Gas and Oil Home Heating Furnaces - old floor furnace burner not igniting

I need help I live in Southern California and have a old floor furnace of unknown brand. The house was built I believe in the 50's It is a gravity furnace I think It does not have blower have digital thermostat connected for past 5 years. Pilot light works blue flame with orange tip. However the burner will not ignite I've gotten it to light by placing 1.5 volt battery across the only 2 thermostat wires. Voltage across thermostat wires appears to be 150 mV checked with digital meter. I've checked thermostat with meter infinity with thermo off and zero ohms with it on I'm presently very confused any help would be appreciated.:wall:

You need to remove and disassemble the pilot burner and clean the pilot burner and pilot orifice.

More than likely a dirty pilot burner is preventing the pilot generator from getting hot enough to generate enough power to operate the main burner gas valve reliably.


After you get things working, take the cover off the top of the floor furnace and check out all the dirt and crap that's accumulated over the decades. Usually there is a set of baffles that can be removed and cleaned, and which also provides easy access to clean the rest of the area.

Clean that out with a vacuum cleaner and reassemble.

You should also inspect then vent pipe for holes and rust, then pull out the vent pipe so the chimney can be inspected for accumulations of sand and debris that could block the combustion gasses from going up the chimney.

Thanks I'll give it a look