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Reverse Cycle Chiller

Heat pump uses hot water as the source for auxiliary heating demands

The Reverse Cycle Chiller uses a high efficiency heat pump to heat or chill a glycol/water solution for residential heating and cooling. Photo credit: Aqua Products Company

Air-source heat pumps provide efficient heating when outdoor conditions are moderately cool, but lose capacity in very cold weather when auxiliary heat is required, typically supplied by less efficient electric resistance strips. The hydronic "Reverse Cycle Chiller™ (RCC)" heat pump uses hot water as the source for auxiliary heating demands. The manufacturer claims that the RCC will supply residential heating with greater comfort and improved cost-efficiency, even when exterior temperatures are below zero.

Heat pumps work by circulating a working fluid, or refrigerant, which vaporizes at a low temperature (in the evaporator), producing additional energy in the process. A compressor further concentrates the warmed vapor, raising it to a temperature where it can be circulated through an air handler and used for heating. When the cycle reverses, heat is pumped from indoors to out, as with standard air conditioners (in Canada heat pumps are known as "reverse cycle air conditioners") Traditionally, heat pumps have been sized to cooling loads and used where outdoor temperatures rarely fall below freezing. As outdoor temperatures drop, there is less heat available for efficient extraction by the evaporator, and supplemental heat may need to be provided by electric resistance strips. To protect the evaporator from freeze damage, it must occasionally run in a defrost cycle where the flow of refrigerant is reversed, so that heat from the interior of the house will melt accumulated ice deposits in the outdoor coil. This results in uncomfortably cold air being circulated throughout the home during the cycle, a common source of frustration and complaint among heat pump owners.

The Reverse Cycle Chiller, produced by Aqua Products Company, Inc. uses a highly efficient heat exchanger to transfer energy to a water line, achieving temperatures up to 120 degrees in the heating mode, and down to 50 degrees in cooling mode. The water line can then supply a central air handler, a radiant floor heating system or multiple zoned air handlers. This configuration allows the system to be sized for heating loads rather than typically smaller cooling loads. On its return trip towards the evaporator, the water replenishes a super-insulated tank that serves as a "thermal flywheel," replacing resistance strips as the auxiliary heat source, and supplying heat for the defrost cycle. The system is said to supply a more consistent, comfortable level of heating, that operates efficiently, even at temperatures below 0 degrees Fahrenheit.

The technology applied in the Reverse Cycle Chiller is not new. Similar larger scale systems have been in operation for decades in commercial, institutional, and industrial applications, but this hydronic heat pump configuration has not typically been used for single-family residential units.


Energy Efficiency

Reverse cycle chillers can supply higher temperature heating energy than air-source heat pumps, resulting in less use of back-up resistance heating.

Quality and Durability

Reverse cycle chillers can supply higher temperature heating energy than air-source heat pumps, resulting in higher comfort levels for homeowners.


Easy

The equipment is manufactured in Prosperity, SC, and shipped throughout the United States.

As with any new product, long term durability of the equipment has not been established, and independent testing and comparisons to costs and performance of conventional heat pump systems are not yet available.


Aqua Products Company states that equipment and installation costs for a Reverse Cycle Chiller system will be about 25% more than conventional heat pump systems.


Not Applicable


The heat pump equipment used in Reverse Cycle Chiller systems are standard components supplied my major manufacturers. Installation must conform to local building codes.


Not Applicable


The Reverse Cycle Chiller should be installed by a qualified HVAC contractor familiar with both hydronic systems and heat pumps.


Not Applicable


Especially for all electric homes, heat pumps are often the best choice for energy-efficient heating and cooling. The Reverse Cycle Chiller may allow heat pump technology to be used effectively in a wider range of climactic conditions, and provide a higher level of comfort to occupants. If systems can be sized to heating loads, and function efficiently at colder temperatures, the need for costly electric resistance heating strips could be eliminated.

The Reverse Cycle Chiller is fully compatible with radiant floor heating equipment (in heating mode only), and provides a more efficient method of heating the circulating fluid in these systems with electricity. Retrofits using Reverse Cycle Chillers in conjunction with existing radiant floor distribution or air-handling systems may also be possible.

Aqua Products Company also offers an optional equipment package that can provide potable water-heating using the waste heat from the heat or cooling cycles.

Aqua Products Company states that equipment and installation costs for a Reverse Cycle Chiller system will be about 25% more than conventional heat pump systems.

Disclaimer: The information on the system, product or material presented herein is provided for informational purposes only. The technical descriptions, details, requirements, and limitations expressed do not constitute an endorsement, approval, or acceptance of the subject matter by the NAHB Research Center. There are no warranties, either expressed or implied, regarding the accuracy or completeness of this information. Full reproduction, without modification, is permissible.