In a water source heat pump (WSHP) application, a variable or constant speed pump accomplishes water distribution. The primary function of valves in a WSHP application is to allow a predetermined volume of water to enter each unit through either a water-to-refrigerant coil, water-to-air coil, or a water-to-water coil. The valves used are typically on/off control for full design flow when the WSHP starts. In most applications they are not required to control the amount of flow as in a traditional HVAC hydronic system.
The benefits of using a pressure independent valve (PIV) for a water source heat pump:
- Dynamically balances the system by responding to changes in differential pressure
- Maintains design flow at part load and during morning start-up when all loops become critical
- Each terminal receives the required flow, no overflow or underflow
- Dynamic balancing allows a mechanic to easily commission a building and eliminates the need for rebalancing when alterations have been made to the hydronic system
- Improves overall comfort and saves on pumping energy
To select the right pressure independent valve determine the appropriate flow required for your heat pump and select the valve that satisfies this flow. Belimo’s pressure independent valve ranges from ½” to 6” with up to 713 GPM. This combination of pressure independent valve and variable-frequency drive (VFD) enables savings of pumping energy up to 90% of the time when the building load is less than full. More information on pressure independent control valves can be found online.