Lp & heat

LP system checks

Regulator pressure: about 11 inches of water column (in W.C.) at the appliances, with the appliances running. Use a manometer. 11 in W.C. is about 0.4 psi.

Leaks: soap solution or an electronic leak detector. Bubbles or an alarm means a leak. Fix it before anything else. Test again after any LP work.

No open flames or sparks while checking

Manometer reading with appliances on, at 11 in W.C.

Soap test on every fitting touched

LP and CO detectors tested, date stamps checked

Furnace: how it runs

Thermostat calls for heat (12V). Control board starts the blower. The sail switch or pressure switch proves airflow. The igniter lights (spark or hot surface). The gas valve opens. The flame sensor proves the flame. The furnace runs until the thermostat is satisfied.

Furnace: where it usually stops

Low 12V (under about 11 V) causes odd starts or lockout. Blower or sail switch stuck or dirty. Blocked intake or exhaust. Weak igniter or bad electrode gap. Dirty flame sensor. Empty LP or a regulator problem. Failed control board or thermostat.

Check 12V at the board WHILE the blower runs. Many furnace calls are a weak battery or a bad ground.

Tank water heater

Gas direct spark: needs 12V to the board, LP, and a good spark. Electric element: a typical 1440 W element draws about 12 A at 120 V. Check the thermostat and the high-limit reset.

Steel tanks have an anode rod. Aluminum tanks do not. For tankless heaters see TANKLESS: START FIRST.

Detectors

LP and CO alarms have a date stamp. Replace them when they expire, usually 5 to 7 years. Test them with the test button, not with an open flame.

If you smell LP: no switches, no flames, no sparks. Shut off the tank valve, ventilate, and get everyone out.