Water Source Heat Pump System: Things To Know

Water Source Heat Pump System: Things To Know

Learn more about the operation of the water source heat pump system and its components, and then you can make your decision for your new or existing building.

Utilizing the natural heat energy that is present all around us in the ground, the atmosphere, and even in water through the use of heat pumps is a novel idea. They can heat your house without using gas by utilizing the heat already there, lowering the amount of CO2 your house emits.

The parts of a water source heat pump will be discussed in this article, along with examples of how they carry out the refrigeration cycle.

Below are other types of heat pumps:

What is a Water Source Heat Pump?

The natural heat found in lakes, ponds, rivers, springs, wells, or boreholes can be used by a water source heat pump to heat your home. Before being supplied to your taps, radiators, and underfloor heating, the heat it sources can be heated further with electricity.

It is possible to switch out the gas boiler in your home for a water source heat pump, and it is anticipated that heat pumps will become more and more common over the next few years.

The Components of a Water Source Heat Pump

A water source heat pump has the following components:

Water Source Heat Pump System: Things To Know
  • Compressor
  • 4-Way Reversing valve
  • Refrigerant-Water Heat Exchanger
  • Thermal expansion device
  • Coil
  • Fan

Together, these parts effectively carry out the refrigeration cycle and condition the space.


The WSHP’s compressor is its brain. By forcing the refrigerant through the heat pump, it drives the refrigeration cycle and, depending on the temperature signal from the thermostat, either cools or heats the space. This article’s discussion of the refrigeration cycle will focus on its initial phase. A medium-temperature refrigerant gas is pressurized by the compressor to become a high-pressure, extremely hot gas.

The compressor is either rotary or scroll in design for the majority of water source heat pumps currently in use. To do this, they simply combine two distinct geometries.

Rotary Compressor

Most water source heat pumps with cooling capacities under 2 tons on the market today use rotary compressors. A rotary compressor is one that uses an electric motor to rotate an offset ring inside of a cylinder to continuously draw in and compress refrigerant.

Scroll Compressors

A scroll compressor also referred to as a rotary scroll, functions similarly to a rotary. The rotor and stator’s shapes are where the difference is found. Two scroll patterns take the place of the ring and cylinder. The refrigerant gets caught in the space between the rotor and stator scroll patterns, where it is gradually compressed as the rotor scroll is translated.

How a Ground Source Heat Pump Works | GreenMatch

The final stage of the previous cycle is also the first stage of compression for a scroll compressor. Two different volumes of refrigerant can be absorbed and compressed by the scroll simultaneously. The refrigerant is forced into smaller and smaller spaces during the subsequent three stages until the volumes converge and are fully compressed at the scrolls’ center.

There is no need for a valve to maintain the pressure prior to compression because once the refrigerant reaches the center it is fully compressed and released into the hot gas line of the refrigerant cycle.

4-Way Reversing Valve

The component that distinguishes heat pumps from air conditioners is the 4-Way Reversing valve, which is a system component. Depending on whether the space needs to be heated or cooled, the valve controls the flow of hot gas leaving the compressor. When the hot gas exits the compressor, a valve will either direct the flow to the coil for heating or to the heat exchanger for cooling.

A slider inside the valve body moves back and forth in response to the need for cooling or heating. The slider moves to the left when the system needs cooling so that the compressor discharge flows to the heat exchanger.

The slider shifts to the right and controls the flow of the coil when there is a need for heating. Depending on the situation, the slider movement will either remove heat from the room or add heat.

Refrigerant-Water Heat Exchanger

The refrigerant exits the 4-way mixing valve and travels to the refrigerant-water heat exchanger during a cooling cycle. The fan and coil on the exterior unit of the residential unit mentioned above are built to reject heat to the outside air. In place of the outdoor fan and coil, the heat exchanger in a water source heat pump does their job.

A water loop is provided by the building for this system to function. For the water entering and leaving the unit to be maintained for optimum performance, a cooling tower and a boiler are included in the water loop.

