It runs fine for the approximately 15 minute heat cycle. It appears as though it happens as the thermostat is satisfied and the gas valve shuts off. The vibration is heard upstairs and throughout the house. The furnace runs after the vibration for a couple minutes. There is no obvious location when at the furnace. Should I remove the lower panels to be closer to the apparent noise (with buttons pushed to keep the unit operating?).Thermostat wiring issue - gas valve solenoid chatter?
The furnace is a 90% Arcoair 6 yrs. old and this is the second year with this issue. I originally thought it was a shorted sump pump electrical issue as it sounded originally like an arcing when the sump pump came on (from upstairs). New sump pump and continued noise and further investigating proves otherwise.