A115_F: One-hour Lockout: Gas Valve Stuck Closed
Status
This is a 1-hour lockout due to a critical fault and should rarely (if ever) be seen in the field.
Description
The gas valve relay (low and/or high) is welded shut causing gas valve to be energized when it should not. This causes the control to be locked out for an hour.
Expected Operation
If a gas valve relay is welded shut, an appropriate alarm "A225_F Internal Fault: Gas Vlv 1 Rly Welded Shut" and/or "A227_F Internal Fault: Gas Vlv 2 Rly Welded Shut" will be set, all heating operation shall cease, inducer and blower will run at the highest heat speed.
Once the condition is no longer present, the furnace shall clear "A225_F Internal Fault: Gas Vlv 1 Rly Welded Shut” and/or "A227_F Internal Fault: Gas Vlv 2 Rly Welded Shut" alarm, complete the inducer post-purge and the user set heat blower off delay. The control shall then proceed to a one-hour “soft” lockout with the alarm "A115_F One-hour Lockout: Gas Valve Stuck Closed" declared throughout the duration. Upon completion of the lockout, IFC shall clear alarm "A115_F One-hour Lockout: Gas Valve Stuck Closed". UL safety alarm "A126_F Flame not Sensed with Gas Valve On - UL" is also set during the process and it shall remain logged until power is cycled to the unit or a clear alarms command is used to clear the fault.
Cause
Faulty furnace control - relay shut closed
Solution
Replace furnace control (IFC).
