Thermopile Replacement on a Water Heater

How to replace a thermopile on a water heater. Since almost all major brands of atmospherically vented water heaters have switched from a thermocouple to a thermopile system, here's a step-by-step tutorial on replacing your thermopile.
Example tank is a John Wood 40 gallon: Model AV40N
Same tank as A.O. Smith 40 gallon: Model GCRL 40
Many other models from A.O. Smith, John Wood, GSW, Whirlpool, State, Kenmore, Reliance, and Bradford White use the same pilot assembly and procedure.
How to Test a Thermopile's Voltage
Click Here: • Testing a Thermopile o...
𝗔𝗺𝗮𝘇𝗼𝗻 𝗔𝗳𝗳𝗶𝗹𝗶𝗮𝘁𝗲 𝗟𝗶𝗻𝗸𝘀
Thermopile Assembly 100112330: geni.us/3cNfKAQ
Thermopile 100112328: geni.us/Pv4ww
Please check to see if the above part numbers work with your water heater before ordering. Visit your water heater's website to verify or cross-reference.
𝗦𝘂𝗽𝗽𝗼𝗿𝘁
Want to support my channel or give back? Help me improve on these DIY videos by making a financial contribution. All contributions no matter how small are greatly appreciated!
ko-fi.com/prosdiy
Thank you!
𝗖𝗼𝗻𝗻𝗲𝗰𝘁
More DIY videos! www.prosdiy.com
Facebook: / prosdiy
Instagram: / prosdiy
Subscribe: / prosdiy
Amazon: www.amazon.com/shop/prosdiy
Disclosure: Pros DIY is an Amazon Associate. We earn a small commission from qualifying purchases through our affiliate links at no additional cost to you.
Videos produced by Pros DIY (www.prosdiy.com) are provided for informational purposes only. Please check with all national, state, provincial, and local codes and regulations before attempting any work. Pros DIY does not assume any responsibility or liability for any damage or injury from the information provided in our videos. Please hire a licensed, certified, professional.

[@RamiAgonistes]

Hands down one of the most comprehensive and professional DIY videos I've ever seen on KZbin. Excellent job!

[@PROSDIY]

Thanks Rami!

[@juniorjake3818]

I dont mean to be so offtopic but does anybody know of a tool to log back into an instagram account..? I stupidly forgot my login password. I love any tricks you can offer me

[@castielmekhi5063]

@Junior Jake Instablaster ;)

[@juniorjake3818]

@Castiel Mekhi thanks so much for your reply. I found the site through google and I'm trying it out now. I see it takes quite some time so I will get back to you later when my account password hopefully is recovered.

[@juniorjake3818]

@Castiel Mekhi It worked and I now got access to my account again. I'm so happy:D Thanks so much you really help me out !

[@dansherwood1399]

One bit of helpful advice for those who believe they are having a thermopile/couple problem First off though, very well done. Thank you for offering up a complete guide on how to access everything. After I took the burner plate assembly out and was already convinced my thermopile was malfunctioning, I decided to clean it first. It didn't even look that dirty but I cleaned it up, reassembled everything and my pilot would light the burner and give me the single blink on my status light. I saved myself extra steps and a run into town to find the part. Some of you watching this video may want to try to clean your thermopile first and see if that does the trick if you believe you have a failure with the component. You don't have to disemble it to access it to clean it either.

[@DadManDoes]

I'm glad I read your comment. I literally JUST took this all apart and sandpapered off some white deposits from the ignition and figured "why not", I put it back together and it worked !!! I don't even need to buy the $12 part. (Not today anyway, maybe it'll go bad tomorrow) . Thankyou for this comment. Crowd-funded information saved the day.

[@heatherscrazylife9813]

​@@DadManDoes$12!?!??!?!?!! Where do you live! Mine cost me $57 😢

[@DadManDoes]

@@heatherscrazylife9813 Lowe's has a thermocouple for $12. Sucked it was the wrong one. The real one cos me $53.

[@montrellthompson5281]

Cleaned it fired right back up no need for replacement 💪🏾

[@TheEverydayPreacher]

How do you clean it without disassembling it?

