Main Burner won't stay lit

[jim2754]

I have an AO Smith 50 gallon hot water heater with a power vent.
The power vent starts and the main burner lights but only for a minute or two. The power vent continues to run and every so often the main burner will light then go out. The pilot stays lit the entire time. Any ideas?

[chandler]

Do you have a hot water recirculator installed? I had a customer who had the exact situation. A plumber disconnected the faulty recirculator and the burner stayed lit.

[DaVeBoy]

I have an AO Smith 50 gallon hot water heater with a power vent.
The power vent starts and the main burner lights but only for a minute or two. The power vent continues to run and every so often the main burner will light then go out. The pilot stays lit the entire time. Any ideas?

Just a guess: maybe has a flame sensor with electronic ignition that has failed. If it has one, you can maybe just brighten the probe with steel wool. Let us know what you find.

[hankhill6018]

Is this an oil fired or gas fired powervent?

I've seen faulty pressure switches cause similar problems on the gas fired units. What will happen is the pressure switch sticks. You can usually blow through the tube gently and clear it up.

Another possiblity on the gas units is a faulty high limit in the stack outlet.