SIT 820 Nova millivolt valve: pilot will not light

What is going on

Standing-pilot fireplace with an SIT 820 Nova millivolt valve: no pilot.

Likely causes

• Air in the gas line
• Wrong inlet pressure
• No spark: piezo wire, electrode or piezo igniter
• Safety interlock still engaged after turning OFF
• Pilot adjustment closed, gas shut-off closed, pilot orifice or tube blocked
• Defective spill switch (gravity-vented Millivolt systems)

Check in this order

1. Press the piezo and look for a spark at the pilot hood. None: check the wire connection at the piezo end, electrode position, pinched or broken ignition wire, cracked porcelain on the electrode base, then replace the piezo.
2. Turn the knob to PILOT, push in and spark. If it still will not light, realign the knob and retry.
3. With the gas off, hold a flame at the pilot hood and push the pilot knob: if the flame bends away, there is air in the line - purge it through the inlet pressure port. If it does not bend, there is no gas flow: check the pilot adjustment screw is not closed, gas shut-offs are open and inlet supply is correct.
4. Inlet pressure typically 7 in. w.c. natural gas / 11 in. w.c. LP (follow the appliance spec).
5. After turning the knob to OFF, the safety interlock blocks relighting until the thermocouple cools (30 s or less).
6. Check the pilot orifice and tube for blockage; replace the valve if all else is good.
7. Millivolt (gravity vent) systems with a spill switch: check continuity across the spill switch; replace if open or high resistance.

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