Lennox 34W45 Reversing Valve. Lennox goal is to provide contractors with high-quality HVAC solutions and replacement parts. This system includes changes and inventory updates to ensure peak performance. Lennox has a large line up parts and products for high-efficiency packaged rooftop units, split systems, HVAC controls, furnaces and indoor air quality products. This Lennox 34W45 Reversing Valve features 3 inlets, a motor and a single output that's designed to increase the overall flow in the coils.