A.O. Smith Gas Water Heater Model FSG 40 242

[wilkinson]

We just returned from vacation and there was no hot water. I checked the pilot light and it is on and if I turn the thermostat dial up the flame will light on the main burner. The water is only luke warm. Any ideas on what I need to do to get hot water?

[RegUS_PatOff]

[user=6770]wilkinson[/user] wrote:

... the flame will light on the main burner. The water is only luke warm...

does the Flame go out at that time ?

depending on it's age.. could be a lot of sediment built up on the bottom inside if the Tank ...

Flame goes ON, heats the sediment quickly ... shuts OFF, with slower heat transfer to the Water .. 

 

[wilkinson]

The flame on the main burner will stay on until it gets the water luke warm. If I run the hot water from a faucet for a long period of time the main burner should automatically come on. Right? It does not. The only way I can get the burner to come on is if I turn up the temperature on the dial. Could this be a thermostat problem?

[RegUS_PatOff]

could be..

 

I didn't check the model number, but depending on age,

it could also be a deteriorated "sacrificial anode" (cold water Dip Tube)

so then the incoming cold water goes directly over to the hot water exit rather than down to the Burner ..

[wilkinson]

I checked the aerators on a couple of water faucets and there were no plastic particles which might indicate the dip tube is ok. Would the thermocouple have anything to do with this problem? I looked at a video on youtube and it looks like a fairly simple procedure to change one out. However, if the thermostat is the problem how do I go about checking it? If it is defective is it a difficult job to put in a new one?