Before we delve into this topic it would be useful to quantify the meaning of domestic hot water.
Domestic hot water, or DHW, is frequently considered as hot water used solely for domestic properties and/or dwellings. This is not the case, and its term refers to water used for domestic purposes such as showers, sinks, bathing, and general ablutions. So, DHW heating means the hot water used in both domestic and commercial premises.
As climate change is high on the international policy agenda with laser focus on reducing CO2 emissions, the heating sector is seen as a critical area to help reduce CO2. This is leading to many questions surrounding new technologies and applications for DHW heating. Therefore, within this blog we address the frequently asked question “can commercial heat pumps be used for domestic hot water?”.
Domestic hot water and building energy
The energy a building requires for heating can be reduced by best practice design principles; for example, ensuring that the building is as thermally efficient as possible will result in the structure requiring less energy for heating services. This, however, isn’t the case with DHW heating as the demand is likely to remain constant.
Currently in both domestic and commercial premises the DHW services are most likely supplied via a gas fired appliance. Whether that be a combi boiler, continuous flow water heater, gas fired storage water heater, or system boiler with cylinder.
One of the biggest problems faced with DHW production is that it can be susceptible to bacteria growth that is naturally occurring within the water supplies. These bacteria can grow if the DHW is not produced or stored correctly.
The easiest methods to combat or reduce this growth is to reduce storage or use appliances that achieve temperatures within the system above 60˚C, including areas that require stored hot water.
In these instances bacteria will either not have the time to grow or removed rapidly by the elevated temperatures. This is one of the plus factors for gas appliances as they can achieve elevated temperatures quickly or use technology to allow them to operate on demand with temperature accuracy.
At this moment in time, gas appliances use fossil fuels as their energy source so until environmentally friendly gases such as hydrogen and rDME become more readily available, heat pumps can play a key role in the decarbonisation of this sector.
So, can heat pumps be used for DHW production?
In short, the answer is yes, heat pumps can be used for DHW production. Whether they be air source heat pumps, commercial heat pumps, or ground source heat pumps.
This is because they can produce heat which can be transferred into the water in a similar fashion as a system boiler would with an indirect cylinder.
Considerations
- Temperature: Heat pumps will require a cylinder to transfer and store heat. Due to the required storage, we would need to consider temperature management because of the bacteria within the water.
- Legionella: ACOP L8 as well as building regulations require stored water to be kept at 60˚C, which is a temperature that can reduce Legionella proliferation.
- Heat pump performance: The most common heat pumps currently on the market can produce hot water up to 60-63˚C. There are elevated temperature heat pumps available that can generate water temperatures at above 70˚C, but these are not as common just yet.
- Hot water: The Legionella bacteria would be killed off at 55˚C - it just takes longer so we could say that heat pumps producing 55˚C water are perfectly safe doing so. There are also other measures we can take into consideration with the system design to further reduce any sort of risk for Legionella bacterial growth.
- Oversizing: Such measures are to avoid oversizing on the storage and to make sure the volume of water held within the system is used at least once or twice per day. For heat pumps with a maximum limit of 55˚C, we could look at including immersions within the cylinder. These immersions could be programmed to come on daily during quiet periods and heat the water up to 60˚C or above, thus killing off the bacteria. This process would be classed as a pasteurisation cycle.
These measures mentioned are not unfamiliar to the HVAC sector, they are requirements when designing any DHW system whether that be gas fired or electric, so the transition from one to the other could only require a minor adjustment.
So, in conclusion, heat pumps are more than capable of supplying domestic hot water. System designers must be considerate of the design considerations and performance requirements mentioned above to ensure that the optimum system is deployed.
For more information and schematics on domestic hot water heat pump design, download our brochure today! (please check the side bar) or visit our commercial heat pump page.
We recognise that air source heat pump design is not a straightforward task, especially when designing commercial heat pump systems, 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 Help me choose a product :: Rinnai UK (rinnai-uk.co.uk)
Useful resources:
Commercial Heat Pump Design Criteria - Courses | The CPD Certification Service (cpduk.co.uk)
The primary advantage of using Heat pumps for hot water production is that commercial air source heat pumps use ambient air to heat your domestic hot water, making them highly efficient and eco-friendly. By harnessing the natural warmth or thermal energy in the air, heat pumps can reduce energy consumption and carbon emissions considerably then compared to traditional hot water generation methods.
Not only can heat pumps help reduce carbon emissions, but they also offer several other advantages when using heat pumps for hot water. They can provide consistent hot water supply, even in extreme weather conditions. Additionally, heat pumps are highly durable and require minimal maintenance, making them a cost-effective long-term investment.