[@scottwilliams2094]

This is probably the best-done DIY video I've ever seen. Very comprehensive and thorough in the step-by-step process, but explained simply enough to be accessible to any DIYer. Speeding up through the mundane steps allows us to see the repair process in full and in real-time, yet truncated so we don't have to sit there twiddling our thumbs. Thanks for the great service.

[@PROSDIY]

Thanks for the great feedback! Cheers!

[@lisasperry2771]

Perfect walk through, managed to do this as a single mom and save myself who knows how much! Thank you!

[@PROSDIY]

Thanks Lisa! Nice job on your repair!

[@torigonzales3373]

Were can u get this piece at

[@zomni1]

@@torigonzales3373Lowe’s

[@rajnanara1213]

I wanted to thank you for this video. I watched it about ten times and it made it easier to do it myself as opposed to hiring a plumber. Very detailed and easy to follow. Thank you!

[@jeffrobinson4333]

Thank you times a million!!! I’ve been fighting with my flooded hot water tank for three weeks! Between not being able to find the correct parts and not being familiar with the newer breed of water heaters, it’s been frustrating! Thanks to your video, everything’s back to normal. Thanks again!

[@PROSDIY]

Glad the video helped out! Thanks for the positive feedback Jeff!

[@tompayne695]

Well done. In 60 years, this is my first thermocouple failure, A O Smith electronic heaters are junk, we have replaced regulator with your help now a 4 YO TC. THANKS.

[@tjinytjiny6615]

Excellent video. I changed my thermopile 2 days ago and still wasn’t getting anything. Thanks to your video I realized I had not fully seated the thermopile. I just went back in at 1240 am seated it fully, and it works. THANK YOU! Hot shower coming up tonight!! 🙏🏽

[@christopherkirk6493]

Thank you for this! Did this replacement with your video playing, pausing at each step and had the heater fired back up and running within an hour. Great video, well done!

[@SSThunDerHawK]

Thank the lord!!! I found my actual hot water tank on here and its the best repair video of em all. You sir rock!

[@photophreak8]

I thought I was ordering just the thermopile but they sent me the whole lighter assembly. This video helped me tackle the job successfully. I was always afraid to mess with gas but it was really easy. GREAT VIDEO!

[@salvatoresireci2450]

This is the exact model of what I have and what I needed to get this project done. Much appreciation 👍

[@stevehammond7123]

Great DIY video! Simple, thorough and to the point! Thank you very much for posting it! The black plug on mine was stuck tight and wouldn’t budge with up and down wiggling. I hooked my fingernails in the little crevice on each side and pulled outward while jiggling it hard from left to right and it eventually popped out. Came out hard all the way though. Thanks again!

[@dansherwood1399]

Same with mine, I was worried I was going to break the thing while taking it off.

[@jcd747]

Great video...saved $100s; hardest part was finding a replacement thermopile in less than a week. Many so-called plumbing professionals wouldn't even touch this relatively easy fix in our area.

[@rhihodag9873]

So, so helpful! Perfect process for replacing the thermopile. Short - Sweet - To the Point! Thank you very much for this vid!

[@marchepburn3775]

Awesome. To the point video!

[@charliewatt3218]

From a retired Carpenter to a plumber Great job and video buddie. Thanks for sharing your wisdom.

[@PROSDIY]

Thanks Charlie, I appreciate it. Cheers!

[@user-bx5wv4ct1n]

Im 61 and cleaned my old pilot assembly myself and put it back in and it worked! Have a new coming as it is under warranty so this will for now...Thank you!

[@tommienorthcross-el1175]

im 63

[@TheEverydayPreacher]

How did you clean it without disassembling it?

[@rmdelbridge]

One of the best DIY videos I've seen - great lighting with easy to follow directions.

[@chokedoutlie]

Just completed this replacement thanks to your video. Thank you very much for taking the time to demonstrate and explain the process perfectly!

[@XRAYVIZION3000]

I'm about to change mine out in the morning or next couple of days! This video is exactly what I'll be watching while I do! Thanks!

