Perhaps it is the control board or the stat that is faulty.
Do you have a volt meter?
Actually, I do...but must admit, I'm not that comfortable in how to use it. It's a "50/60HZ Voltage tester GVT-82".
As for the thermostat, it's brand new since that was the very first thing I'd tried to change when the furnace started going cold (sorry I forgot to mention that).
When the furnace does not start does the LED on the control board flash at all?
I'm sorry, are you talking about the circuit board that is just above the blower motor (behind the bottom panel) or are you talking about the two LED lights on the Honeywell Ignition control module?
The one above the motor where all the thermostat wires are attached.
I am an old Lennox Engineer. Most of the time on these Whisperheat units it is the igniter. Everytime I change one it is a diffferent manufacturer. Does the furnace lite now? Tell me what it doing now. Also do you need an install manual with all the trouble shooting procedures. So you can follow.
Thanks for your reply, Rus. As of right now, the only time the furnace will light is when I turn the gas and power off, then put the gas back on again (at the regulator) and turn the power back on. The furnace will then light the pilot, seconds later you hear some clicks, and seconds later the burner ignites...but then that's it. It does not come on again by itself when the temperature falls below the desired setting on my thermostat.
I guess the reason I'm wondering if it could be a faulty new ignitor module is that when I went to buy it at the appliance parts store, the box was already open when the man brought it to the counter. Just seemed "odd", especially now because it does work initially, but like I said, only the one time.
As for the install manual, the Honeywell 30W33 did come with a 4 page installation booklet, but there are no troubleshooting methods in it.
go to www.cozyparts.com/Lennox-Parts/forum/Lennox/furnaces/G20_01_2003.pdf
for complete manual. This way we will be on same page. It is leaning toward igniter. Check trouble shooting chart in back of manual. Get back if you need help.