H6209 SIT MILLIVOLT VALVE – Natural Gas – Millivolt
H6209 SIT MILLIVOLT VALVE – Natural Gas – Millivolt
✔ In stock — Usually ships in 1–2 business days
In a millivolt system, the valve is operated by low voltage generated by the pilot assembly thermopile and allows gas flow only when the safety circuit is properly established.
Not sure if this is the right part?
Before ordering, check the following:
- Locate your model number (typically behind the lower louver or inside the control compartment)
- Confirm your unit uses a millivolt (standing pilot) system
- Confirm your gas type is natural gas
- Compare your existing valve to the images provided
⚠️ This part is NOT for IPI (electronic ignition) systems
⚠️ This part is NOT for propane (LP) units
If unsure, refer to your manual or contact us for help identifying the correct part.
🔁 Using propane (LP) instead of natural gas?
This part will not work. View the correct LP version here: 88J53
Compatible Models
Astria Gas Fireplaces:
Altair40DMN
Altair40DMNB
Altair45DMN
Altair45DMNB
Gemini33RMN
Gemini33TMN
Gemini33TMN-B
Gemini35DMN
Gemini40DMN
Gemini45DMN
Libra40CLDMN
Libra40CRDMN
Libra40PFDMN
Libra40STDMN
Marin40STMN
Lennox Gas Fireplaces:
DR3025CNM
DR3025FNM
DR3530CNM
DR3530FNM
DR4035CNM
DR4035FNM
DR4540CNM
DR4540FNM
DRH3025CNM
DRH3530CNM
DRH4035CNM
DT3025CNM
DT3025FNM
DT3530CNM
DT3530FNM
DT4035CNM
DT4035FNM
DT4540CNM
DT4540FNM
DTH3025CNM
DTH3530CNM
DTH4035CNM
EBCRNML
EBCRNMR
ED4035CNM
ED4035CNM2
ED4540CNM2
EDCLNM2
EDCRNM2
EDCRNML
EDCRNMR
EDPFNM2
EDSTNM2
EDV3530CNM
EDV3530CNMB
EDV4035CNE
EDV4035CNM
EDV4035CNMB
EDV4540CNM
EDV4540CNMB
EDVCLNM
EDVCRNM
EDVPFNM
EDVSTNM
ELDV35NM
ELDV40NM
LSM40MN
MLDVT30NM
MLDVT35NM
MLDVT40NM
MLDVT45NM
MPB3328CNM
MPB3530CNM
MPB35STNM
MPB4035CNM
MPB4540CNM
MPD35STNM
MPD35STPM
Superior Gas Fireplaces:
B40RMN
BBV36RMN
BBV42RMN
BDM35
CDCLCMN
CDCLCMP
CDCRCMN
CDCRCMP
CDPFCMN
CDPFCMP
CDSTCMN
CDSTCMP
D500CMN
D600CMN
D800CMN
DR400CMN
DR500CMN
DR600CMN
DR800CMN
DT400CMN
DT500CMN
DT600CMN
DT800CMN
DVA33RMN
DVA33TMN
DVC38RMN
DVC38TMN
DVC43TMN
DVCLCMNS
DVCLRRMNS
DVH33RMN
DVH33TMN
DVPFCMNS
DVPFRMNS
DVR38RMN
DVR38TMN
DVR43TMN
DVR5CMNA
DVR5RMNA
DVR6010CMNS
DVR6010RMNS
DVR6CMNS
DVR6RMNS
DVSTCMNS
DVSTRMNS
DVT5CMNA
DVT5RMNA
DVT6010CMNS
DVT6010RMNS
DVT6CMNS
DVT6RMNS
DVT8CMNS
DVT8RMNS
EBPFNM
EBSTNM
EBVCLNM
EBVCRNM
EBVPFNM
EBVSTNM
ED3530CNM
ED4035FNM
ED4540CNM
ED4540FNM
EDPFNM
EDR3530CNM
EDR3530FNM
EDSTNM
EDT3530CNM
EDT3530FNM
ELDV45NM
LSM40MN2
LSM45MN
LSM45MN2
SDDV35NM
SDDV35PM
SDDV40NM
SDDV40PM
SSBV3530CNM
SSBV4035CNM
SSDVPFCNM
SSDVR3328CNM
SSDVR3530CNM
SSDVR4035CNM
SSDVSTCNM
SSDVT3328CNM
SSDVT3530CNM
SSDVT4035CNM
SSDVT6010CMNS
System Type
This is a millivolt standing pilot system. These systems use a continuously burning pilot flame and do not require household electrical power for basic operation.
