Gas and Oil Home Heating Furnaces - Dayton Gas garage heater wont fire

I have a 2 year old Dayton Tubular Gas Fired Propeller Unit Heater, 30K BTU, in my garage that wont start. Thermostat calls for heat. Drafter motor comes on. Igniter glow plug lights up but no gas. I have bled the gas line. The Hi limit switch and Flame rollout switch have continuity through them. The drafter pressure switch is working ok. I'm not sure of the operation of the pilot burner igniter device. There are three wires going to this area which is diffiult to see. I assume two wires are supplying voltage to light it up, but what is third wire for. Is there a flame sensor attached to it? What am I missing? There is a small diameter tube coming from the gas valve up to this area. Does this supply gas for a pilot? If so, why do you need a pilot if you have an electric igniter? I'm an old school Electronic Tech and can read schematics, but I just don't have any experience in this area. Can someone please help. I wouldn't think that the gas valve would be bad on such a new unit. I'ts not used that much. Thanks for your help.

not sure about your unit. often dayton products are made by someone else like DESA international. is there a fuel filter ? in the construction type heaters if the fuel is not supplied and the unit does not ignite a flame sensor kills the system. good luck :thumbup:

Sorry, maybe I wasn't clear. This is an LP Gas fired heater/furnace. It hangs from the ceiling and is 30,000 BTU. Never heard of filtering LP or Natural gas. Still need some help. It is a model 4LX41 and is using a Honeywell SV9540 Gas Valve Module. Thanks

are you getting power to the gas valve and if so can you tell if it is opening ?
sorry i can't be much help on this :thumbup:

Have you tried taking reading at the gas valve to see if you are getting 24 volts to it while the ignitor glows and shuts off?

If you are getting 24 volts to the gas valve, then make sure the knob on the valve itself is turned ON. I have had that happen people says the gas line is on, but the main valve is not

Drafter motor comes on. Igniter glow plug lights up but no gas.You are almost there.

I have bled the gas line.Not necessary. But it is important to know that there is pressure at the furnace.



The Hi limit switch and Flame rollout switch have continuity through them.
That is pretty much given or else the drafter-inducer wouldn't run.


I'm not sure of the operation of the pilot burner igniter device.Did you not say it is glowing?


what is third wire for.What colors are the wires? A sensor takes usually takes two wires.


There is a small diameter tube coming from the gas valve up to this area. Does this supply gas for a pilot?

Is it aluminum?



If so, why do you need a pilot if you have an electric igniter?To make sure there is a real fire before turning on the main.



I wouldn't think that the gas valve would be bad on such a new unit. Can't rule it out based on age alone. You can try to open the valve by jumpering from the transformer. If it clacks, it is probably good.

You have a Honeywell Smartvalve it appears. The hot surface igniter lights the pilot and it heats the flame rod which sends signal to open valve..Make sure there is pilot gas coming thru pilot by lighting pilot manually. May be dirty pilot..spider nest type problem