release the button and the thermocouple will take over by holding the pilot valve open. The button itself isn’t supposed to stay depressed if the thermocouple is working, but the pilot valve should stay open if it’s sensing the flame properly.
Thanks for the video! I don't care if you call the thermocouple a one-eyed wombat - you helped me fix my heater! You pebble! (Oh, was i supposed to say "ROCK"??)
Danke von Deutschland aus, das war genau das was ich wissen wollte. --> Thank you ! That was exactly what i want to know, now i know that the elektic cycle is going over the copper and the middle Contact of brass ( it seems like brass in my case at home ) . Both are elektrically separated from the sensor to the gas-Switch. Thanks !
It's sometimes not an easy chore at all to adjust a Honeywell thermocouple on an antique gravity furnace like the one that I have, and simply because the thermocouple is not only located on the far side of the burner, it's also difficult to see in there. Actually, the best that I could achieve was 26.9 mVDC on the Honeywell 30.0 mVDC thermocouple, but I suppose it was good enough as it activated the control quick enough.
14 is middle of the road, but not bad. Anything under 7, & you're dead in the water. If it's 14, get some emery cloth & sand the thermopile probe clean. Shut the gas off first! Or you can install a new one. I think they cost about $10.
My Thermo Pile & Thermocouple both test with ample milliamps. When I turn on the heat demand switch the burner does not go on. When activating the heat demand switch, the miliamps do not increase on my tester. Is this because the burner does not go on? Or is my Thermo Pile defective and the cause of the burner not turning on when I turn on the heat demand switch? The pilot light is strong and blue. I have tested the wall switch that should turn the burner and the switch tests good. What else could be causing my burner not to turn on?
I have a thermocouple issue on my furnace right now. I tested the mVolts and it climbs to 29.2mV. From what I've read, 25mV or more is considered good. I cleaned all the connections at the cold end and measure 0 Ohm from copper tube to the gas control's housing. But while heated, it still fails to actuate the plunger. A new thermocouple fixes the issue. So my thought is that open circuit voltage test is not good enough. As my old thermocouple fails while under load(ie connected to the gas control)? I'm reading 0 resistance across the plunger relay which makes sense as a relay. What load resistance would be good to test it with? And what should the current(mA) be when it's under load? I think that will tell us a lot about a TC's real performance as I know they do degrade with use. Of course my gas control is 20+ years old and may just need a peak performing thermocouple to have enough juice to drive the old plunger relay.
If you were to apply a small amount of voltage from a milivolt source to the thermocouple, would it kill the termocouple? Not to the probe but from the connector.
Hey mate, can you help me out here? if my digital thermometer is type K but my thermocouple wire is type J, i know that i will get a reading; however, how accurate is that? Is there any way to apply a correction or something else? because in my experience, by using such a set up im getting a reading with discrepancies up to 2-3°C respect to the reading obtained by using a thermometer type K with a thermocouple K.
I have a 1971 Piper Cherokee 140. Temp gauge stopped reading. I sent the DG (Directional Gyro) off for repair and 50 year old temp gauge. Should test bad I assumed. It tested ok. So the new sensor and cable (4 years?). I assumed I could test the sensors like a resistor. Can put volt meter in windshield. But “sender” has to be bad. Actually, it’s simpler than that.
Steve Trubilla Black lead goes to the copper jacket .... the red lead goes to the lead colored tip, the white lead was just an extension I had on the red lead.
They normally call it a thermister. It’s very similar but instead of making voltage like a thermocouple does a thermister acts as a resistor. As the temperature changes the ohms change and allows the mother board to read the temperature. To test it you use the ohms setting and a lot of times the manufacturer has will tell you what it should read at various temps. A lot of times they advise you to dip the probe into ice water and take an ohm measurement at the wires.
ELECTRIC TECH Yes. I plugged in some lead wires and taped them to the leads of my multimeter looking for voltage change patterns of any kind with no success. I will see if I can get a reading with Ohms. Because this is different than a thermocouple, are there still the concept of 2 dissimilar metals in the wires?
