Raypak Versa won't light

[gemax]

I have an ancient Versa model 405B that has worked well for many years. Until now. I have replaced the ignition control and the transformer, thinking that was the problem.

What I don't understand, is the pilot it lit all the time. Even with the power removed from the unit. Is this normal? Where is the pilot sensor that signals the gas valve to open?

Thanks for your thoughts.

 

[KDpoolguy]

Is this a electronic or millivolt heater? Must be a electronic-just making sure.
I have the VERSA also, and rebuilt the electrical parts almost entirely last Fall, so it’s kinda fresh in my mind. The pilot light is always on? If so, it’s likely be the Gas valve stuck open. The gas valve, to my recollection, had a pilot routing and main gas supply routing separate. The ignition control won’t let the main gas release until it knows there’s a good pilot light.
If you recall you’ll hear a click of the pilot ignition, them maybe 5-10 seconds later a “tick-tick-tick whoosh” of the main gas release and ignition.
Doesn’t seem like the PC board which really only handles the preliminary stuff like the potentiometers and main on/off switch and circuit wiring I/o for the routing of the pressure switch, flow switch and temperature.
I had issues with a bad ground, and a simple relocation cured a lot of electrical gremlins. Try bypassing all the safety switches on the 24v low voltage line and see if you can get the pilot valve on the gas valve to open/close (makes a ‘click’ sound), or safer yet use the multimeter. Any video online for a furnace and you’ll see similar gas valves used.

 

[gemax]

Thanks, KDpoolguy.

I know I have good voltage on all the safety switches. I have 24 volts on the "upstream" side of the gas valve, but just a momentary voltage on the "downstream" side. That's why I suspect a sensor. I'm going to try to remove the pilot assembly and clean it out. I'll secure the ground as well, in case that's the problem. I hope it's not the gas valve. I don't look forward to replacing that.

 

[KDpoolguy]

That’s a good course of action. Always dreaded what I’d do if it was the gas valve, but after spending $400+ chasing down the last gremlin (replaced ignition control, PC board and sensor kit, rewired low voltage wiring, new switch and potentiometers), I found previous repair guy wired it against how it was in the manual, so it really confused me.
At that point I wasn’t even sure it’d fix it, just glad I took pictures before. Then I was thankful for TFP for telling me about the bad ground issue. With the IID valves costing $300+, I was just gonna give up and call it a loss if it was the gas valve, and get a new unit. Thankfully it’s working well. We really rarely use the gas, but I enjoy an occasional spa soak.
You can bypass the sensors and check each one, pressure switch is easy to view when pump is moving water and energized. From what you’ve mentioned if pilot light is staying on try lightly rapping on the valve with a wrench to unstick it, ive heard that before.