Is the thermostat calling for heat? Is there 115V at the burner receptacle?
Check blower side door for seal. Repair if necessary.
Check blower for obstructions. Replace blower if necessary.
No Gas Supply
No Gas Supply
Check to see if manual supply valve to heater is ON.
Check to see if gas valve knob on heater gas control is ON.
Supply gas pressure can be checked at 1/8" NPT pressure tapping in gas supply system.
Is combination gas control opening? No manifold pressure indicates valve is closed. Gas pressure downstream of gas control can be measured by connecting a manometer to pressure tap on control. If the valve is closed, either the gas valve or the ignition module is faulty.
Burner Does Not Light
Burner Does Not Light
Is spark visible through site glass during ignition trial? If no, further electrical checks by a qualified service person are probably necessary.
Check to see if gas lines were properly purged of air.
Check inlet and outlet gas pressure during ignition period.
Check for orifice and air plate obstruction.
Burner Does Not Stay Lit
Burner Does Not Stay Lit
Check ground wire continuity.
Check insulation on the igniter leads.
Measure flame signal current; it should be above 0.8 micro amps DC.