Jesse Levine the wires are probably the same metal one wire carries voltage from the mother board to the temp sensor which restricts the voltage based on temp and the board then reads the returning voltage. A lot of thermisters I deal with are made from ceramic material but it could be anything.
rgee bee Watch the flame 🔥 make sure it’s directly hitting the thermocouple and not moving around from wind / or blower motor, if that looks good your control could possible be going bad
Or, you might have air coming back through your exhaust pipe. In this case, you might want to check your ventilation setup, and take steps to prevent back-flow.
Test voltage. Normal operation is 17-32mV. If lower, check that the pilot flame is burning steady and contacting the tip of the thermocouple. Check venting for obstructions and that the water heater is getting enough combustion air. When the main burner fires, the flame should be more blue than orange. Are you running out of hot water? If you run your tank to depletion (completely cold), the water heater will condensate, and the drips of condensation can put out the pilot flame. Less common is the gas control is at fault. Just some ideas, hopefully it helps!
Guardian TV....Thanks much for suggestion will check it out. My furnace is a wall mounted small unit in a 500 sq ft cottage in Upstate NY, and I've had the place for 15 years....I think the unit was installed in the 80s. This is the first thermocouple I ever replaced.
thanks Pros....It's a wall mounted Sears "furnace" with a blower. I did have a bee hive in an adjacent wall last year and I think I remember moving the flu pipe and reconnecting it.....will ck it out. Also I may not have the pilot flame on the tip of the t-couple.....will ck out and fix. Thanks for suggestions
+wade rigsbee Its great, I use this one to do all my videos because it has the biggest display. I have fluke meters that cost twice as much but this klein Meter has all the same functions and works just as good. The only thing I like better on the fluke meters are the wire leads are better quality, so I end up using the fluke wire leads on my klein meter when I'm working on customers units.
+killer350dz you can find them online, I got mine from one of my distributors a few years ago and only cost like 20 bucks, you can remove them out the valves but they don't have treads on them like the tester does.
Very good and informative video, usually read through the comments cause I often pick up something extra, there are a lot of English proofs having a problem with your pronunciation of thermocouple, seems strange, they are looking for info on testing this thing, trouble shooting requires an analitical mind, yet this becomes a big stumbling block for them, what because of this they get so confused that the knowledge you went to the effort of sharing with a very well done video is some how not good enough, I wonder how man useful videos this group of rocket scientists have produced, jeez some people.
even getting a 30 mv output reading on a thermocouple does not necessarily mean its good. The time it takes to reach the operating voltage is also a factor. My boiler pilot light would not remain lit so I tested it with a meter by removing he end that was connected to the gas valve and used the pilot light to heat the element . It took a long time to get to 30mv. Initially I thought it was good and that the problem might be the gas valve but I chose to replace it anyway and sure enough the one that I tested was bad.
+588158 the fact that it made voltage should hold the coil in place once lit, sometimes just unscrewing / rescrewing the end in and out of the control fixes a contact issue.
I did that too figuring it might be a high resistive connection but it didn't work. The tube was quite sooty which may have acted as an insulator hence the slow rise in voltage.
The thermocouple demonstration is OK. But I am sure that the mV and small current generated by the thermocouple can never drive a solenoid. You must be having another supply which will pump enough current and voltage to drive that solenoid. The thermocouple is only giving a signal. Pl check.
Mack James excellent question lol. Well I found out a few years ago that UA-cam prefers videos that get a lot of comments and when you pronounce something wrong it gets a ton of comments. The hot water heater is just me being retarded. Bout 2 years ago I started saying it correctly “water heater”.
I'm not a plumber or electrician but even I know that's a water heater....NOT a HOT water heater. If you have hot water why heat it...lol. (yeah yeah....I know it's commonly called a hot water heater but that's incorrect).