[@Brandon-eq7hk]

How did it go?

[@crazycutty]

Thank you so very much! After watching your video and following your instructions, I was able to replace the thermopile and fix my problem and avoid costly repairman charges. THANKS!!!!

[@PROSDIY]

Glad the video was helpful! Cheers!

[@edwardnorton7463]

Excellent video! Gave me the confidence to tackle my own water heater repair.

[@joeyv5766]

Straight to the point thank you so much for not wasting my time. Keep up the good work

[@jeffreyholmes3261]

Very thorough, I watched both this vid and the gas valve replacement as I am off grid and use l.p.g as a fuel. I tested the components in my Reliant water heater, and apparently it is just the board that is faulty. That board is unavailable, so I purchased an entire gas valve. I figured, as I do with mechanics, If I have one bad set of rings, or a bad valve, it's the entire bottom or top end to ensure that it works until race day. Well done, this will be a cake walk now, and I feel secure about what I am doing. Thank you

[@larrybryant331]

This is just what I was looking for. You explained this procedure excellent and to the point. Well done sir...

[@PROSDIY]

Thanks Larry!

[@alfonsosterling133]

Thank you for the very informative video I just completed my repair and I am so lucky to get this done with your guidance because the warranty was up..😀👍

[@PROSDIY]

Hi Alfonso Sterling, I'm glad the video was helpful. Nice job on your repair! Take care!

[@scottmullins6464]

Thank you so much for the helpful video. I followed it step-by-step and was able to change out the thermopile on my water heater and fix it myself. The save me several hundred dollars thank you

[@PROSDIY]

Thanks for the positive feedback Scott! Nice job on your repair!

[@beginagainben6276]

Dude thank you. Just did this at 7am. Your explanation and video was super helpful.

[@infidelmeister]

This guys doesn't waste anybody's time! Well done.

[@ferdinand0541]

Excellent tutorial. There are other good ones, but this is the best. Thank you.

[@garrywatman1921]

Best demonstration yet!

[@PROSDIY]

𝗔𝗺𝗮𝘇𝗼𝗻 𝗔𝗳𝗳𝗶𝗹𝗶𝗮𝘁𝗲 𝗟𝗶𝗻𝗸𝘀 Thermopile Assembly 100112330: geni.us/3cNfKAQ Thermopile 100112328: geni.us/Pv4ww Disclosure: Pros DIY is an Amazon Associate. We earn a small commission from qualifying purchases through our affiliate links at no additional cost to you.

[@lblumenstein1]

Great instruction, easy to understand both video and narration. I followed and installation successfully.

[@sru9655]

Hi when I click the link I see reliance brand instead of state or Ao Smith , wondering if they are compatible or the same part.

[@PROSDIY]

@@sru9655 Hi Srujan, most water heater thermopiles are universal. They are all designed to produce 750mV. The only difference is the wiring termination connection into the gas control. If yours matches the termination in the picture on Amazon then it will work. Thanks for the great question.

[@jasoncross9857]

You are a lifesaver. That you so much. The world needs more people like you

[@jamiramsey783]

Great video with no excess babble. Very informative, clear and to the point.

[@PROSDIY]

Thank you Jami!

[@timgoudy662]

Great video. Used for reference and took about 20 minutes to replace the thermopile.

[@PROSDIY]

Nice job on your repair! Cheers!

[@Mafioso629]

Nice bike bro! I started doing mechanics on my motorcycle, then graduated to my prius, now I'm working in home repairs! Thanks for the great video! Wish me luck!

[@barryngo1950]

Great video learned all that I needed through you presentation! Thanks a bunch!

[@skinnypup1]

Best diy video ever. no nonsense, excellent information, and instruction. big thumbs up here.

[@PROSDIY]

Thanks for the positive feedback! Cheers!

[@deadmeatpuppet666]

Nice example. Helped me out, Also my thermal reset switch literally broke. Gonna take 6 weeks to get a new one. So I ghetto fixed it by taping the power leaded together with elec tape for a temporary fix. Will turn it off every night until new switch gets here but to hell with cold showers.

