The Leading News & Information Service For The Facilities, Workplace & Built Environment Community

Can Commercial Heat Pumps Be Used For Commercial DHW?


Pete Seddon & Sean Ehlen of the Rinnai Tech Team look at some answers to whether commercial heat pumps can be used for commercial DHW generation.

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! 

Rinnai’s H3 range of decarbonising products includes hydrogen / BioLPG ready technology, hybrid systems, and a wide range of LOW GWP heat pumps and solar thermal. Also, within Rinnai’s H3 range is Infinity hydrogen blend ready and BioLPG ready continuous flow water heaters which are stacked with a multitude of features that ensure long life, robust & durable use, customer satisfaction and product efficiency.

Rinnai’s range of decarbonising products - H1/H2/H3 - consists of heat pumps, solar, hydrogen in any configuration, and hybrid formats for either residential or commercial applications. Rinnai’s H3 range of products offers contractors, consultants and end users a range of efficient, robust and affordable decarbonising appliances which create practical, economic and technically feasible solutions. The range covers all forms of fuels and appliances currently available - electric, gas, hydrogen, BioLPG, rDME solar thermal, low GWP heat pumps and electric water heaters.

Rinnai H1 continuous water heaters and boilers offer practical and economic decarbonization delivered through technological innovation in hydrogen and renewable liquid gas-ready technology.

Rinnai’s H1 option is centred on hydrogen, as it is anticipated that clean hydrogen fuels will become internationally energy market-relevant in the future; Rinnai water heaters are hydrogen 20% blends ready and include the world’s first 100% hydrogen-ready hot water heating technology.

Rinnai H2 – Decarbonization simplified with renewable gas-ready units, Solar Thermal and Heat Pump Hybrids.  Rinnai H2 is designed to introduce a practical and low-cost option which may suit specific sites and enable multiple decarbonisation pathways with the addition of high performance.

Rinnai H3 – Low-GWP heat pump technology made easy - Rinnai heat pumps are available for domestic and commercial usage with an extensive range of 4 - 115kW appliances.

Rinnai’s H3 heat pumps utilise R32 refrigerant and have favourable COP and SCOP.

Rinnai is a world-leading manufacturer of hot water heaters and produces over two million units a year, operating on each of the five continents. The brand has gained an established reputation for producing products that offer high performance, cost efficiency and extended working lives.

Rinnai’s commercial and domestic continuous-flow water heaters offer a limitless supply of instantaneous temperature-controlled hot water and all units are designed to align with present and future energy sources. Rinnai condensing water heaters accept either existing fuel or hydrogen gas blends. Rinnai units are also suited for off-grid customers who require LPG and BioLPG or rDME.

Rinnai products are i2HY20 certified, A-rated water efficiency, accessed through multiple fuel options and are available for purchase 24/7, 365 days a year. Any unit can be delivered to any UK site within 24 hours. Rinnai offer carbon and cost comparison services that will calculate financial and carbon savings made when investing in a Rinnai system. Rinnai also provide a system design service that will suggest an appropriate system for the property in question. Rinnai offer comprehensive training courses and technical support in all aspects of the water heating industry including detailed CPD’s. More information can be found on Rinnai’s website and its “Help Me Choose” webpage.