Browse Stockpile Express and find thermal expansion valves for your HVAC system. A thermal or thermostatic expansion valve controls the amount of refrigerant released into your air conditioner’s evaporator. Whether you’re performing regular HVAC maintenance or installing a new air conditioner, consider a thermal expansion valve to potentially increase your system’s efficiency, optimize the temperature of your home, and reduce your energy bill. Discover high-quality thermal expansion valves and valve kits in durable, corrosion-resistant copper from Source 1, Nortek, First Co., and other top brands at Stockpile Express.