Lennox 85K35 Valve

The Lennox 85K35 Gas Valve is a rugged, 24V step-open gas control engineered for precision fuel management in commercial and residential Lennox HVAC systems. Designed as a direct replacement for the Honeywell VR8305P4337 and Allied 85K3501, this valve features a 3/4" x 3/4" straight-through body pattern, making it a drop-in solution for high-capacity direct ignition systems. With a factory-calibrated 0.9" to 3.5" WC step-opening regulator, it ensures smooth ignition and stable manifold pressure, effectively dampening "booming" starts in rooftop units and furnaces. This dual-automatic valve configuration meets stringent safety codes by incorporating two solenoid-operated operators that provide 100% shut-off upon power or gas loss. Built for the field, all wiring terminals and pressure taps are top-mounted for easy manometer access during combustion analysis. It is compatible with natural gas applications and serves as a reliable upgrade for older 60J91 and 20515702 series controls across Lennox, Armstrong, and Ducane equipment lines.

• Universal Compatibility: Directly replaces Honeywell VR8305P4337, Lennox 85K3501, and 60J91 models.
• Step-Open Performance: Provides a controlled initial 0.9" WC gas flow before reaching 3.5" WC to prevent hard ignitions.
• High Capacity Design: Features a 3/4" NPT inlet and outlet, supporting high-BTU gas-fired appliances.
• Service-Friendly Layout: Top-accessible 1/4" quick-connect terminals and 1/8" NPT pressure taps for rapid diagnostics.
• Dual Safety Shut-off: Redundant solenoid operators ensure absolute gas closure during a call-for-heat termination.

Common Questions

Can the Lennox 85K35 be converted to Propane (LP)?
While many VR8305 series valves support conversion, the 85K35 step-open model typically utilizes a non-adjustable step regulator. Always verify the specific orifice and spring kit requirements for your Lennox chassis before attempting a field conversion.

What is the purpose of the "Step Open" feature on this valve?
The step-open mechanism allows a lower initial gas pressure (0.9" WC) to reach the burners first, ensuring a quiet and reliable light-off before shifting to the full 3.5" WC operating pressure.

What electrical rating is required for the control transformer?
This valve operates on 24 VAC (60 Hz) with a 0.7A current draw. It is recommended to use at least a 40VA Class 2 transformer to ensure the 85K3501 and the rest of the ignition circuit have adequate power.

Disclaimer: While we strive for 100% accuracy, product data and specifications are subject to change. Please contact our team to confirm compatibility or technical details before purchasing.