Dude! You can spell, right? There is no "R" at the end of thermocouple. Thanks for the video but you might want to do it over so you won't give a "wrong" impression. Best of luck.
Joseph Stokes well aware of how to say it but more comments on UA-cam tend to make the video get more views. So by pronouncing something wrong people naturally correct you and it causes the video to get better interaction 😀 and place higher on the search.
It's only understood by people who don't know the meaning of the word thermocouple, which is "a device that consists of the junction of two dissimilar metallic conductors" i.e., a couple of two dissimilar metals. Maybe now you understand why it's thermocouple and not thermocoupler. Another popular error is thermocoupling. If you like thermocoupler, you might also like thermobabble and thermoBS.
This has just saved me money, time and hassle.
If a thermocouple only produces millivolts, that output will suffer from any high resistance.
I stripped my Smeg hob down and, sure enough, the non-staying-lit burner had a bit of corrosion.
Everything cleaned, rebuilt and all OK. No cost at all.
Thanks.
Thanks for the video. I was having an issue with the pilot light for my RV stove. Before I completely replaced the thermocouple i followed the test progression you described and found that everything seemed to be fine. I reseated all the connections and got it to work. Thanks from a novice electric guy.
Mate, this video is so helpful for me diagnosing a faulty thermocouple. Thank you so much.
Apply the flame longer, after all, the pilot stays lit 24 hours a day. Voltage should rise to 25 to 35 millivolts DC on your DVM Voltmeter. Using that device tester in the video, you still need apply the flame to see that the valve stays open when the button is pressed down.
That's good info. Thanks.
Way better info than the video to much talking about other stuff
Surprise he failed to mention it
Very clear and concise explanation and it will be very interesting to compare the readings from a new unit with the presumed ''duff'' one.
Big help-my meter measures MV and was really good wondered about the spring but realized there were two springs in my Dual Radiant heater. The test showed it was responding to the MV output. Diagnosed it as a failure of the Dump
Switch that failed to connect on two heaters. Was cheap to replace -ordered four to be on the safe side.Now I have three heaters that all work! Good Job
thank you very much for sharing this ,I had no clu how it worked until now!
Excellent! Just what I was looking for.
Thanks. Short and sweet video.
Brilliant thanks mate. I found a gas pizza oven at the dump today and the flame kept going out every time I release the knob. You just explained perfectly what's going on! Cheers
When you press the button down, it bypasses the thermocouple and opens the pilot valve for manual lighting and when it’s heated enough you can release the button and the thermocouple will take over by holding the pilot valve open. The button itself isn’t supposed to stay depressed if the thermocouple is working, but the pilot valve should stay open if it’s sensing the flame properly.
Thanks! I wasn't getting my pilot to light on my boiler and figured it was the thermocouple. But I always wondered how it worked on the inside. Neat!
how does a thermocouple prevent a pilot from lighting....?
Great explanation & test well done
Nice explanation. I am an Electrician but never worked with gas thermocoupler.I'm interested in your stuff so i'm going to subscribe .
Franks DIY it’s a “thermocouple” that’s why you never worked on one.
Thank you. Helped a lot
Like this video very easy to explain and understand thank you!
Dude this was amazing.. thank you
Great video!
Thanks for the video! I don't care if you call the thermocouple a one-eyed wombat - you helped me fix my heater! You pebble! (Oh, was i supposed to say "ROCK"??)
That was a great video.
Thanks a lot 👍
Thank you for this information.
Excellent little demo ta old boy
!
Thanks. Very helpful
Excellent. Many thanks.
Great explanation
Thank you very much for this video, it was very useful for me
Danke von Deutschland aus, das war genau das was ich wissen wollte. --> Thank you ! That was exactly what i want to know, now i know that the elektic cycle is going over the copper and the middle Contact of brass ( it seems like brass in my case at home ) . Both are elektrically separated from the sensor to the gas-Switch. Thanks !
