Gas and Oil Home Heating Furnaces - Lennox G40UH wouldn't ignite
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mineown
08-22-07, 08:54 PM
I have a two and half years old Lennox G40UH furnace that just stopped working this morning.
When I set the thermostat to the highest temperature, I can tell that the combustion air inducer is started. However, there is no gas coming out of three gas orifices connected to the gas valve. The ignitor doesn't work either. I am pretty sure there is gas in the gas pipe connected to the furnace, because it shares a main pipe with my hot water tank, which is working normally.
If I only start up the ventilation function, the Blower can be started and I can feel cold air coming out of all air registers.
I also double-checked two diagnostic LEDs, they are all flashing slowly when the thermostat doesn't send a signal and flashing fast when the thermostat initiates a heating demand. Therefore, everything seems normal according to the LEDs.
I also double-checked all wiring from the SureLight control board, suspecting that a furnace cleaning guy might have left a few wires lose after finished a cleaning a month ago. Unfortunately it was in vain.
I also checked the fuse on the SureLight and it seems fine as well.
I am really running out of options, anyone has any idea?
Thank you very much
When I set the thermostat to the highest temperature, I can tell that the combustion air inducer is started. However, there is no gas coming out of three gas orifices connected to the gas valve. The ignitor doesn't work either. I am pretty sure there is gas in the gas pipe connected to the furnace, because it shares a main pipe with my hot water tank, which is working normally.
If I only start up the ventilation function, the Blower can be started and I can feel cold air coming out of all air registers.
I also double-checked two diagnostic LEDs, they are all flashing slowly when the thermostat doesn't send a signal and flashing fast when the thermostat initiates a heating demand. Therefore, everything seems normal according to the LEDs.
I also double-checked all wiring from the SureLight control board, suspecting that a furnace cleaning guy might have left a few wires lose after finished a cleaning a month ago. Unfortunately it was in vain.
I also checked the fuse on the SureLight and it seems fine as well.
I am really running out of options, anyone has any idea?
Thank you very much