HVAC Valves are such components without which we cannot control flow in pipes. They are needed for every media whether it is water, gas, air or any other liquid. Valves would have been needed for solids if they could have ability to flow. Like other areas, valve find its extensive use in HVAC (heating, ventilation and air-conditioning).
Water Chiller, the heart of HVAC system, has valve on inlet and outlet lines of chilled water and cooling water. These valves are usually gate and globe valves which are used for isolation and throttling purposes. Water chiller operates on vapor compression cycle or vapor absorption cycles which also require valves internally as a requirement of thermodynamics. For example Refrigerant expansion valve is needed inside a water chiller cycle. Chilled and cooling water headers also need valves for isolation and heating/cooling changeover.
Basic Types – by function
Check valve or non-return valve, allows the fluid to pass in one direction only.
Flow control valve, to maintain and control a variable flow rate through the valve
Poppet valve, commonly used in piston engines to regulate the fuel mixture intake and exhaust
Pressure Reducing Valve, to regulate the pressure of the fluid.
Expansion valve, used in refrigeration and air conditioning systems.
Safety valve or relief valve: operates automatically at a set pressure to correct a potentially dangerous situation, typically over-pressure