It's sometimes not an easy chore at all to adjust a Honeywell thermocouple on an antique gravity furnace like the one that I have, and simply because the thermocouple is not only located on the far side of the burner, it's also difficult to see in there. Actually, the best that I could achieve was 26.9 mVDC on the Honeywell 30.0 mVDC thermocouple, but I suppose it was good enough as it activated the control quick enough.
FYI Thermocouples that are good should read approx. 30 mVolts DC.
Daryl Dugger so 14 is bad then? I should replace? Pilot stays on but heat does not come on
14 is middle of the road, but not bad. Anything under 7, & you're dead in the water.
If it's 14, get some emery cloth & sand the thermopile probe clean. Shut the gas off first!
Or you can install a new one. I think they cost about $10.
thank you its realy help
Good vid. Thanks.
great video, thanks
Thank you! ❤️
My Thermo Pile & Thermocouple both test with ample milliamps. When I turn on the heat demand switch the burner does not go on. When activating the heat demand switch, the miliamps do not increase on my tester. Is this because the burner does not go on? Or is my Thermo Pile defective and the cause of the burner not turning on when I turn on the heat demand switch? The pilot light is strong and blue. I have tested the wall switch that should turn the burner and the switch tests good. What else could be causing my burner not to turn on?
I have a thermocouple issue on my furnace right now. I tested the mVolts and it climbs to 29.2mV. From what I've read, 25mV or more is considered good. I cleaned all the connections at the cold end and measure 0 Ohm from copper tube to the gas control's housing. But while heated, it still fails to actuate the plunger. A new thermocouple fixes the issue. So my thought is that open circuit voltage test is not good enough. As my old thermocouple fails while under load(ie connected to the gas control)? I'm reading 0 resistance across the plunger relay which makes sense as a relay. What load resistance would be good to test it with? And what should the current(mA) be when it's under load? I think that will tell us a lot about a TC's real performance as I know they do degrade with use. Of course my gas control is 20+ years old and may just need a peak performing thermocouple to have enough juice to drive the old plunger relay.
How many mvdc is normal for a working thermocouple.?
What if the "switch" is bad? Can that be replaces.
If you were to apply a small amount of voltage from a milivolt source to the thermocouple, would it kill the termocouple? Not to the probe but from the connector.
Hey mate, can you help me out here? if my digital thermometer is type K but my thermocouple wire is type J, i know that i will get a reading; however, how accurate is that? Is there any way to apply a correction or something else? because in my experience, by using such a set up im getting a reading with discrepancies up to 2-3°C respect to the reading obtained by using a thermometer type K with a thermocouple K.
It would have been good if you would have shown the connections you had and used that were behind the meter.
Would one on a tank top heater test the same way?
I have a 1971 Piper Cherokee 140. Temp gauge stopped reading. I sent the DG (Directional Gyro) off for repair and 50 year old temp gauge. Should test bad I assumed. It tested ok. So the new sensor and cable (4 years?). I assumed I could test the sensors like a resistor. Can put volt meter in windshield. But “sender” has to be bad. Actually, it’s simpler than that.
What is the white lead with the red clip attached to? What is the red lead attached to?
Steve Trubilla Black lead goes to the copper jacket .... the red lead goes to the lead colored tip, the white lead was just an extension I had on the red lead.
Thank you. That is what I thought, just wanted to be sure.
You didn't tell us what mV range we should be seeing! Is 5mV enough? 15?
He slept through English class! Good info though. Thanks for the video.
Is my temperature sensor wire with two leads contacted with my motherboard a thermocouple?
If so, what metals are uses and can I detect this with a multimeter
They normally call it a thermister. It’s very similar but instead of making voltage like a thermocouple does a thermister acts as a resistor. As the temperature changes the ohms change and allows the mother board to read the temperature. To test it you use the ohms setting and a lot of times the manufacturer has will tell you what it should read at various temps. A lot of times they advise you to dip the probe into ice water and take an ohm measurement at the wires.