[@Rextrent]

This is shockingly to the point. I almost didn't know what to think, but quickly just paid attention and started looking for tools so I could get on with it. Exactly what was needed. The quite old unit I am working on has four hex head screws to remove, and I removed the gas tube at the lower entry, which had two tiny 1/4" hex heads holding it to the Thermopile. The upper brass reducer bushing was not budging and not a good idea, as it looks kind of melted together, it's old, but the two screws below were a cinch. They would have been for someone else, Fingers just can't keep up with my usual tempo, and going all slo-poke grandpa doesn't appeal. Plus a non-hygenic cellar floor w/ glass bottle shards for ground cover, samples of intimidating dirt flakes, misc. nastiness, and a pervading stench that motivated quickness and a prophetic vision promising a world w/o it as soon as reasonably possible. Gratitude makes a necessary appearance, starring in "You don't know what you've got until it's gone". The sick reality of it is that I could acclimate to stink, and it would have happened for so many people before plumbing, I'm guessing. Can't admit to reading history passages concerning stench from many sources back in the day. Shakespeare likely mentioned it in some cool Shakespeare fashion using an olde smart reference which kept the audience feeling dignified in the middle of a shared common confession of everyday humble vulnerability. NIce Video! Thank you.

[@ar2691]

I liked the way you explained and showed what you are talking about. Thank you.

[@medicbabe2ID]

Thank you x a million. Comprehensive and intuitive video. Helped me fix my problem, saved me a lot of money and time, and added to my knowledge base. Aces.

[@jeremywhite1062]

Great video, thanks for the step by step, water heater went out over the weekend while I got a dislocated rib and this Corona virus going on. Found one place in town this morning that had entire pilot assembly in stock, got it installed and a hot shower after was great

[@PROSDIY]

Thanks Jeremy. Nice job on your repair! Wishing you a speedy recovery. Take care.

[@jeremywhite1062]

@@PROSDIY thanks it went out Saturday night, immediately everyone told me thermocouple was bad, raced to lowes and barely got it before they closed, only to get home and find mine takes a thermopile instead and no one in town carries those, luckily one place had the entire pilot assembly

[@PROSDIY]

Glad you were able to source the part. It's becoming harder and harder to get parts with the whole COVID-19 thing happening. I currently have to phone my distributor for parts and they pick the order. Then the order is left outside for a scheduled time for pickup. Amazon has become more and more my friend lol. Stay safe

[@peterbminett7579]

Need to change out the thermopile on my gas fireplace. This is the closest I could get to what I really wanted - that conclusion comes after watching a couple of other thermopile related videos. This gives me a good idea of what to watch for as I disassemble what I've got, and how the parts fit together, come apart and go back to together. Quite useful. Thanks

[@PROSDIY]

Thanks Peter, I hope your project went well. It can be very frustrating working with fireplaces as there's not much room to work. Fireplace thermopiles are a little bit different, but serve the same purpose. They are usually held in place by a threaded connection into the pilot assembly. They also have a spade terminal connection at the end of the wires. Thanks for the comment! Take care!

[@arielsoper7886]

OMG Becky you just saved my life. Soo helpful.

[@halraines9]

I think this is one of the best DIY videos I've ever seen. Thanks for your help. I'm generally not a DIY w' plumbing/water heater items. This video is straightforward and feels doable. I will do this.

[@PROSDIY]

Awesome! Good luck on your repair!

[@murrayvt]

How lucky am I, the water heater in your video is the exact same model as mine. So this made it extremely easy to follow because everything is the same. Awesome video, even though it's 4 years old it is still super useful. Thank you.

[@thefudfarm]

Where did you buy the part ? I went to Home Depot and they don’t have this one.

[@jp040759]

Thanx. Looks these things are easy to repair. From other videos that I have seen the Honeywell control valve sucks. Lots of videos out there that explain how to reset the controller from a VERY common 4 flash error code. View them before you waste money on buying a new control valve.

[@lilchickdi]

Thank you so much for this super informative video. You help me fix my water heater and save time and money!

