SIT 820 Nova millivolt valve: pilot will not stay lit

What is going on

The pilot lights while the knob is held but goes out when released, or drops out later.

Likely causes

• Wrong inlet pressure
• Pilot flame too small or not on the thermocouple/thermopile
• Thermocouple or thermopile not fully seated, dirty or failed
• Failed safety magnet in the valve
• Wrong or blocked pilot orifice

Check in this order

1. Relight and hold the knob in for 30 seconds before releasing.
2. Check the thermocouple and thermo-generator are fully inserted in the pilot; thermocouple tight in the valve = hand tight plus 1/4 turn with a wrench. Clean the tips (upper 3/8 in.) with very fine emery cloth.
3. Millivolt Plus open-circuit thermocouple voltage should be 18-28 mV; under 14 mV = replace the thermocouple.
4. Safety magnet (mV Plus) hold the pilot button, reconnect the thermocouple, measure between the solder button on the magnet and the valve body. Above 6 mV (vented) or 8.5 mV (unvented) and the magnet will not hold = replace the valve. Closed-circuit reading equal to open-circuit = open coil, replace the valve.
5. Millivolt system remove the operator wires and measure TPTH to TP; above 110 mV and the magnet will not hold = replace the valve.
6. Replace a blocked or wrong pilot orifice with the exact one for the appliance and gas type.

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