The unit is a 12 year old Bryant Plus 80 376cav downdraft installation. Within the last 18 months the mainboard (would not call for blower), draft inducer fan assembly (squealing), and hot surface ignitor (not needed but replaced anyways) were replaced by a technician. Filter replaced as it should be. The wired thermostat is a digital programmable Honeywell (about 5-7 years old).
Typically, I leave the thermostat on, but below a household temperature that would call for the furnace. When I need to elevate the temperature, the unit goes thru its cycle properly on the first attempt and runs on, off and back on as it should to maintain a setting. Everything works as it should for days.
Now here is the issue. If I turn off the thermostat (or if the thermostat setting has been below a heat call for over say, 24 hours) then come back a day later and turn it back on the unit will go through the start up - draft inducer motor running fine, hot surface ignitor glows and looks as it should, however the gas is not "called" for ignition. Cycle stops. No code. A minute or two later, it attempts the start up cycle. No go again, which may happen at least four times. No code. Fifth time, the cycle - gas, blower on and the furnace will work as it should, cycling on and off to maintain thermostat setting.
In summary, this happens typically after thermostat has been turned off (or not call because of low setting for extended period). Gas is not called for. Cycle repeats multiple times until successful cycle. No led status codes. Light continuous on.
No code baffles me. I also inspected the area around the draft inducer motor for any air breaches. When the inducer assembly was replaced, the technician replaced the motor, as well as the fan (squirrel cage) and a new gasket set. No shortcuts there. No reason to suspect the hot surface ignitor which looks good. All wires to mainboard look secure. Have not tried component test yet.
What else might be checked here before I call my guy back in? Afraid it will work as it should and incur a service call.