[@PROSDIY]

Thanks Crystal! Glad the video was helpful.

[@cmathis208]

Made my repair so much easier! I appreciate the detailed videos.

[@johnpan78]

Thank you for the great video and step by step description.

[@PROSDIY]

Thank you John pan!

[@bobboley5501]

Fine, fine job. This should be the standard for how to vids. If it's not too much trouble, could you make one of these for everything?

[@PROSDIY]

:) Thanks Bob!

[@amandaheaton9237]

yes sir, i fixed my reliance water heater thanks to this video,i actually only had to clean off probe thingy mabob lol & blow dust out of everything, thanks a bunch bud

[@jasminemeichsner186]

Wonderful video. I have a AO Smith water heater that matched your video. I went in and replaced the thermopile successfully without getting stuck. My first ever water heater repair! Your video was a great instruction, with identifying the different steps and also displaying them clearly. Thank you. Mild criticisms: ** you say "use the right sized wrench on the brass gas bolts" when the video shows a crescent wrench. However, I didn't have the wrench for the larger sized brass bolt on the main gas line and my crescent wrench did work very well. ** I struggled getting the clip off the "pilot light assembly" and didn't get how the person in the video did his. ** In other videos, they show ways of checking for gas leaks, maybe include this info in future videos.

[@devangshah8700]

Thank you for uploading this video. I follow the instruction and it work perfect.

[@PROSDIY]

Thanks DEVANG SHAH!

[@billybob7145]

Very helpful and professionally presented. Much thanks!

[@golf-freq]

This is an EXCELLENT instructional video -- thanks!

[@PROSDIY]

Thank you! Cheers!

[@VeryMuchBlessed]

Excellent and very helpful video. Thanks much.

[@robstone3002]

Excellent video. Very clear and perfectly paced.

[@PROSDIY]

Thanks Rob!

[@cndjx]

Excellent Presentation! Thank you!

[@PROSDIY]

Thanks Jose!

[@DadManDoes]

This video juat saved me hundreds of dollars. Also, if you take it apart and the ignition and couple seem fuzzy with white deposit, take some fine sandpaper to it. I did and it worked. I didnt even need to buy the part.

[@juanquintanar4358]

Excellent VIDEO!!! Thanks a lot. Very good explanation.

[@quijanoguillermo1632]

Straight to the point! I love it!

[@rogersmith3443]

Thank you so much !! Followed the video to the "T" and everything wotks great !!!!

[@PROSDIY]

Thanks for the great feedback! Glad the video was helpful. Take care!

[@justinsmith2541]

@@PROSDIY Followed to the T as well but my shit doesnt work...

[@chrisperanich]

Excellent walkthrough. Thank you very much

[@bifomo8327]

Very professional! Thanks!

[@ignaciogutierrez6729]

Thank you for making a very detailed video, highly appreciated 👏🏼

[@a.per9612]

Excellent video and very helpful Thank you!!

[@clintonmcclure3079]

Thank you for helping me fix my water heater!!

[@rennexmachina5272]

Thank you! 👍👍 For the next 24 hours you're my favorite person on this entire planet! 😲 Cheers! 🍻

[@jester4453]

excellent video....no extra b.s. Very thorough!

[@cleavitt1003]

Thanks for the visual lesson. Ill have it swapped out in 20min

[@lion91355]

Great video my friend Very helpful in repairing water heater You have a pleasant voice and patience while explaining steps delicately 👏👏🙏🙏🙏

[@josephfnieto8481]

Thanks much appreciated. I have my backflo testing lic and repair but know nothing about water heaters until now peace from Califas

[@leishaabercrombie5351]

Very informative and professional. Thank you

[@ignaciogutierrez6729]

Thank you for making a very detailed video, highly appreciated..

[@davidlyons7238]

Excellent video. This was the same as the Aosmith I worked on yesterday. Now I know what to do if I have to deal with it again. Thanks.

[@russoft]

technician who visited my house wanted to charge $600 to do this. I said "I'll think about it" and then started searching youtube.

[@jamestrementozzi]

Awesome, I just completed the repair for $15.

