Here are my observations on this 8-year-old 95% Goodman furnace: (These are all intermittent occurrences)
- Ignition sequence proceeds to igniter on, burners do not light, igniter off. 1a. Ignition sequence proceeds to igniter on, gas valve can be heard and felt opening, burners do not light, igniter off. (if these failed ignition attempts occur 3 times, the system locks out with an E0 error code)
- Ignition sequence proceeds to igniter on, burners light but with some blowback or flameout.
- Following a lock out, removing the black drain hose from its fitting in the drain pan behind the inducer may allow a few ounces of condensate to flow out, but this does not occur consistently with every lock out. (Residual condensate here likely prevents the inducer from producing sufficient draft to allow the ignition sequence to continue).
- Furnace may shut off before reaching the set temperature. Because the thermostat is still calling for heat, the ignition sequence begins again, but under these circumstances, a lock out always seems to occur.
- The only error code seen is E0 (lockout due to excessive ignition failures). Note: Ventilation plumbing has recently been redone using a concentric vent system. I am very confident that there is no issue with the exhaust venting. Note: The condensate pump is functioning properly and there is no water leaking out onto the floor. Note: There have been no elevated CO or explosive gas warnings signaled by a new Kidde Nighthawk combination detector next to the furnace.