TXV

Equipment and Systems - HVAC Costs pillar

Also known as: Thermostatic Expansion Valve

Thermostatic Expansion Valve. The metering device that controls refrigerant flow into the evaporator, replacing fixed orifices in modern AC and heat pumps.

A TXV (Thermostatic Expansion Valve) is the modern refrigerant metering device used in efficient AC and heat pump systems. It modulates refrigerant flow to maintain optimal superheat at the evaporator outlet under changing load conditions, which is why TXV-equipped systems deliver their nameplate efficiency across a wider temperature range than fixed-orifice systems. Required on most ENERGY STAR-rated equipment. The bulb on the suction line is the TXV's sensor; if it falls off the suction line, the AC will fail to cool properly.

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