The heat exchanger is a coaxial design, with the building loop water running between the refrigerant tube and an outer tube while the refrigerant travels through a tube on the ID of the heat exchanger. The refrigerant’s compressed hot gas is cooled by transferring heat to lower-temperature water. While the refrigerant exits as a high-pressure, low-temperature liquid, the water leaves the heat exchanger at a higher temperature.

Water Source Heat Pump System: Things To Know

Thermal Expansion Device

The high-pressure, low-temperature refrigerant liquid once more leaves the heat exchanger and moves in the direction of the thermal expansion device during the cooling cycle. This regulates the flow of refrigerant into the coil. The cycle’s low-pressure and high-pressure components are divided by the thermal metering device, which is located at the compressor. When the refrigerant moves into the low-pressure area it “evaporates” and cools very rapidly.

However, the thermal expansion device actively monitors the temperature of the refrigerant leaving the coil and adjusts to get the right amount of cooling through the coil. Simply separating the high-pressure and low-pressure areas could be accomplished with just a specially-sized orifice.


The coil is made to make it easier for heat to move from the air to the refrigerant. Increasing the surface area of the coil’s contact with the air is the aim of the coil design. The coil is a series of tubes that are “coiled” back and forth. Fins that have a high surface area for heat transfer are positioned between the tubes, typically at a density of 14–15 fins per inch.

The size of the coil and the number of refrigerant circuits that pass through the coil are created to give the space the ideal level of cooling or heating. The heat from the air is transferred to the refrigerant as the air moves through the coil during cooling.


In the WSHP, the fan is the second-largest electricity consumer. Depending on the size of the unit, the fan, and coil are designed to work together to provide the space with the appropriate level of conditioning. For maximum efficiency, most modern units use fans with electro-commutated motors (ECM).

The fan on the Engineered Comfort Serenity WSHP line adjusts according to the need for conditioning and has a cooling and heating CFM.

Water Source Heat Pump System: Things To Know

How Does a Water Source Heat Pump Work?

A refrigerant is used by a water source heat pump to transfer heat from the water to your house. You should be familiar with both closed-loop and open-loop systems before continuing. Due to the potential for water contamination, a closed-loop system involves piping water diluted with antifreeze through a series of coils or heat exchange panels submerged in the water source, such as a lake.

The mixture draws energy from the water as it passes through the coils and transfers it directly to the heat pump. Water from the lake is pumped directly into the heat pump in open-loop systems. The water can be pumped back into the lake after the heat has been removed from it.

For heat pumps, water is a very suitable heat source as well. Groundwater consistently ranges in temperature from 7 to 12 degrees Celsius, even on chilly winter days. It is necessary to extract groundwater through a supply well and transport it to the evaporator of a water/water heat pump in order to use it for a heat pump. The water is then directed through a return well after cooling.

Although it should be noted that temperatures will vary quite dramatically depending on the season, surface water (lakes or rivers) can also be used as a heat source.

Heat will always be transferred from the water to a middle plate heat exchanger, regardless of the type of system you have. The energy is transferred to the heat exchanger or evaporator of the heat pump via an intermediary circuit, where it is absorbed by a refrigerant. The refrigerant transforms from a liquid into a gas as it gets hotter.

Since refrigerant is such a potent heat absorber, it can absorb heat even at very low temperatures. Heat pumps are ideal in cold climates because of this.

Conclusion: Water Source Heat Pump System

The Water Source Heat Pump System is a great option for a high-rise residential development for a variety of factors, including low investment cost, efficiency, ease of maintenance, building aesthetics, and comfort.

The option of passive cooling is one significant advantage of water (and ground) source heat pumps in the summer. It is also known as “natural cooling”. The ground water’s cooler temperatures are directly transferred through this process into the home’s heating system.


Are Water Source Heat Pumps Good?

One of the most efficient and reliable HVAC systems for your building is a Pump that heats water from a source (WSHP). A simple-design WSHP uses a cooling tower loop to reject heat during the cooling cycle.

How Do You Size a Water Source Heat Pump?

For decades, most contractors have sized HVAC systems, like heat pumps, by dividing the total square footage of a home by 500 to estimate how many tons of heat a home needs. This general rule of thumb recommends a 4-ton system for a 2,000-square-foot home. One “ton” in heating speak is equal to 12,000 BTUs.

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