I think the gas valve is bad. I jumped the terminals on top of the valve to see if the unit would fire, nothing. This usually means the gas valve is bad. But, I went out this morn and jumped it again. it fired up with a small fire ball from underneath the heater. Knocked me back. The unit stopped about 10 seconds later. It never fired up again.

Curt

 

I'm guessing that this is a standing pilot model as the gas valve on the electronic ignition module needs power and shorting it would wipe out the module.

Any one of the safeties can be open and keeping the gas valve from opening. As you just found out.... there is a reason for safety switches.

 

Yes, this is my system. The pilot stays lit. I'll check the millivolts today.

 

Alex, I'll take" Clogged up heat exchanger with tripped rollout switch" for $1000.

 

What is the Rollout switch?

 

The roll out switch detects the flame when it is not contained in the burner and heat exchanger area. It's usually mounted near or right above the burner area. You had a brief flashback of flame...... had then been continued for a certain amount of time.... it would have tripped the roll out switch. Pictorial part #26 on or near page 43 in the parts breakout and location page.


Hayward-pool com/pdf/manuals/H-series.pdf

 

update.
I removed the gas valve and burner housing as 1 piece. I found a clogged gas outlet port (spider web). This was the port nearest the pilot. I cleaned the burners and replaced a terminal on the TH. The unit started right up. Thanks for all your help.