The term Domestic hot water requires some definition as it can be misleading.  DHW (Domestic Hot Water) is considered as hot water used solely for domestic properties and dwellings. This is not entirely accurate, DHW is used for domestic purposes such as showers, sinks, bathing, and general ablutions. DHW heating means that hot water is used in both domestic and commercial DHW purposes.

Climate change is high on the international policy schedule with focus directed towards reducing CO2 emissions. The heating sector is seen as a significant area that requires the reduction of CO2 emissions. This is leading to many questions regarding new technologies and purposes for commercial DHW heating. Therefore, within this blog we address the frequently asked question: “Can Commercial Heat Pump technology be used for commercial DHW?'

Commercial DHW and a building’s energy.

Quantities of energy a property requires for commercial heating can be decreased by best practice design principles. Guaranteeing the property is thermal efficient will lead to the building requiring less energy for commercial heating and commercial DHW. Although, DHW heating is not concerned by this idea as demand is likely to remain continuous.

Domestic and commercial premises that include DHW facilities are likely to be supplied by a gas-fired appliance, such as a Continuous Flow Water Heater or Gas Fired Storage Water Heater.

One of the problems faced with commercial DHW production is that it can be liable to naturally occurring bacteria proliferation. Bacteria can develop if the DHW is not produced or stored properly. The easiest method of counteracting bacterial growth is to decrease storage volumes or use appliances that achieve temperatures above 60 degrees Celsius.

Following the above methods will ensure that bacteria will not have time to grow or will be eliminated promptly by heightened temperatures. The latter is ideal for gas-fired appliances as they can achieve elevated temperatures quickly as system operation includes high temperature on call.

Until low carbon to zero carbon gaseous fuels such as hydrogen and rDME become available gas appliances will continue to use fossil fuels as their source of energy. Commercial Heat pump technology can therefore play a key role in immediate domestic and commercial decarbonisation.

Can commercial Heat Pumps be used for commercial DHW?

Commercial heat pump technology can be used for commercial DHW, whether they be commercial air source heat pumps or ground source heat pumps.

Considerations for Heat Pump Purchase

Temperature requirements – commercial Heat Pumps will require a tank to transfer and store heat. This will therefore require temperature management owing to the potential proliferation of bacteria in the water.

Legionella control – ACOP L8 as well as Building Regulations need stored water to be kept at 60 degrees celsius. This temperature ensures the reduction of Legionella proliferation.

Hot water – Legionella bacteria would be killed off at 55° C. There are also other measures we can take into fact with the system design to further reduce any Legionella bacterial growth.

Oversizing – Prevent oversizing on storage and make sure the water held within the system is used at least once or twice per day. For commercial Heat Pumps with a maximum limit of 55° C we could look at including immersions within the cylinder. These immersions could be programmed to operate daily at 60° C or above, thus killing the bacteria. This process would be classed as a pasteurisation cycle.

In conclusion, commercial heat pumps can supply commercial DHW. However, designers must be considerate of the design considerations and performance requirements to ensure optimum system is positioned.

For more information and schematics on domestic hot water heat pump design, download our brochure today!

Or visit the Rinnai commercial heat pump page:

Commercial Heat Pump Technology :: Rinnai UK (rinnai-uk.co.uk)

We recognise that air source heat pump design is not a straightforward task, so we aim to take the pain out of the process with our design support, capital expenditure, operational expenditure and carbon modelling.

For a free consultation with our heat pump experts contact us today on 0300 373 0660 or

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