Commercial Water Heater

[szmut]

When the water gets to temp the pilot light goes out with the main burner. Any one know what causes this problem. I’m going to replace the valve (the heater is 10 years old).

[harv]

I noticed on my own unit at the house that the info on the side just rates the tank at 6 years(I think). Being as how you didn't say What type w/h you are referring to then I would ask is a ten year old heater worth the effort?

[spotts]

Doubt it's the valve.......... Whaddaya do for a livin Smuty?

[szmut]

I was a sheet metal for 30 years at Inland Steel in East Chicago Indiana, retired January 31, 2003. Since 1975 I have done residential and light commercial HVACR. I now work at Purdue University North Central in the Physical Plant. Chillers 250 and 500 ton, 2 200 Horse Power Boilers, Air driers, water coolers 3 Leiberts.

[szmut]

Changed the thermocouple and cleaned the pilot orifice. Pilot lights fine even with the old thermocouple. It’s when it gets to temp the pilot goes out. Good draft, in room with two 90+ furnaces with outside combustion air.

[htg guy]

Is this actually a "commercial" water heater or is it a smaller residential one?
Does it use a thermocouple or is it actually a thermopile system?

[szmut]

It a 60 gal heater with a 30 milli-volt thermocouple.

[spotts]

Could the draft be "sucking" the pilot out?

[szmut]

Flame looks ok when it shuts down.Only when it gets to temp.

I just though maybe it is over heating, is ther a safety built into the valve

[szmut]

Have to go to a class on PLC will check later.

Thanks to all

[mike3]

May be going off on ECO (stacking). Are there any water leaks on the hot side? With a small water leak i.e shower valve dripping can cause tstat to call for the burner to come on. Water temp will rise and open ECO dropping out pilot. Have you checked dropout on the power unit (magnet)?

[htg guy]

Whats the brand and model of this water heater?