Flameworks millivolt valve: pilot outage or burner will not come on

What is going on

Fireplace or heater with a Flameworks millivolt or 3 V gas valve: pilot will not stay lit, or the main burner will not come on.

Likely causes

• Pilot flame not covering the thermocouple/thermopile tip
• Low thermocouple or thermopile output
• Weak automatic pilot magnet
• Failed valve operator
• Too much resistance in thermostat leads

Check in this order

1. Lighting knob to PILOT, push and light, hold 2 minutes before releasing. If the pilot lights without pushing the knob, replace the valve.
2. Pilot flame should cover the upper 3/8 in. of the thermocouple/thermopile tip; adjust with the pilot screw, never with the knob.
3. Thermocouple (non-millivolt) closed-circuit output under 8 mV = replace the thermocouple. Magnet check: a good magnet stays latched for a drop of at least 5 mV from the stabilized reading, otherwise replace the valve.
4. Millivolt thermopile output should be 250-750 mV. Test A (terminals 2 & 3, thermostat closed) above 100 mV but valve not opening = replace the valve operator. Test B (1 & 3, thermostat closed) below 325 mV = clean/tighten connections, adjust pilot, else replace the thermopile. Magnet is good if it stays latched down to 120 mV or less.
5. Test C (thermostat circuit) too high = clean/tighten thermostat leads, shorten them or use heavier wire, or replace the thermostat. Max wire: 14 ga 100 ft, 16 ga 64 ft, 18 ga 40 ft, 20 ga 25 ft, 22 ga 16 ft.
6. Do not exceed 1/2 psi (14 in. w.c.) inlet. Replace any valve that has been under water or will not shut off.

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