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​The energy efficiency of heat pumps for water heating

Views:0     Author:Site Editor     Publish Time: 2021-11-18      Origin:Site

hot water heat pump takes heat energy from the outdoor air and transfers it to the stored water in a cylinder. It can also use a ground or water (a river or lake) heat source, but these sources are less common for residential use.

Here is the content list:

Advantages and disadvantages

The energy efficiency of heat pumps for water heating

Heat pump configuration


Advantages and disadvantages

Advantages of hot water heat pump include:

1) efficient conversion of energy to heat

2) the energy source is always available

3) it can provide energy-efficient heating for large amounts of water for use for space heating (e.g. underfloor), hot tubs, and swimming pools

4) it can be used to boost other water heating systems

5) government subsidies may be available.

hot water heat pump

Disadvantages of air-to-water hot water heat pumps include:

1) loss of efficiency as temperature decreases below 6–7ºC although some will continue to provide heating in temperatures down to -10–15ºC

2) purchase and installation costs are higher than for standard electric storage cylinder systems

3) space is needed to install the exterior unit

4) penetrations have to be made through the building cladding

5) outdoor units may be noisy

6) less efficient with low water use (1 or 2 person households)


The energy efficiency of heat pumps for water heating

hot water heat pumps are a highly efficient method of water heating and offer the most efficient electricity-based option, as the electricity is used only to move the heat, not to create it. They can have a coefficient of performance (COP) of between 2.0 and 3.0, which means they create two to three times the energy for water heating than they use in electricity to run the pump and fan. Some hot water heat pump include an electrical heating element to supplement the hot water heat pump output in colder conditions.

As noted above, hot water heat pump efficiency, particularly with air-to-water hot water heat pumps, is reduced by low outdoor temperatures.


To enhance efficiency, the hot water heat pump unit could be operated when:

1) outdoor temperatures are warmer (such as during the afternoon), which improves the performance of the system

2) the price of electricity is lower (such as a night-rate tariff)

3) surplus electricity is available from a photovoltaic system that would otherwise be exported to the electricity grid.

When considered throughout the year, the energy efficiency of air-to-water hot water heat pumps is comparable to solar water heating. hot water heat pump is therefore particularly suited to sites with poor solar gain.

hot water heat pumps have a less variable heat source, but with their high set-up costs and ground area required, they are more suitable for multi-residential developments or very cold climates.


Heat pump configuration

There are two different types of hot water heat pump systems:

1) all-in-one integrated systems, which have the heat exchanger and the storage cylinder in a single unit, located outside

2) split systems, which have the heat exchanger set up separately from the storage cylinder. In this case, the cylinder can be either inside or outside.


MICOE has developed a variety of different hot water heat pumps. If you are in the hot water heat pump business, you can consider using our cost-effective products.