My heater will ignite when I first turn on the Heater for the jacuzzi and the burners will stay lit until the water reaches the set temperature. When the water comes down in temperature it will try to reignite and the burners will not light. Meanwhile the gas is building up and when it tries to ignite flames come out of the top and the burners still don't burn. Of course I turned the heater off. Can anyone help me out with a possible diagnoses. Thank you

Great heater; how old is it?

Did you check the flow switch? Thermocoupler? Temp sensor?

Check the ignition wire, thin blue wire that runs from the control box down to the pilot. Just had a problem like this with a cust. It would heat up fine when heater first fires and temps are cool inside the jacket. Then, when hot, a crack in the ign wire insulation causes the spark to exit thru the crack (no wheres near the pilots gas) and it sits there and arcs against the jacket till enough gas finds its way to the arc and, well, you know. You'll probably have to take the pilot out to inspect the wire as the crack will be near the pilot end of the wire.

Good Luck

Thank you for the help. I will give it a try.

Mice like to nibble on the plastic coating on the wire also. Put a box of D-con in the heater (away from the flame!) and that will help keep them out.

Pool Clown,

I am helping Lenny with this problem. He checked the ignition wire and no crack or missing insulation. Is it possible to adjust the pilot so it is closer to the burner or do you think it might be something else?

You can also check the gap on the pilot assembly
5/16 nut driver will take the pilot assembly from under the burner tray.


Taken from Raypak manual.

When it tries to light with no success, can you hear the pilot buzzing?

Thank you for your help. I removed the pilot and made sure it is set properly. The problem still exists. I did notice that the first burner line closest to the pilot is not burning as well as the rest. Only about half the line is burning and the flames are much lower then the rest of the burners. Could this be a pressure problem or something else. Thanks again for your help.

Sounds like you have a plugged (partially) burner, Lenny. Did you take the burner tray out and clean it? You have a pressure regulator, so you should be even across the tray unless something is plugged up. Maybe you can try and vacuum it good before you take it out. Since it is the one closest to the pilot, that is probably a pretty good reason that you are having erratic ignition.

Hope you get it fixed soon! These things get more frustrating the longer they seem to go on.

If you are so inclined:
Look under the burner tray and see if you can see the jets sticking out from the header. The jet shoots gas into it's own burner, they run from just past the jet towards the back of the heater. If you can see the opening of the burner, try taking a length of wire and slide it into the burner. What happens sometimes is spiders will make a web in there and the gas can't pass the web and therefore won't light the burner completely. If this doesn't work, the jet itself has the web in it, and the burner tray must be removed and the jet in question needs to be removed and cleared. Usually, if your going to take the burner tray out, you should take all the jets out and check them. I know this sounds kinda vague, but if you want to try it, i can try to post some pics of this for you Thursday or Friday, Out of town tonight.

I removed burner tray and jet. There was a spider nest in jet. Heater is working great now.

Thank you everyone,

Lenny

I know this is an old thread, but wanted to report it helped me with same issue! Heater would cycle normally, you hear the Click, Gas Valve opens, SPK (the Pilot Light would light up), then CFH (call for heat). It would then build up so much gas before lighting the burners, that it literally "blew it self out" (including the Pilot Light), which, in turn, triggered the Pilot Light Safety, which turns the gas off within 8/10th's of a second, only to cycle through the entire process again. Eventually, it might light, and stay lit, but the huge ignition of all that gas was certainly not a good thing. Pulled the burner tray, found the first two gas jets in the row of burners had clogged jets (spider nests in the hole) that looked like a q-tip was jammed into the jet. Cleaned them all out, and it runs perfect again! By the way, I have a Raypak P-R406A-EN-C as well.