ELECTRIC TECH Yes. I plugged in some lead wires and taped them to the leads of my multimeter looking for voltage change patterns of any kind with no success. I will see if I can get a reading with Ohms. Because this is different than a thermocouple, are there still the concept of 2 dissimilar metals in the wires?
Jesse Levine the wires are probably the same metal one wire carries voltage from the mother board to the temp sensor which restricts the voltage based on temp and the board then reads the returning voltage. A lot of thermisters I deal with are made from ceramic material but it could be anything.
ELECTRIC TECH I still have questions but, thanks for replying, subbed
What about the millivolt range that tells me that the TC is good or not?
17 - 30 milliVolts, when tip placed in a flame. 0.3 - 0.4 ohms resistance when cold, with no flame.
so my pilot lights, then goes our randomly. I installed a new thermocouple ..... it still goes out occasionally. Wonder what is causing?
rgee bee Watch the flame 🔥 make sure it’s directly hitting the thermocouple and not moving around from wind / or blower motor, if that looks good your control could possible be going bad
Or, you might have air coming back through your exhaust pipe. In this case, you might want to check your ventilation setup, and
take steps to prevent back-flow.
Test voltage. Normal operation is 17-32mV. If lower, check that the pilot flame is burning steady and contacting the tip of the thermocouple.
Check venting for obstructions and that the water heater is getting enough combustion air. When the main burner fires, the flame should be more blue than orange.
Are you running out of hot water? If you run your tank to depletion (completely cold), the water heater will condensate, and the drips of condensation can put out the pilot flame.
Less common is the gas control is at fault.
Just some ideas, hopefully it helps!
Guardian TV....Thanks much for suggestion will check it out. My furnace is a wall mounted small unit in a 500 sq ft cottage in Upstate NY, and I've had the place for 15 years....I think the unit was installed in the 80s. This is the first thermocouple I ever replaced.
thanks Pros....It's a wall mounted Sears "furnace" with a blower. I did have a bee hive in an adjacent wall last year and I think I remember moving the flu pipe and reconnecting it.....will ck it out. Also I may not have the pilot flame on the tip of the t-couple.....will ck out and fix. Thanks for suggestions
How many milivolts??? Bad thermocouples generally still generate millivolts.
nice video
Good stuff
hi, my geyser not getting automatic on off even I have changed the thermocouple & cell also.what else can be possible??? Please
Place the thermocouple facing the flame completely. If not then it's a bad valve (what he called it here internal piece) problem.. i think
Can that valve go bad on thermocouple and can it be changed. Or change whole gas valve
Peter DeCarlo they can go bad and in most cases you have to replace the entire control
how do you like that klein 2000,i just bought one.
+wade rigsbee Its great, I use this one to do all my videos because it has the biggest display. I have fluke meters that cost twice as much but this klein Meter has all the same functions and works just as good. The only thing I like better on the fluke meters are the wire leads are better quality, so I end up using the fluke wire leads on my klein meter when I'm working on customers units.
+cosmocasper thanks
Thanks for the video partner!
Quick question
Where can I get the thermocouple tester that you showed there?
Did you remove it out of a gas valve?🤔
+killer350dz you can find them online, I got mine from one of my distributors a few years ago and only cost like 20 bucks, you can remove them out the valves but they don't have treads on them like the tester does.
Very good and informative video, usually read through the comments cause I often pick up something extra, there are a lot of English proofs having a problem with your pronunciation of thermocouple, seems strange, they are looking for info on testing this thing, trouble shooting requires an analitical mind, yet this becomes a big stumbling block for them, what because of this they get so confused that the knowledge you went to the effort of sharing with a very well done video is some how not good enough, I wonder how man useful videos this group of rocket scientists have produced, jeez some people.
