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Allparts Equipment & Accessories 0820643 SIT 820 Nova mV Natural Gas Millivolt OEM Replacement Gas Valve for Vent Free Fireplaces, Stoves, and Gas Logs

4.8 (1) Write Review
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$189.90

$ 82 .99 $82.99

In Stock

About this item

  • Quality SIT Component – OEM-compatible with Majestic, Monessen, IHP, Lennox, Empire, HHT, Tavis Industries, and Napoleon Empire fireplaces, gas logs, and stoves it offers years of reliable service.
  • Buy With Confidence – Trust in Sit Control OEM superior quality heating replacement components. Each product undergoes rigorous quality checks to ensure peak performance and longevity. So, prioritize your comfort and safety with our reliable OEM Sit Controls solutions.
  • Natural Gas Millivolt Control – This Sit-820 Nova Series gas control valve is specifically designed for Natural Gas Unvented applications for optimal performance and compatibility with all major brands.
  • Adjustable Flame Control – Offers both high and low flame settings, giving users the flexibility to set the desired ambiance. Plus, it features a quick drop-out pilot circuit to enhance safety when a low pilot is sensed.
  • Replaces Multiple Models – Vent Free Only replacement for model numbers J3836 and 103781-01.
  • USA BASED - We take pride in distributing our products right here in the United States. We are committed to delivering superior products that ensure performance, reliability, and durability. Additionally, we offer top-tier USA based technical support to assist you with any questions or issues, ensuring you receive the best possible experience with our products.


Product Description

0820643 gas valve features
0820643 natural gas valve key components
0820637 wire placement diagram

Thermopile Wire Connections

Placement of the red and white wires from the thermopile generator.

Gas valve with a hi and low burner knob that can be adjusted manually

Adjustable Flame Control

Features manual adjustable flame control with a drop-out pilot circuit to enhance safety.

0820643 gas valve thermocouple block position

Thermocouple Block

Thermocouple block ships in position 1 and comes with instructions to change positions if necessary for thermocouple placement.

Thermocouple port on a SIT 820 Nova gas valve

Thermocouple Connection

First position (standard) thermocouple connector placement.

  • This valve has a M8x1 port.

0820643 Specifications:

Minimum Voltage 145mV with a coil resistance of 2.25±0.5
Drop-out Current Greater than 80Ma with coil resistance of 0.018±0.003
Thermo-electric Unit Hold-in current less than 200Ma
Manual Pressure Set Point 3.5" w.c. ±0.3
Range Of Adjustment 3.5” w.c. -1.6” w.c. Set at 30K btu/hr
Thermocouple Connection M8x1
Max Natural Gas Inlet Pressure 1/2 PSIG

Additional Details

The SIT Controls 0820643 gas valve is a remote ready Natural Gas valve with variable flame adjustment and a split-system Millivolt control. It is only intended for use in unvented appliances.

- It must be used in conjunction with an approved ODS pilot system with a thermocouple and thermopile generator

- This is a Natural Gas valve

- Maximum @ 1 in. w.c. pressure drop 100,000 BTU per hour Regulation capacity 5,000 to 195,000 BTU AP per hour


Gary G.
Reviewed in the United States on February 24, 2025
This valve was purchased to replace an over 20 year old valve on a gas log. The valve configuration was totally different than the old valve. For example, the old valve had outlet and supply to burner in the center of valve.The new valve has outlets on the ends of the valve. Also, new valve is about 1/4 inch wider than old valve so mounting hold down needed to be modified.The old gas lines were aluminum that could be shaped to fit new configuration so it could be reworked to fit.You can't use copper tubing because gas lines are different sizes and the fittings are only designed for gas applications.It was totally reworked and is working fine but you need to be a serious do it yourselfer because the manufacturer probably wants you to buy new gas logs instead of repairing the old one.Also you need m8x1 thermocouple and thermistor to make the valve work. Also thermocouple holder needs to be reworked.Also nothing is labelled on valve and no instructions come with valve so you have to know some things to repair.