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What Are the Different Types of Valves Used in HVAC?

Valves in HVAC systems rely on some form of mechanical barriers such as a diaphragm, a plat, or a ball that controls the movement of air or the material passing by. Each type of valve is designed to meet the specific needs of the system.

For instance, some valves can only stop or throttle the flow, and others that handle high-pressure fluids. Therefore, understanding how these differences affect the operation or application of the valve is crucial for the successful operation of an HVAC system. This article discusses the different types of valves used in HVAC systems.

  • Ball Valves
 charging a residential heat pump system with refrigerant
Ball valves are used at the inlet and outlet of indoor units like air handling units, fan coil units, and cooling towers. They are classified as quarter-turn valves used for bi-directional isolation applications. Ball valves result in low friction loss because there is no obstruction in the flow path when it is fully open. It has a conventional body design that controls the flow by the hole position through the ball and can be installed in any direction.

  • Float Valves

Floating valves are used to maintain the quantity of water required in cooling towers. A floating ball is attached to the valve’s lever that opens and closes with a variation in water level. Float valves can serve as a metering device as either a high-side or low-side. The low-side float valve maintains a constant liquid level in the evaporator. The high-side float valve allows the flow of liquid into the low side after the refrigerant is condensed to move the float ball.

  • Check Valves/NRV

Check valves or non-returning valves (NRV) are used at a pump’s discharge outlet to prevent water in pipes from flowing back once it has passed through. These valves are required in lines that feed the secondary CHW system where pressure can rise beyond that of the primary system. Swing check valves can be installed in a horizontal or vertical direction and are easy to maintain compared to flanged models.

  • Gate Valves

The gate valve controls the flow of media by lifting and lowering the gate. Its straight-through unobstructed passageway allows minimal loss of pressure over the valve. Gate valves are available in different options including different temperatures and pressure ratings, materials, sizes, and bonnet designs. They are designed for applications where valve operation is infrequent and is slower in actuation compared to quarter-turn valves.

  • Butterfly Valves

This rotary motion valve stops, regulates, and initiates the flow of air, water, gas, or steam through pipes. Butterfly valves use a disk as a flow control element that rotates in a vertical or horizontal axis. The valve opens fully when the disk is parallel to the piping run and closes when it approaches the perpendicular position. Intermediate positions in butterfly valves can be attained for throttling purposes.

  • Modulating Control Valves

A modulating control valve uses a combination of a valve and a modulating actuator. The actuator uses a feedback system to provide feedback to the operator about the valve’s position. Modulating the valve position helps to regulate the flow rate that controls secondary parameters such as concentration or temperature level. A modulating valve is automated to fully open or fully close and is used for applications that need variation in flow rate.

  • Pressure-Regulating Valves

This type of valves can either control an upstream or downstream pressure but not both. They prevent pressure from rising above or falling below a predetermined level. Pressure-regulating valves control pressure without regard to other processes that go on in the system. They can be used to regulate water pressure in chilled water pipes when commissioning.

  • Balancing Valves

Balancing valves maintains the preset flow conditions to allow control valves to function properly. They help deliver accurate flows to heat-transfer coils to produce the required energy output to space. In other words, balancing valves keep the HVAC system within working parameters by ensuring the right flow rate. They are marked with a scale to control the flow by opening or closing the valve.

Different types of valves operate differently as they can open and close fully or obstruct the passageway partially based on demand and supply. They are designed to regulate the flow of liquids and gases in HVAC systems when paired with actuators. The use of these valves in HVAC applications is very crucial as they allow the successful operation of an HVAC system. If you are planning to install a HVAC system, you should be in touch with an expert for advice on the best valve to go with.

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