Heater igniting, not firing on

Light a stovetop burner and watch the flame while the furnace tries to ignite. If the flame stays full, the problem is 99% a dirty orifice in the furnace, or bad/dirty burner, depending on the make and model. If the flame drops, your LP regulator is bad.

Here is more detailed information of the situation.

The heater had two problems prior to the lack of ignition. First, it would not fire every time, more like one out of three. Also, the blower would not shut off when the fire did. It would keep spinning. And perhaps it would never relight. I can't recall.

Now the heater has no flame. I turn on the the heater and set the thermostat. After an appropriate amount of time (15 seconds ish?)the blower kicks in. Then a short time later, the igniter fires with several clicking/sparking noises. There is no ignition of flame. On occasion, I here a quick whoof of a flame, but only for half a second. Once recently it stayed on for thirty seconds or so. Otherwise nothing. And the blower keeps blowing.

I am thinking there is a problem with the relay switch, but not sure if there is more going on here. So again, thanks for you help.

We find a very small LP loving spider in the gas orifice about every other year.

That outside stuff is known to freeze-up too I think...

Roy Ken

Your regulatoris bad not allowing the proper pressure

Since it is sparking I do not think it is a battery issue.. A few years ago (2011) I put together this tribble shooting chart.. If you have to ask why,, Just re-read your original post.. Not exactly the same reason.. but close.. Since I put a lot of work into figuring out my tribble.. I decided to take notes.

When the T-Stat calls for heat the control board starts the blower (1)
The blower blows closing the sail switch (2)
The control board then opens the gas valve (3) and begins sparking (4.1)
Gas Flows (5) And ignitets (4.2)
The flame heats the flame sensor (5)
The flame sensor sends .480 volts to the control board (6)
which then detects the .480 and continues operation (*)
When the T-stat says "Enough already" (RV is now warm)
The control board shuts off the gas flow (*)
and then turns off the blower after a cool down (*)

*: At nearly every step the control board is involved. IF IT IS BAD, things will not work.. I recommend replacement boards from Dinosaur boards.. When Mine went out the Dino board was less than half the price and when opened the box the quality of construction and workmanship, and then design was very clear to my trained eyes.

1: No 12 volt to furnace, blower motor shot
2: Low 12 volt, air ducts clogged, blower "obstructed" bad sail switch
3: Bad solenoid, Clogged Gas Jet
4: .1: Bad ignition circuit (high voltage) on control board. .2: Points too wide (Very common it seems)
5: These do not often fail but they can
5: Bad connection, NOTE:
5 and * Bad wire.

* applies to all steps by the way So does bad wire/connection.