Lennox 51W27 Thermal Expansion Valve(Txv) Valve

The Lennox 51W27 Thermal Expansion Valve (TXV) Valve is one of the vital accessories of HVAC systems that controls the refrigerant flow rate in the evaporator coil. It is constructed of brass and has a sensing bulb that contains the refrigerant. This bulb works as a temperature indicator. With the reduction of the evaporator coil temperature the pressure in the sensing bulb also reduces. This pressure reduction makes the valve open more to allow more refrigeration to come into the evaporator coil to heat air.