| Problem |
Possible Cause |
Solution |
| Pilot light will not light at all. |
Spiders or mud wasps plugging pilot tube. |
Clean out blockage in pilot tube with a wire or pipe cleaner. |
| |
Gas not turned on or air in line. |
Have supply checked by gas company. |
| Pilot light goes out when trying to start unit. |
Weak pilot. |
Adjust pilot length with screw on gas valve marked pilot adjustment. |
| |
Thermocouple bad. |
Replace thermocouple. |
| |
Air in gas line. |
If new insulation have gas lines bled of trapped air. |
| Thermostat doesn't start heater |
Thermostat bad. |
Short wires on thermostat together if this works replace thermostat. |
| |
Wires defective or damaged. |
If above doesn't work short wires at the gas valve together, if this works replace wires. |
| |
Defective control valve. |
If above doesn't work replace gas valve. |
| |
Low pilot flame |
adjust pilot flame longer |
| Pilot stays lit but main burner will not light |
Gas valve not in correct position. |
Turn knob to on position. |
| |
Blocked burner orifice. |
Clean or replace. |
| |
Loose wire or improperly wired. |
Check all wiring for clean connections and damaged wire. |
| |
Gas pressure low. |
Have supply checked by gas company. |
| |
Pilot out of adjustment. |
Adjust the pilot light length longer using screw on gas valve marked pilot adj. |
| Burner flash back (burning inside venturi) |
High gas pressure. |
Adjust pressure. |
| |
Defective burner (caused by cracked burner or gasket material failing). |
Replace burner. |
| Burner sooting |
Dirty burner orifice. |
Clean. |
| |
Damaged burner orifice. |
Replace |
| |
Damaged or misaligned manifold. |
Replace. |
| |
Dirty burner. |
Clean. |
| |
Gas pressure incorrect. |
Adjust. |
