Heater won’t ignite

[RJ Schubert]

Hi all. Thanks for the help. I have a 2018 Thor Quantum RQ29. I have gas to the fridge, stove and water heater but the furnace won’t light. I have 13.5 volts at the inverter and am plugged into shore power. I took the furnace cover off and it is clean. I hit the reset button and tried turning it off and back on.

The blower will come on for about 5 seconds then shut off. I don’t know if this is related but my Atwood CO/propane sensor has a red light on the propane side. All battery connections were cleaned and tightened.

All breakers are set.

Any help on the furnace would be appreciated.

RJ

 

[MJC68]

Might be a bad sail switch or the mother board has gone bad.
A 2 pack of new sail switches is under $15 on Amazoom
There had been some issues with the board getting wet.
If the board is bad the recommended replacement is made by Dinosaur.

 

[16ACE27]

As mentioned above, if it never starts sparking to light the flame then the sail switch is the prime suspect.

 

[RJ Schubert]

Thank you guys. I’ll order the sail switch and change that out. I’ll let you know if that’s the answer.

 

[HMCSW]

Hi all. Thanks for the help. I have a 2018 Thor Quantum RQ29. I have gas to the fridge, stove and water heater but the furnace won’t light. I have 13.5 volts at the inverter and am plugged into shore power. I took the furnace cover off and it is clean. I hit the reset button and tried turning it off and back on.

The blower will come on for about 5 seconds then shut off. I don’t know if this is related but my Atwood CO/propane sensor has a red light on the propane side. All battery connections were cleaned and tightened.

All breakers are set.

Any help on the furnace would be appreciated.

RJ

Can you hear the ignitor trying to light? Do you have dogs? If you do have dogs the sail switch might just have hair keeping it from working. Could just need cleaned.

 

[RJ Schubert]

The igniter isn’t trying to light. I did order a pair of sail switches and will check the old one when I take it out. If it just needs cleaning then I’ll have an extra pair for the next time. I’ll let you know. Thanks for the suggestion.

 

[Jimbo56]

I’d take a close look at the igniter. If the sail switch is bad it’ll still spark. Sounds to me as yours isn’t sparking. To me that’s an indicator of a bad igniter or a bad control board. From what I’ve read on this forum, a faulty sail switch will ignite and then shut down in a few seconds.

 

[RJ Schubert]

Thank you Jimbo. I’ll check and change out the sail switch first. No, the igniter wasn’t clicking. If the sail switch isn’t the issue then I’ll check the igniter next.

 

[16ACE27]

I’d take a close look at the igniter. If the sail switch is bad it’ll still spark. Sounds to me as yours isn’t sparking. To me that’s an indicator of a bad igniter or a bad control board. From what I’ve read on this forum, a faulty sail switch will ignite and then shut down in a few seconds.

The ignitor will not attempt to light the flames if it does not get a positive signal from the sail switch that their is adequate air flow from the fan. That would be a recipe for disaster.

From the Atwood Service Manual:

Sequence of Operation

The ON/OFF switch allows power to pass to the circuit breaker
and the thermostat.

The thermostat controls the operating circuit to the furnace by
reacting to room temperature. When room temperature is below
the thermostat set point, the contact closes to allow current to flow
to the relay (relay can be either external or part of the ignition
control board).

The circuit breaker limits amperage draw of motor.

The relay allow current to pass to the motor by closing a switch
within the relay. Voltage from the thermostat activates the relay to
turn the fan on. This takes 1-25 seconds (on units with relay on
the ignition control board there is only a 1-2 second delay).

Current flows to the motor to operate the blower. One end of the
motor shaft is for the circulating air wheel and the other side is for
the combustion air wheel.

Circulating air blows against the sail switch and closes the
contacts, completing the circuit. The sail switch is a safety device
that insures air flow before ignition.

 

[RJ Schubert]

Thanks again Ace. I think that you nailed it. My new sail switches should come today sometime.

 

[RJ Schubert]

Well, I put in a new sail switch this morning. Blower comes on but no igniter clicking. I’ll check that next.

 

[RJ Schubert]

Could it also be the high limit switch?

 

[HMCSW]

Well, I put in a new sail switch this morning. Blower comes on but no igniter clicking. I’ll check that next.

I just went through the same. There was a switch valve $36 but had to remove the blower assembly to get to it. Fortunately mine was covered by warranty. They replaced a few parts and the main board. The main board has issues with getting wet.

 

[Jimbo56]

Just a thought. Are the wires to the igniter tight?

 

[RJ Schubert]

I will check that.

 

[RJ Schubert]

All wires seem firm. I used my multimeter on the high limit switch (I think it right above the furnace outlet) and it read 0.00 on ohms.

I believe that my Atwood furnace is PN 32830. Can you verify that that is correct?

If so I can order a new board and high limit switch. We’re heading out on a trip in a week or so and I want to make sure the furnace is working.

Thanks all.

 

[16ACE27]

All wires seem firm. I used my multimeter on the high limit switch (I think it right above the furnace outlet) and it read 0.00 on ohms.

I believe that my Atwood furnace is PN 32830. Can you verify that that is correct?

If so I can order a new board and high limit switch. We’re heading out on a trip in a week or so and I want to make sure the furnace is working.

Thanks all.

History says it's the Atwood circuit board. Get a Dinosaur board replacement on Amazon.

 

[RJ Schubert]

Thanks Ted. Am I correct that the Atwood furnace PN is 32830? Do I get the small universal igniter board?

 

[Trophy1200]

Not the dinosaur board, but this is what I used for my furnace.



Price is in Canadian dollars.

 

[16ACE27]

Thanks Ted. Am I correct that the Atwood furnace PN is 32830? Do I get the small universal igniter board?

This should be the correct board:

https://www.amazon.com/gp/product/B009XU7H8Q

You can check on Dinosaur's website or even give them a call to verify - they are very helpful.