Millivolt systems are commonly found in many direct vent gas fireplaces and are known for simple, reliable operation.
This system commonly includes:
- Thermocouple — helps keep the pilot gas valve open when the pilot flame is proven.
- Thermopile — generates millivolt power used to operate the main gas valve.
- Igniter electrode — provides manual spark ignition, usually from a push-button piezo igniter.
- Pilot tube — delivers gas from the valve to the pilot assembly.
Because these systems do not rely on external power, they can often operate during a power outage when used with a manual switch or compatible battery-free control setup.
These systems offer improved efficiency, remote-control compatibility, and added safety features, but they also include more electronic components than a millivolt system.
Common Problems This Valve Fixes
If your fireplace uses a millivolt (standing pilot) system, the gas valve is the control center. When it begins to fail, it can cause a range of frustrating and sometimes confusing issues.
Replacing the valve often resolves the following problems:
- Pilot stays lit but burner will not turn on
The valve is not opening when it receives voltage from the thermopile. - Fireplace turns on intermittently or unpredictably
Internal valve components can wear out, causing inconsistent operation. - No response from wall switch or remote
Even with a good thermopile, a faulty valve may not react to the signal. - Burner shuts off unexpectedly
The valve may be failing internally and dropping out under load. - Weak or unstable burner flame
Improper gas regulation inside the valve can affect flame performance. - Gas flow issues, low flame, or no flame
A failing valve can restrict or inconsistently supply gas to the burner. - Clicking or switching sounds but no burner ignition
The system is calling for heat, but the valve is not opening. - Valve knob feels loose, stuck, or does not function properly
Mechanical wear or internal damage to the valve body may prevent proper operation.
Important Note
Many of these symptoms can also be caused by a weak thermopile, thermocouple failure, dirty pilot assembly, switch wiring issues, or improper gas pressure. Proper diagnosis is strongly recommended before replacing the valve.
Warranty Information
This product includes a 12-month warranty from the date of purchase. This warranty covers defects in materials or workmanship under normal operating conditions.
Fireplace components must be properly installed and matched to the correct system (millivolt vs IPI, natural gas vs propane).
This warranty does NOT cover:
• Improper installation or incorrect application
• Use with the wrong gas type (NG vs LP)
• Misdiagnosis of the issue
• Damage caused by other failing components
• Normal wear and tear
• Labor, service, or diagnostic time
Because many fireplace issues can be caused by multiple components, we strongly recommend confirming the diagnosis before replacing parts.
We are happy to assist with this. Proof of purchase is required for all warranty claims. Please contact us prior to removal or replacement of the part so we can help verify the issue and guide the warranty process.
How do I know if my valve is bad?
Common signs of a failing gas valve include the pilot staying lit but the burner not turning on, no response from a wall switch or remote, intermittent operation, or the burner shutting off unexpectedly.
In some cases, the valve may fail to open and allow gas to flow, even though the system is calling for heat. You may also notice inconsistent flame behavior or complete loss of burner function.
Before replacing the valve, it is important to verify that other components such as the thermopile, thermocouple, ignition module, or wiring are functioning properly, as these can cause similar symptoms.
How difficult is this part to replace?
Replacing a gas valve is considered a moderate to advanced repair because it involves working with gas lines and critical safety components.
The process typically requires shutting off the gas supply, disconnecting and reconnecting fittings, and ensuring all connections are properly sealed and leak-free. In many cases, adjustments or system checks are also needed after installation.
For safety and proper operation, installation is recommended to be performed by a qualified technician.
Is this a safe DIY repair?
Gas valve replacement involves working with gas lines and safety-critical components, so it is generally not recommended as a DIY repair for most homeowners.
Improper installation can result in gas leaks, unsafe operation, or damage to the fireplace system. Correct procedures, proper tools, and leak testing are essential to ensure safe operation.
For safety and reliability, installation is recommended to be performed by a qualified technician.
Do I need any special tools to install this?
Gas valve replacement typically requires standard hand tools such as wrenches and screwdrivers, along with gas-rated thread sealant or tape for proper sealing of fittings.
A manometer may also be needed to verify proper gas pressure after installation, and leak detection solution is required to ensure all connections are safe and secure.
Because proper setup and testing are critical for safe operation, installation is recommended to be performed by a qualified technician.