[@jp040759]

For $600 you could buy a new water heater. But the labor would be another $600. LOL.

[@GofGisMFA]

@@jamestrementozzic8$

[@jamescarrington5521]

That's because they're smug; they've got it all sewn up...or so they think. I've been installing my own HVAC and water heaters for close to 30 years. Fuck that crooked noise!

[@cleavitt1003]

I believe everyone is entitled to a fair wage and or profit whenever a business or individual is providing a service to the public. What I don't believe in is GREED! 600.00 dollars to install a 20 dollar part in less than 15 minutes. Hmmmmm.....let me sleep on that. I'll get back to you tomorrow. NOT! Whats more, the service provider probably gets those Thermopiles in bulk for 5 dollars ea. and for some reason feels entitled to a 100 to 300% markup in its retail price. Then charge for 2 hrs of labor (@ 150.00 p/hr) because somewhere in a plumbing for dummys manual, it states a worst-case scenario time-frame for completion of this task for a beginner homeowner with no prior experience. 😅

[@tonywall540]

You said hooked the shorter wire to the left side but what if mine is up up and down ones on top of ones on bottom the video is very helpful but I'm still wondering if I put the shorter wire on top or bottom

[@86dmo]

You are the man!!!!!!! Exactly what I needed to know!!!!

[@libreverdaderamente4450]

Great video , Thank you !!

[@davidpaynter3231]

This one helped me the most. Thank you.

[@chrisk.6849]

Nice video. I’m a service plumber couldn’t explain it better myself

[@PROSDIY]

Thanks Chris!

[@r.s.737]

Thank you, great video very detailed and you explain it very well

[@dntlss]

Hey, i had a question, im doing this right now and when i pulled the burner assembly out that black gasket came off in places,its all together and its still in decent shape but i would like to reattach it to that piece of sheet metal, a few years ago i was working on my furnace and i bought some bad to the bone red rtv thats supposed to be high heat,you think it would be ok to just barely place some of that and reattach the black gasket to the burner assembly? you can see that big square gasket real good at 1:08 in your video, thank you much for your time.

[@rexcheng6504]

Thank you Thank you Thank you!

[@mattharrod9379]

Thank you. Deeply appreciated.

[@jerrymaushard3835]

Well done!! thank you very much exactly what i need to do.

[@drock5108]

Yup I just replaced mine and watched this video step by step !👏🏼great video! U get a 👍🏻!

[@marymcnamara1995]

This made it really easy for me thank you for the safety tips also

[@justinmatthews5337]

Thanks for the nice easy video!

[@vanluong1392]

Excellent Video. Thanks

[@ctdieselnut]

My thermal breaker kept popping causing the light not to flash even after the pilot was lit. Ended up being the exhaust stack had a mouse nest in the end blocking the draft enough to trip the thermal switch. I had turned off gas to the house for a week for something unrelated, enough time for them to block the pipe. Thanks for the vid, I needed to know the name of the thermal switch to even search what to do. Thumbs up! I hope maybe this post helps someone else in diagnosis of there non blinking light.

[@thewaterheaterfactory]

You nailed it! One thing though , I recommend removing the wiring harness from the circuit board with needle nose pliers , rocking it back and forth is risky and loosens connectors up needlessly. Otherwise Great video same process on most burner assembly's too!

[@johnfisher9969]

Great video! I have hot water again. Thank you!

[@PROSDIY]

Thanks John! Glad the video was helpful!

[@ForgivenReverend]

Another great video man. Thank you.

[@wingslevel]

How come these only fail on the weekend? Also found out that these have a reset so be sure to check for that before replacing thermoplile.

[@PlayVintageGolf]

Very helpful, but the light on my controller never comes on. The pilot lights fine, but never stays on when I release the button. Any suggestions? I assumed it was the thermopile, but I just changed it and same thing.

[@sh2697]

it is hard to just buy the thermopile without the kit, can I hard wire the red and white back to the plug?

[@mrtwister9002]

So, pipe dope is not needed for the fittings that are installed in the water heater thermostat, correct?