AO Smith FCV 50

[V.Hall]

The pilot light started going out during the heating cycle. If I kept on relighting it until the water was hot the pilot light would stay on for several days while heating small amounts at a time. The pilot light started going out on a regular basis and it go to the point it wouldn't stay on. I replaced the thermocouple and still had the issue. I also replaced the thermostat controller and still not better. I vacuumed out the bottom and around the base also. I can get the pilot light to ignite but it will only stay on when I have the button pressed down.

Any ideas??

 

[Master Plumber Mark]

how old is this water heater??

I dont think this unit has a high limit button on the firewall, but there is some sort of high limit on the SPECIAL thermocoupling...
did you install the right thermocoupling back into the unit... ??
Usually you have to buy the whole burner assembly for about
$50 bucks which comes with a new thermocoupling and burner assembly put together???
I dont know or think any thermocoupling will work correctly except theirs.....


If you have already changed everything out on the heater , the only 3 things left to do is change the burner assembly
check the flu pipe for a good draft, and last make sure that your gas meter is not sticking. and you have good flow to the heater.

last alternative is to change out the heater... how old is it??..

 

[Sponsor]

 

[V.Hall]

how old is this water heater??

I dont think this unit has a high limit button on the firewall, but there is some sort of high limit on the SPECIAL thermocoupling...
did you install the right thermocoupling back into the unit... ??
Usually you have to buy the whole burner assembly for about
$50 bucks which comes with a new thermocoupling and burner assembly put together???
I dont know or think any thermocoupling will work correctly except theirs.....


If you have already changed everything out on the heater , the only 3 things left to do is change the burner assembly
check the flu pipe for a good draft, and last make sure that your gas meter is not sticking. and you have good flow to the heater.

last alternative is to change out the heater... how old is it??..

it's 10+, The same issue continued to happen when I replaced the thermocouple so I put the old one back in. I opened the firewall to see if it was an airflow issue and it didn't make a difference. Would changing the burner help the pilot light?