You didn't mention what milivolt reading you should be getting
It can vary but 25-30 is the average reading
@@cosmocasper how much amperes are generated?
even getting a 30 mv output reading on a thermocouple does not necessarily mean its good. The time it takes to reach the operating voltage is also a factor. My boiler pilot light would not remain lit so I tested it with a meter by removing he end that was connected to the gas valve and used the pilot light to heat the element . It took a long time to get to 30mv. Initially I thought it was good and that the problem might be the gas valve but I chose to replace it anyway and sure enough the one that I tested was bad.
+588158 the fact that it made voltage should hold the coil in place once lit, sometimes just unscrewing / rescrewing the end in and out of the control fixes a contact issue.
I did that too figuring it might be a high resistive connection but it didn't work. The tube was quite sooty which may have acted as an insulator hence the slow rise in voltage.
How many MV?
helpful...thanks
Thermocoupler?
After 45 seconds of applying heat meter should read 12 mV DC were more
Great video! It’s a thermocouple not a thermal coupler
The thermocouple demonstration is OK. But I am sure that the mV and small current generated by the thermocouple can never drive a solenoid. You must be having another supply which will pump enough current and voltage to drive that solenoid. The thermocouple is only giving a signal. Pl check.
thank u
@1:38 i think he has a "YIKES its hot" moment on the part of the thermocouple he put flame to. Nice video but be careful!
Thankyou white man, very cool
1:29 "powers the internal workings of a thermocoupler" there are no internal workings of a thermocouple. I assume you mean gas control valve
Gud sir
good job thanks. but there is no such thing as a hot water heater. its a water heater.
Thanx
ThermocoupleR........ Sir, I encourage to use the correct name, which is thermocouple!
Good job. However as pointed out. It is a thermocouple.
Damn my multimeter doesn’t have milivolts
Ha, you keep saying "thermocoupler"
lol ya I always do trust me I know its wrong but I just feel thats what it should have been named.
+Will Begg I grew up with my dad pronouncing it that way, bad. Habit
Will Begg n.d..dew.
Will Begg also "hot water heater" plumbers eye roll...water heater
lol “thermocoupler” “produces milivolts” “creates magnetism” .... this guy ...
There are a lot of videos similar to this. People that don't know what it is called or exactly how it works
Its "thermocouple," not thermocoupler
#EngineeringStudyMaterials
How could you be so precise and not know it’s a “thermocouple” not thermocoupler!! and it’s a “water heater”. Hot water is what it produces...sakes
Mack James excellent question lol. Well I found out a few years ago that UA-cam prefers videos that get a lot of comments and when you pronounce something wrong it gets a ton of comments. The hot water heater is just me being retarded. Bout 2 years ago I started saying it correctly “water heater”.
Warning!!!!!word nazi below.
Thermocouple. Thermocouple. Thermocouple. Not thermocoupler. Not thermal coupler.
You called it a “ hot water heater control”
If it’s hot water - why does it need to be heated? I think you mean to call it a “ water heater control “
Water heater not hot water heater. No need to heat hot water lol
No thank you!
I'm not a plumber or electrician but even I know that's a water heater....NOT a HOT water heater. If you have hot water why heat it...lol. (yeah yeah....I know it's commonly called a hot water heater but that's incorrect).
Dude! You can spell, right? There is no "R" at the end of thermocouple. Thanks for the video but you might want to do it over so you won't give a "wrong" impression. Best of luck.
Joseph Stokes well aware of how to say it but more comments on UA-cam tend to make the video get more views. So by pronouncing something wrong people naturally correct you and it causes the video to get better interaction 😀 and place higher on the search.
I have heard both even from the parts house. Just because it "aint" in the written txt it is understood. No break down in communication here.
GUARDIAN TV nice bullshit save! Iam sure that’s the reason you said it.
It's only understood by people who don't know the meaning of the word thermocouple, which is "a device that consists of the junction of two dissimilar metallic conductors" i.e., a couple of two dissimilar metals. Maybe now you understand why it's thermocouple and not thermocoupler. Another popular error is thermocoupling. If you like thermocoupler, you might also like thermobabble and thermoBS.