Lennox 78H40 Expansion Valve

The Lennox 78H40 Expansion Valve is a critical 6-ton thermostatic expansion valve (TXV) engineered for precise refrigerant metering in high-capacity light commercial and residential cooling systems. As a veteran-grade HVAC replacement part, the 78H40 (identical to Lennox 78H4001) regulates refrigerant flow into the evaporator coil by sensing heat load changes, preventing liquid slugging and ensuring the compressor receives superheated vapor. This TXV for air conditioning maintains optimal superheat levels across varying ambient temperatures, which is essential for preserving system efficiency and preventing premature component failure. Designed specifically for Lennox 6-ton units, this valve features a durable construction and calibrated sensing bulb for responsive HVAC cooling performance. Whether you are performing a routine expansion valve replacement or troubleshooting a refrigerant flow restriction, this OEM-spec component provides the HVAC reliability required for demanding 6-ton applications.

• Precise Refrigerant Metering: Automatically adjusts flow to maintain the correct evaporator superheat, protecting the compressor from liquid floodback.
• Direct OEM Compatibility: This 6-ton TXV is a drop-in replacement for part numbers 78H40 and 78H4001, ensuring a perfect fit and simplified installation.
• Enhanced System Efficiency: Optimizes coil performance in 6-ton systems, reducing energy consumption and maintaining consistent discharge air temperatures.
• Rugged Mechanical Design: Built to withstand high-pressure environments typical of commercial split systems and large-tonnage rooftop units.

Is the 78H40 compatible with R-410A systems?
Yes, this Lennox expansion valve is designed for modern high-pressure refrigerants typically found in 6-ton HVAC equipment. Always verify the specific refrigerant and pressure ratings on the unit nameplate before brazing.

What are the symptoms of a failing 6-ton expansion valve?
Technicians should look for low suction pressure, high superheat, or frost forming at the valve outlet. Valve hunting (rapid fluctuating pressures) is also a common indicator that the internal needle or power element is failing.

How do I confirm if 78H40 and 78H4001 are the same part?
In the Lennox parts catalog, the 78H40 and 78H4001 are functionally and physically identical. The 78H4001 is often the bulk or service part number used for the same 6-ton valve assembly.

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.