Raypak 156A Explosions upon lighting

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Rack55

Active member
Aug 14, 2018
41
Ottawa
I have a Raypak 156A propane heater, 5 years old. Constant problems every spring.

Currently it will not light, and produces a small explosion in its attempts. I’m not sure how else to indicate that.

The pilot will spark and light, but when the main burner attempts to light, there is a big poof and everything restarts. Each subsequent light attempt results in a bigger poof. I shut it off, give it time to clear out and cool down and start again with the same results.

I have tried adjusting the water flow into the heater with no success. When taking apart the header it feels like the bypass valve spring is loose, but I’m not sure what the baseline is on that. I am fairly certain there is water flowing through the heat exchanger especially with my 3-way bypass on full send to the heater.

Has anyone experienced this or have any advice on what may need to be adjusted or replaced? For context, it has sat all winter and I have not had it up and running yet this year, although I it worked fine last year before shutting down for the winter.

Thanks!!
 
Explosive ignition is usually caused by the burner right at the pilot burner having a clogged orifice. Spiders love that particular one in any pool heater. Gas from the other burners eventually gets to the pilot, but by that time there is a lot in the chamber and you get a "boom."
Burner tray has to be removed to clean the orifice with a #14 solid copper wire. Copper won't scratch the orifice and will fit into the opening.
 
Well I guess that’s not as easy as I hoped. I have to disconnect the gas line to remove the burner tray and I can’t seem to do that. It’s a double male threaded pipe so I assume one is reverse thread, and turning it just torques the whole assembly around. This heater is a problem.
 
Last edited by a moderator:
Not really, it is attached to an elbow on the outside, then straight into the heater unit inside. I assume the elbow is a standard thread and the connection inside is reverse thread. Investigating.
 
Ok so I just spent all day working the gas line loose and finally getting the burner tray out. It was very Rusty and there was a spider climbing around.
Scrubbed it with a wire brush, then shop vac, then compressed air. Removed all orifices and blew each one out on its own as well as the entire assembly.
Rebuilt the heater.
Turned it on…. And poof, the exact same explosion as before.
 

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Rack55 said:
Ok so I just spent all day working the gas line loose and finally getting the burner tray out. It was very Rusty and there was a spider climbing around.
Scrubbed it with a wire brush, then shop vac, then compressed air. Removed all orifices and blew each one out on its own as well as the entire assembly.
Rebuilt the heater.
Turned it on…. And poof, the exact same explosion as before.
Click to expand...
Was the main valve ever changed? If this is propane the valve MUST be one set up for propane. A natural gas one lets too much gas through and could cause the issue.
 
The unit is tied into my 2 400lbs propane tanks for the house. The gas valve is definitely the propane valve, clearly marked. It’s 5 years old and although it has come with many issues, this is the first time I’ve experienced this one.
 
Is there a better way of cleaning the burner than what I did? I gave it a good scrub with the wire brush, lots of vaccuming and blew every bit out with the air compressor. Reamed every orifice then removed them and blew out each one individually too. Cleaned up the pilot the best I could.
 
Could there be a clog or air lock in the line somewhere that is causing uneven flow? I purged the gas line right before it enters the unit. Wondering if there’s something that needs to work it’s way through the system
 
Is there a regulator on the LPG line before the heater? If so, it may have failed. Regulators are not fool-proof and sometimes cheap ones get installed. A failed regulator could be allowing too much static pressure to build up. You need a proper manometer and hose barbs with a tee connector to check the static and dynamic gas pressures across the gas valve. If the static pressure is too high, then the next likely culprit is a bad regulator.
 
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