266A Raypak Millvolt -Pool Heater Pilot issues

[thah]

I have to issues with Pilot looking for guidance. Gas Knob must be depress to sustain Pilot- when I release the Pilot goes out. With knob depressed Pilot stays with over 500++mv reading with both leads disconnected from valve. Attach one thermopile lead to valve sustain 500mv; when I attach both thermopile leads to valve I get ZERO mv reading.

Thermopile is fairly new; all leads/connections have been cleaned.
TDAH

 

[ajw22]

Welcome to TFP.

Read RayPak Heaters - Further Reading

Check the ohms on the limit string as described in the link.

Maybe @swamprat69 will wander by and provide some ideas.

 

[1poolman1]

I have to issues with Pilot looking for guidance. Gas Knob must be depress to sustain Pilot- when I release the Pilot goes out. With knob depressed Pilot stays with over 500++mv reading with both leads disconnected from valve. Attach one thermopile lead to valve sustain 500mv; when I attach both thermopile leads to valve I get ZERO mv reading.

Thermopile is fairly new; all leads/connections have been cleaned.
TDAH

Sounds like a short in the wiring or at a device (hi-limit, pressure switch, etc.). It can even be in the temperature control/t'stat.
Temporarily jump each device and see if the problem goes away.
NEVER operate a pool heater with any of the safety devices bypassed, they are there to keep you from harm.