Raypak 406A Burner won't fire but do get pilot

moconnor5557

Member
Aug 31, 2020
5
Buffalo, NY
Burner won't fire... Corrective action taken:
  • All safety switches operate, I disconnected them and jumpered the wires getting an error when open and no error when jumped
  • roll over switch works, error when open, no error when jumped or connected.
  • Spark at pilot and it lights
  • fuse on main board good
  • Changed the regulator
  • Cleaned the burner and pilot
  • I get 26.2 volts in diagnostics
  • Pilot tube cleaned
  • When I disconnect the Sensor Adapter Digital Electronic from the board it senses and give me an error, not certain how to further test this sensor?
  • Thoughts...guessing at this point it is the board...hoping for some validation...thanks
 
Last edited:

swamprat69

Well-known member
Mar 30, 2019
326
Las Vegas, NV
Don't know why your question hasn't been addressed yet? It sound as if your pilot flame is not proving it is there. If you have a strong blue pilot flame, here is some advice given in a similar situation. Not all info may apply, but pay close attention to cleaning the pilot assembly and ALL grounding points to bare metal.
Here is the manual for your heater: http://cdn.globalimageserver.com/FetchDocument.aspx?ID=c404f1c5-ac50-4209-9457-56246d010b20. Look at page 34. If you do not have a millivolt system look at the bottom pilot assy. . Start cleaning by turning off heater and and gas supply shut off. Remove pilot bracket screw and green ground wire at bottom right of burner manifold bracket. Remove pilot tubing at gas valve. Remove pilot assy. and pilot tubing as one piece. Clean all metal pieces where pilot assy. bracket was attached to the burner manifold bracket including the screw and the metal termination of the green wire with a small stainless steel wire brush and/or small diamond file (available at Harbor Freight). On the pilot assy itself (page 34) you need to clean the underside of the pilot hood (above the pilot tubing attachment) with a dental pick (Harbor Freight) until the metal is clean. Also gently clean the spark rod with a small diamond file or steel wool all the way around to get bare metal, being careful to support the ceramic insulator so that it doesn't crack. Clean the underside of the ground hood ( opposite the pilot hood with the 2 extended tabs on the outside edges) with small stainless brush and/or diamond file to get to bare metal. Clean any screws and metal points of attachment at the grounding hood side of the pilot assy. at the pilot bracket and burner frame that the pilot bracket is attached to. Reassemble in reverse order making sure to tighten the pilot tubing to the gas valve. Turn on gas shut off and power to heater. Put a small amount of dawn dish detergent mixed with a little water on the pilot tubing attachment at the gas valve. Fire up heater. Check for any bubbles at pilot tubing attachment at gas valve (indication of a leak).
 

moconnor5557

Member
Aug 31, 2020
5
Buffalo, NY
Thank you for the reply. I also tried that, buffed all the pieces...with no luck.

Questions:
  1. Is there a fan or blower in the 406A? If yes, does it need to be blowing in order for the burner to fire?

Next steps:
  1. I did order a new pilot assembly which I will try when it arrives.
  2. I will clean the base to insure a good ground. I am wondering as the base is a bit rusty if it isn't making good ground contact and therefore causing the problem. However I do get the pilot to fire with 24v so not sure if it is the ground? Can I take the PV and put it on the MV then try to light it manually? If that can be done it would tell if the 24volt relay is working...
  3. If all else fails I guess I will need to change the board. I am wondering if one the relay on the main board for the MV is shot??
I appreciate the assistance. Thank you!
 

ajw22

Gold Supporter
TFP Guide
Jul 21, 2013
19,798
Northern NJ
Raypak 406A Digital heater does not use an induced draft blower.

What does the Flame Strength indicator show on the Service Menu?

Service Menu and Fault History
To access the Service Menu and fault history, press the MODE and UP buttons simultaneously for 3 to 5 seconds. The heater will continue to operate normally while in the Service Menu. The first screen displayed is the Flame Strength indicator, which indicates the pilot flame current using a bar graph and numerical display. A signal of less than 4 indicates a weak flame signal and may require service. Refer to Section 5 Troubleshooting in the manual for possible causes and corrections.

Press the DOWN button. The Supply Voltage screen indicates the voltage supplied to the control board. Normal readings range from 24 to 29 volts.

Press the DOWN button. The Run Time indicates the total hours of operation for the pool heater, as measured by the amount of time that the main gas valve has been powered. The Cycle count indicates the number of on/off cycles of the heater, as measured by the number of times the pilot valve has been powered.

Press the DOWN button. The Fault History can display up to ten faults in memory. The order of the faults begins with “Fault Last,” which is the most recent fault, and proceeds through ten most recent messages in chronological order. The second line of the display shows the fault message. If there are no faults in the history buffer, the second line reads “All Faults Clear.”
 

moconnor5557

Member
Aug 31, 2020
5
Buffalo, NY
Flame Strength is "0".

Voltage is 26.2

I get the voltage to the PV post on the Gas Valve and the pilot does light...I do not get 24 v to the MV post which to me means that one of the safety switches is tripped or the main board. All switches seem to be fine.

Questions:
  1. Is there a fan or blower in the 406A? If yes, does it need to be blowing in order for the burner to fire?
 

moconnor5557

Member
Aug 31, 2020
5
Buffalo, NY
Thanks - cleaned everything, still didn't work. Ordered a new pilot assembly, installed it and it fired right up...

Now after a bit I get "High Limit 2 Fault" my thermostat's rubber gasket looks out of round...I did test the thermostat in hot water and it appears to work. Was thinking of changing the thermostat and washer...thoughts?