# AO Smith water heater burner wont stay lit.



## Fortypopper (Apr 8, 2012)

It is a AO Smith promax GCV 40 100 water heater to be exact. I can get the pilot to light may take a second or two to keep it light but when I turn it to the on position and turn up the temperature the burner lights. It goes out along with the pilot light after a minute or two of heating. I do hear a slight "click" when it goes out. I have tried cleaning it to make sure its not starved for oxygen, didn't help. I checked to see if its under warranty and it is not. PLEASE HELP!


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## oh'mike (Sep 18, 2009)

Is that a sealed unit (no door to the burners--clicker to light--little glass window)

or an open unit--(removable door light with a match)?


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## Fortypopper (Apr 8, 2012)

oh'mike said:


> Is that a sealed unit (no door to the burners--clicker to light--little glass window)
> 
> or an open unit--(removable door light with a match)?


Yes, it is sealed. Glass window with clicker to light.


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## oh'mike (Sep 18, 2009)

Call a plumbing supply house --you may not be able to buy the parts you need--usually only sold to licenced plumbers---either the thermo couple is dead or the flame sensor is defective---often the whole burner unit must be replaced---sorry---


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## oh'mike (Sep 18, 2009)

AO smith has a technical help site and phone number---google that--my bookmarks aren't working tonight--


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## Fortypopper (Apr 8, 2012)

Ok, thanks for replying I've posted a video to show what is actually happening. 

http://www.youtube.com/watch?v=8eIwwhKS32g&feature=share&list=UU1O5pD2vLp5LWQJopDsmOoQ


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## oh'mike (Sep 18, 2009)

Sorry--computer is wacky tonight---no videos for me---Mike---


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## oh'mike (Sep 18, 2009)

Come bail me out! One of the plumbesr here will jump in soon--I see Alan is on --there are some truely good plumbers here--one of them will be along soon---


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## Fortypopper (Apr 8, 2012)

Thank you!


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## ben's plumbing (Oct 6, 2011)

seems like a weak thermocupler ..did not see in the video if there is a tempeture sensor for cloged vent....the thermocuppling could be changed...could pick up at local hardware...


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## oh'mike (Sep 18, 2009)

Ben--I don't know about A.O. Smith--but most of the sealed units I have delt with can not use a universal thermo couple---Must be original equipment---different threads---


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## ben's plumbing (Oct 6, 2011)

oh'mike said:


> Ben--I don't know about A.O. Smith--but most of the sealed units I have delt with can not use a universal thermo couple---Must be original equipment---different threads---


 most tanks we deal with use univerisal ..except whirpool they have reverse threads....thanks for the info like you don't see any ao smiths....maybe someone else will chime in???


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## oh'mike (Sep 18, 2009)

Good news on AO Smith--It was two Whirlpools that had me stopped---AO Smiths are better units and I have never needed to service one---


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## Fortypopper (Apr 8, 2012)

oh'mike said:


> Ben--I don't know about A.O. Smith--but most of the sealed units I have delt with can not use a universal thermo couple---Must be original equipment---different threads---


Mike is right they cannot use universal thermo couples. Good news though I took out the whole assembly and scrubbed it down with a wire brush. Although it didn't look dirty...I re-installed it and its working fine now. Hope its not temporary. I thank you again for the time spent with me.


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## Gerrie (Apr 9, 2012)

*AO Smith hot water tank wont stay lit*



Fortypopper said:


> Mike is right they cannot use universal thermo couples. Good news though I took out the whole assembly and scrubbed it down with a wire brush. Although it didn't look dirty...I re-installed it and its working fine now. Hope its not temporary. I thank you again for the time spent with me.



I'm still fighting with my water tank. Going to try to bleed it first. Easter filled my days. If need be, how would I go about taking out the whole assembly, like Fortypopper mentioned?


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## oh'mike (Sep 18, 2009)

Remove the two tubes coming out of the control valve---remove the screws holding the cover plate for the burner opening--then the whole burner assembly should slide out---

The manufacturer should have a set of drawings available on line--and a parts list.

Some makers will not sell to homeowners--only plumbers---my supply house carries repair parts for many brands--call and see if your plumbing supply house has parts for your brand---


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## rselectric1 (Oct 12, 2009)

oh'mike said:


> Remove the two tubes coming out of the control valve---remove the screws holding the cover plate for the burner opening--then the whole burner assembly should slide out---
> 
> The manufacturer should have a set of drawings available on line--and a parts list.
> 
> Some makers will not sell to homeowners--only plumbers---my supply house carries repair parts for many brands--call and see if your plumbing supply house has parts for your brand---


Hey Mikey! I might just have you over to my house. (You know where I live :laughing I have the EXACT same issue going on with the EXACT same heater.

I contacted AO and they told me the entire pilot assembly needs to be replaced, but the parts are available at Ace hardware.

The thing's only 4 years old. The assembly is around 40 bucks or so.

You can't replace just the thermocouple due to a fusible link that is built in.


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## oh'mike (Sep 18, 2009)

Get the parts--I'll do it for a hot beef sandwich and fries!

Call me---The whole guts just slide out after the cover plate is loosened.


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