Raypak 406a Main Ignition Failure Heater keeps cycling

gatorson

Member
Sep 18, 2018
10
Fort Lauderdale
Hello everyone, I have a natural gas 406a Raypak/Rheem heater continuously cycling after starting up. The first time the heater sparks and calls for heat the heater will stay lit for sometimes a couple minutes. After this time period the burners will go out, but the pilot will stay lit, "spark" will display on the lcd and the burners will temporarily light again, then go out. When the burners relight it is not usually log enough for the lcd to even read "heating". Rinse and repeat. After this "Main Ignition Failure" will display on the LCD. I've replaced the Unitherm governor previously because of condensation problems. Sometimes after 30 minutes of cycling the heater will actually stay lit for 2-3 minutes then go back to cycling. I'm prone to thinking the unit needs a new board, but I want to rule out everything else first. The board looks at a glance to be good and no frogs/lizards underneath the board either. My unit is about 14 years old based on the serial. I've uploaded a video of what is occurring as well. If anyone has any advice it is greatly appreciated.

Could this be a pilot issue? I hear the audible click of the gas valve opening up and the pilot spark clicking as well.

 
Last edited:

JamesW

TFP Expert
Mar 2, 2011
16,493
Try cleaning the ground wire connections. The flame Rectification signal travels through the ground back to the control board. A bad ground will prevent the signal from reaching the control board.

Some heaters show Flame strength, which is a reading of the flame Rectification microamp signal. If you have a flame strength reading, see what that shows.

If the flame strength is not shown in the display, you can check it at the control board where it says flame current FC+ and FC-. The reading should be between 1 and 10 microamps or 1 and 10 volts dc.

Note that the heater looks pretty old. If the bottom is rusting out or if there are other signs of serious problems, you might be due for a new heater.

Consult a qualified gas contractor if you have any concerns about the safety of the heater.
 

skimmerswimmer

Well-known member
Jul 30, 2013
334
Long Island, NY
I have the mV version of the Raypak, so no control board. The only time I see a fully fired up Raypak stop like that is when one of the items in the safety circuit stops conducting, and the heater turns off thinking there is a safety issue. My issue was a bad thermostat. Check your connections to all switches and safety components make sure the crimp terminals are good on all the wiring. The board appears to be detecting an issue somewhere and is shutting down the main burner. Could be a bad board, but it's hard to say. In my case, I can bypass everything with a jumper to narrow down the bad component.
 

gatorson

Member
Sep 18, 2018
10
Fort Lauderdale
Try cleaning the ground wire connections. The flame Rectification signal travels through the ground back to the control board. A bad ground will prevent the signal from reaching the control board.

Some heaters show Flame strength, which is a reading of the flame Rectification microamp signal. If you have a flame strength reading, see what that shows.

If the flame strength is not shown in the display, you can check it at the control board where it says flame current FC+ and FC-. The reading should be between 1 and 10 microamps or 1 and 10 volts dc.

Note that the heater looks pretty old. If the bottom is rusting out or if there are other signs of serious problems, you might be due for a new heater.

Consult a qualified gas contractor if you have any concerns about the safety of the heater.
My flame strength shows 6 "Good" when lit and my error codes 1 thru 10 all read "Main Ignition Failure". I agree that the heater will need to be replaced at some point but am hoping to get a little longer out of it for $100 vs $2k.
 

JamesW

TFP Expert
Mar 2, 2011
16,493
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 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.
FAULT HISTORY
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.”
 
Last edited:

gatorson

Member
Sep 18, 2018
10
Fort Lauderdale
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 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.
FAULT HISTORY
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.”
Supply Voltage is 24V
Run time ~700
Cycle count ~2200
All faults 1-10 read "Main Ignition Failure"
 

JamesW

TFP Expert
Mar 2, 2011
16,493
I think that it's losing the flame rectification microamp signal from the pilot for some reason. Hard to tell why.

Make sure that the gas pressure is good, clean the ground connections, check the pilot for good flame.
 

swamprat69

Well-known member
Mar 30, 2019
69
Las Vegas, NV
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 all the way around to get bare metal. 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. to the pilot bracket. 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).
 
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ps0303

TFP Expert
In The Industry
Jul 6, 2011
4,020
FL
In watching your video, that unit is shot and needs to be replaced. Seeing you have the burner tray propped up with a cement brick and the amount of rust on the unit it is done for. Putting any money into it is a waste if you ask me. I would also venture to say that possibly the pilot assembly is shorting out as it's all rusted as well. You might also have little to no air flow thru the heat exchanger as well. If I were called to look at this, I would tag it and disconnect the gas.

So please take my advice and replace the heater.
 

skimmerswimmer

Well-known member
Jul 30, 2013
334
Long Island, NY
In watching your video, that unit is shot and needs to be replaced. Seeing you have the burner tray propped up with a cement brick and the amount of rust on the unit it is done for. Putting any money into it is a waste if you ask me. I would also venture to say that possibly the pilot assembly is shorting out as it's all rusted as well. You might also have little to no air flow thru the heat exchanger as well. If I were called to look at this, I would tag it and disconnect the gas.

So please take my advice and replace the heater.
This is what I did when my original Raypak heater was about the same age. 14 years is a good run for an outdoor pool heater. Start fresh with a new unit and cut your losses.
 

gatorson

Member
Sep 18, 2018
10
Fort Lauderdale
I agree that the heater has had a pretty good 14 year run. I did replace the pilot / pilot tubing / and pilot bracket since these are relatively cheap parts to fix and to my surprise the heater works again. I think the pilot was shorting out or had a bad ground since the pilot bracket was full of rust. I am considering replacing the burner tray. I took apart the heat exchanger and it looked surprisingly good - no rust or clogs. Does anyone know if the burner tray is difficult to replace in this model? I would also replace the rusted floor with new steel.
 

ps0303

TFP Expert
In The Industry
Jul 6, 2011
4,020
FL
This is more than just a floor pan replacement. The burner tray is rotting thus why it is propped up with a brick.

I'm all for keeping something running as long as you can but this unit is now past the point of no return.
 
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