The closed circuit test will tell you the voltage drop across the main operator coil. With the switch or thermostat closed, place your meter leads on the TH and TP terminals and measure your drop in mVDC.

To ensure a smooth ignition, when the valve first opens after turning on the main burner, no more than four (4) seconds should expire before the burner has completely lit off. Although problems with delayed ignition are most likely to occur with propane (because it is heavier than air), it can still affect natural gas appliances.

Trouble Shooting Main Burner Outage on a Gas Fireplace or Stove

1. Ensure that main burner goes out on its own and pilot light remains lit. If pilot goes out as well, refer to 'Pilot Flame Outage'.

1. Check if pilot flame goes out on its own or when main burner is on.

As with the thermocouple, the open circuit test will tell us the potential output of the thermopile. While most thermopiles are designed to produce up to 750 mVDC, a minimum reading of 325 mVDC open circuit is generally acceptable as long as the switch is located close to the appliance and connected with properly sized wire.