Pilot model appliances

[DaveVA78Chieftain]

When lighting the pilot for a pilot model propane device (fridge, water heater, furnace), it can take forever to clear the air out of the line through the hair size pilot light hole.  This is a real pain after changing a tank or the system has been shut down for the winter.   Make sure you get as much air out of the line first by lighting a stove top burner.  Then just have a whole lot of patience lighting the other pilot lights in order to clear the air out of the line.  The pilot orifice does get clogged up.  Only use compressed air to clean it out.  Sticking anything into it can make it bigger and result in to large a pilot flame which can create other problems.

Pilot model devices use a thermocouple to generate a small voltage signal to the gas valve.  This voltage is applied to a magnet inside the gas valve.  The magnet must be energized in order for gas to flow though the valve.  The only overide is the pilot lighting mode which allows pilot gas to flow.  Once the themocouple is heated and generating voltage then it keeps the magnet energized.  With the thermocouple removed you can use the millivolt setting of a volt meter to measure the voltage generated when the thermocouple is heated with a lighter.  Connect one meter lead to the thermocouple wire and the other lead to the button that goes inside the gas valve.  Should get a minimum of 12 millivolts when heated.  You can measure continuity of the magnet inside of the gas valve.  Connect one meter lead to the valve body and the other to the connection inside the hole where the thermocouple is attached.  Atwood water heater pilot model gas valves have a built in Emegency Cutoff (ECO) feature built into them.  If the temperature in the tank goes above 190 for any reason the ECO will open.  Bad news is it's only a one shot deal.  If the ECO opens then the gas valve has to be replaced.

Dave