Raypak 406 flame out troubleshooting help?

CharlieEB

New member
Oct 19, 2019
3
San Jose, CA 95111, US
Looking for advice on servicing my heater. It's flaming out of the combustion chamber right under the rollout switch. When I took over the unit was full of tree debris, I took the covers off and extensively cleaned it out. I also replaced the thermostat housing on the header as it was leaking. The unit is a bit dirty from cleaning neglect but inside it looks unused beside the flame out - The combustion chamber has zero soot - I've shined a light up and down it and looks very clean (shiny burners and very clean firebox). After cleaning out all the debris it still flames out. It seems the next step is the removal of the gas hardline and pulling out the burner tray to inspect everything. I'm not sure I can do this without also unhooking the exchange plumbing and moving the entire unit. Wondering if anyone has suggestions of things to try before I disassemble further? (or have someone else do this for me).

This video isn't the greatest example - it usually lights normally then starts flaming out a min or two in. This video was taken on the 3rd attempt.
 

CharlieEB

New member
Oct 19, 2019
3
San Jose, CA 95111, US
Ok made a 2nd video showing some more of the unit - It's not as pristine as I thought but here is a video showing inside the combustion chamber and a few of the burner tubes. Should I try running something down the burners like a coat hanger?

 

CharlieEB

New member
Oct 19, 2019
3
San Jose, CA 95111, US
Update: I ran a coat hanger through all the burner tubes - spiders came out - web came out - not a huge volume but enough to warrant giving it a try. It started up and acted normal!! let it run 5 mins before I shut it down. Started it again and it is still working without flameout (timer says 45 mins so far)! Any opinions on the flame color? I get the impression from the PO's pool guy this was never used.

 
Last edited:

swamprat69

Well-known member
Mar 30, 2019
82
Las Vegas, NV
Did see some yellow tipping on flames which is an indication of incomplete combustion/lack of sufficient oxygen and can cause sooting. If you had spiders in the burners you should clean the burners thoroughly by taking them off the manifold and using a brush inside the burner and a wire brush to clean the slots on top of the burner then blowing out the burner from the inside out with air or CO2. If your spiders mated you may have baby spiders small enough to get into the burner orifices/ gas manifold. These can be cleaned out with a pipe cleaner or carburetor cleaning brush when the burners are off the manifold. Here are some tools that may be applicable depending on the inside diameter of the burners and are available on Amazon.

Forney 70487 Tube Brush, Nylon with Wire Loop Handle, 15-1/2-Inch-by-1-1/4-Inch

Twisted Wire Stem Gas Grill Venturi Brush
by Brushtech... varying diameters


AUTOLA Carburetors Carbon Dirt Jet Remove Cleaner, 13 Cleaning Wires Set + 10 Cleaning Needles + 5 Nylon Brushes Tool Kit for Welder Carb Chainsaw Spray Guns Torch Tips Firing Hole Stove Burner Holes...although pipe cleaners can usually get the job done
 

swamprat69

Well-known member
Mar 30, 2019
82
Las Vegas, NV
Should be able to remove the whole burner tray by shutting off the gas supply, opening the union on the gas supply between the shut off and the gas valve/manifold and removing the gas piping at a connection point between the downstream side of the union and the piping to the gas valve inside of the heater cabinet. May have to mark and remove wires at gas valve and bonding wire on left side of burner tray, then screws on either side of burner tray. When reassembling gas piping use pipe dope/teflon tape on the threaded connection that you took apart inside the heater cabinet and leak check with soap bubble solution with the gas shut off open at that connection. Let me know if you need any further help or have any other questions.