No Hot Water: Water Heater Troubleshooting

How to diagnose and repair a faulty atmospherically-vented, gas-fired water heater. Common problems and how to fix them.

Example tank is a John Wood 40 gallon: Model AV40N
Same tank as A.O. Smith 40 gallon: Model GCRL 40

Status Light Codes
Normal Flashes:
• 0 Flashes Indicates Control Off/Pilot Out.
• 1 Flash Indicates Normal Operation.
• A continuous light indicates that the gas control
valve/thermostat is shutting down.
Diagnostic Flashes:
If the water heater is not working, look for the following
diagnostic flashes after lighting the pilot.
2 Flashes Indicates Thermopile Voltage Low
4 Flashes Indicates Overheat Failure
5 Flashes Indicates Sensor Failure
7 Flashes Indicates Electronic Control Failure
8 Flashes See “Status Light and Diagnostic Code
Troubleshooting Chart.”

Related Videos:
Control Valve Replacement
Thermopile Replacement
Thermopile Voltage Test

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Thank you!

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[sambro]

I just paid a guy $59 for a guy to come and try to sell me a $3k replacement job. I tried troubleshooting the thermopile isolated and then the thru the switch. The guy that came out never tried to troubleshoot anything or tell me or try to check the reset on the switch‼️ 2min into this video, I now have hot water and a happy wife, and saved a lot of money on a unnecessary purchase. THANK YOU‼️

[admiraladam]

Come home late night and No Hot Water. I immediately came to YouTube and found your wonderful video. Thank you for bestowing your knowledge to the little people. You saved me a lot of money, if I could I'd buy you a beer.

[sarahashley]

I like that your videos get right down to business with no music or long intro. I didn't come here for entertainment. I came for your knowledge! I appreciate the way you convey information efficiently and effectively. You've also saved me money! Thanks!

[tylerc]

Don't forget it wasn't that long ago that you needed to call someone out for help, but nowadays there are guys like Pat around who share their expertise with us. This video is the absolute perfect step by step checklist to ascertain _exactly_ what's wrong with your gas water heater. When it's boiled down to essentials it might not sound like much, but there's many years of troubleshooting and repairing very neatly sewn into every sentence, and it takes another person with years of experience to fully appreciate what's being offered for free. On top of all that it's so clear & concise on what to do and how to do it, that it's easily understandable to a layman, home-owner or Do-It-Yourself-er. Great video mate.

[randolphholmes]

Growing up without a dad, then becoming a homeowner, I'm so thankful for YouTube videos. Came home to no hot water and found the issue at 1:48 of this video

[codymasters]

You are awesome! Been fighting this thing for hours. I knew I should've checked YouTube sooner. I love when actual professionals are comfortable with sharing info like this to try and save the consumers some money. My family thanks you!

[tomguglielmo]

First off, I taught college Math for 42 years and can really appreciate a well prepared presentation. You get A+ in my book on so many levels. Not sure what you do for a living but you would make one helluva of a great teacher. Thank you, Thank you, a 1000 factorial Thank yous for your contribution to all of us. I was wandering in the dark for days; Pilot Assemblies, Thermopiles, 560 millivolts, Gas Control Valves, ...until I stumbled upon you and your excellent. And I too would buy you a beer, no maybe a fine cognac would be more appropriate. Something more elegant like your videos. Bravo.

[TheMusicDied]

Came home from work yesterday after a long day and was told there's no hot water. OMG, it's frustrated! Went through so many videos on YouTube but no one video mentioned about to check the thermo switch. Your video is very, very helpful! Thanks for taking the time to explain all the steps! 💯

[JoyfulGypsy]

I was able to fix my water heater quickly, instead of having to call and pay a repairman to come over in the middle of this COVID-19 pandemic. I am so thankful for your video.

[danmonday]

Thank you. First time home owner with no experience! These videos have saved me lots of money that I don't have 😊

[s.l.brewer]

I really want to thank you for this video, we are on a fixed income and having a water heater replaced is something we just can’t afford now, but after watching this video it helped solve our problem and our water heater is now working. Thank you so much this saved us a lot of money and for that I’m extremely grateful.

[Mrki]

Thanks for the video. My termal switch was triped. I vacuumed filter and around the tank, lid and now it's working. You saved me $300-400 today. Thanks again

[emosongsandreadalongs]

1:45 this is incredible!
We haven't had hot water for nearly a week. I've relit the pilot a few times in the past, but this time it just wouldn't work. Sparker is fine and lights the pilot no problem, but as soon as I let go of the knob the flame dies.

I've watched all kinds of videos online, talked to people, and prayed hard. Yours is the first video I've come across that explains the button that gets tripped. I pushed it and all my problems were solved.

Thank you, thank you, thank you!

[birdylover]

Makes me smile - comments from years ago, comments from five days ago. 1.5M views. Not bad! No uncooperative water heater is safe from this guy. I have a feeling my uncooperative has died of old age, but at least when the plumber comes to do the replacement I will be armed with questions and my own, well informed, trouble shooting review. Thanks so much, Pat.

[PROSDIY]

𝗔𝗺𝗮𝘇𝗼𝗻 𝗔𝗳𝗳𝗶𝗹𝗶𝗮𝘁𝗲 𝗟𝗶𝗻𝗸𝘀

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.

[Mordant.Melodys]

I couldn’t get the pilot to stay on and had no status codes.

All I had to do was press that switch and viola, the pilot stayed on and the unit is blinking like it’s supposed to! Thanks man. From the bottom of my heart thanks! I’m dead broke right now and you just saved me some serious cash. Some dishonest plumber may have told me to replace the water heater, and that’s a lot of cash.

[Teejaye]

Man, you are a lifesaver. Followed the steps and my switch thing needed to be reset. After pushing it, I got the status flash and my pilot lit right up. Home has hot water again!! Much appreciated my man.

[alto]

Man, I owe you a lot. I was waiting for the last 36 hrs with no hot water but your video helped me to fix that, so I don't have to wait for those crooks to come on Monday as they promised

[kdc]

Thanks! My landlord is in LA, I live in British Columbia and didn’t want to call them because I had no hot water. This video made it super simple to fix! Thanks so much! Now I know for the future.

[stephaniecolley]

Thank you for this very thorough and easy to follow instructional video. I was able to get my hot water back up and working again very easily and quickly thanks to your help!!! My whole family thanks you!!! We have a very large and always busy household! Keep on doing what you’re doing!!!