Raypak 405 Help Please

Dec 26, 2015
1
Houston
I have a relatively old Raypak 405AL. It does a fine job when it works. Here in TX we only use it maybe half a dozen times a year to go in the spa in the winter months. Not used a lot.

The digital LCD screen became unreadable a while ago, but I put in a pool automation system that shuts the heater on and off as needed, so I haven't worried about it. That may or may not be relevant, as it worked fine for a number of years.

Last year, the system had trouble going to full ignition for heating. The gas would ignite alone the burners, but the blower would start and blow it out. This would happen a few times until it seemed to warm up enough to stay lit. That brings us to this year.

Turn on the heater, click and pilot starts, then the usually buzzing when the burners usually start, but it never lights. Blower never goes. I jumped the "TH" connection and no joy. I also tested the MV-MV/PV voltage, but only got 14.5. I am a complete electrical novice, so not sure what that means except I think it was supposed to be 24V (AC I assume, or DC, I'm not sure). Does this mean I need to replace the gas valve? And I broke one of the rusted electrical tab connections on the gas valve - so it has to be replaced anyway. Is this a home handyman job?

The unit is old. if the gas valve will fix it, I will try it (even if I need a pro) because I can spend a couple hundred bucks to have the spa this winter, but don't have 3 grand+ right now for a new heater (Just had a $2000 repair on one car and had to replace another). The option is wait until sometime next year and hope finances are better.

What should I do?
 
Sounds like maybe you have an obstruction in the unit that it's drafting down blowing out the flames.

As for the gas valve, yes I would replace it since a terminal broke off and I would NOT use a handyman to fix it. Get a licensed gas person to do it. If you don't have a local company that does Raypak work, then maybe a HVAC company can take care of it for you. You should have 24V at the valve.

I would also pull the burner tray out and inspect them as well as up inside under the heat exchanger. Then also check ut the top of the heat exchanger as well for any obstruction. Maybe heat exchanger is sooted and needs to be cleaned.
 
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