Read on to find out the numerous benefits of using heat pumps for hot water production.
Learn more about the Rinnai R290 heat pump range.
Energy Efficiency of Heat Pumps for Water Heating
Energy efficiency is one of the standout features of commercial air-source heat pumps, particularly when compared to traditional water heating methods. Heat pumps can achieve a coefficient of performance (COP) of 3 to 5, meaning that for every unit of electricity consumed, they can produce three to five units of heat energy. This efficiency translates into substantial carbon savings and system efficiency.
However it is important to understand the full SPF (Seasonal Performance Factor) of the heat pump system to ensure that any auxiliary heating and system heat losses are factored into the overall system performance.
For free training and CPDs on heat pump design and the importance of SPF visit https://www.rinnai-uk.co.uk/training/cibse-cpd-training-enrolment and sign up today.
In contrast, conventional electric resistance heaters typically have a COP of 1, making heat pumps a much more attractive option to reduce energy consumption. In addition to their impressive COP ratings, heat pumps also maintain efficiency over time.
Technological advancements have led to the development of variable-speed compressors and smart controls that optimise performance based on water heating demands and outdoor conditions. This means that heat pumps can adjust their operation to minimise energy use during periods of low demand, further enhancing their energy-saving capabilities.
Environmental Benefits of Using Heat Pumps for Water Heating
The environmental advantages of heat pumps are significant, particularly in the context of climate change and sustainability. By utilising renewable energy from the ambient air, heat pumps dramatically reduce greenhouse gas emissions associated with water heating. Traditional methods, such as electric resistance heaters or gas-fired boilers, often rely on fossil fuels, leading to higher carbon footprints. In contrast, heat pumps offer a cleaner alternative by harnessing existing heat, thus contributing to lower overall emissions.
Read one of our case studies on a heat pump solution here.
Furthermore, heat pumps can be integrated with renewable energy sources such as solar power. When paired with solar panels, heat pumps can operate with minimal or even zero carbon emissions, depending on the energy source. This synergy not only enhances energy efficiency but also aligns with the growing trend toward sustainable living. As more households adopt heat pumps and renewable energy solutions, the cumulative effect can lead to substantial reductions in carbon emissions, ultimately contributing to global efforts to combat climate change.
Visit https://www.cibse.org/directories/cpd-directory-details/cpd-directory-listing/rinnai-uk-ltd to learn more about Rinnai CPDs on this topic.
Long-term Durability and Reliability of Heat Pumps for Water Heating
Heat pumps are known for their durability and reliability, making them an excellent long-term solution for water heating. With proper installation and maintenance, these systems can last significantly longer than traditional water heaters. While electric resistance heaters may require replacement every 10-15 years, heat pumps can easily provide service for 15-20 years or more.
Another factor contributing to the reliability of heat pumps is their relatively low maintenance requirements. Unlike gas heaters, which may require annual inspections and maintenance to ensure safe operation, heat pumps typically need less frequent servicing. Regular checks on the refrigerant levels, cleaning of filters, and ensuring that the outdoor unit is free from debris are usually sufficient to keep the system running efficiently. This ease of maintenance not only saves time and effort but also minimises the likelihood of unexpected breakdowns.
Conclusion: Is a Heat Pump the Right Choice for Your Water Heating Needs?
If you are environmentally conscious or and ESG requirements for you building or estate of buildings and wish to minimise your carbon footprint, heat pumps are an excellent solution. Their ability to use renewable energy from the air, along with their low emissions, aligns with the goals of sustainable living. In addition, the durability and reliability of heat pumps mean that you can enjoy consistent hot water without the worry of frequent replacements or repairs.
Ultimately, the choice to install a heat pump should be based on your specific circumstances, including your hot water needs, local energy costs, and climate conditions. Consulting with a professional can provide valuable insights tailored to your situation. It is also important to ensure that the SPF of the system is thoroughly understood so that the seasonal performance factors of the system and therefore its true operation are completely transparent.
In summary there are many advantages of heat pumps for use in the generation of hot water provision, with the correct selection, design and ancillaries commercial heat pump technology can have a profound impact on your project carbon emissions and system performance.
For support with system design, operational expenditure, capital expenditure and carbon modelling, contact us for support.
When it comes to heat pumps, there are several types to consider, each designed to suit different environmental conditions and user needs. The primary categories include air-source, ground-source, and water-source heat pumps. Each type operates on the same fundamental principle but differs in the source from which they extract or dissipate heat.
Choosing the right type of heat pump involves considering factors such as climate, installation costs, and energy efficiency. In colder climates, air-source heat pumps may require supplemental heating to operate efficiently during colder temperatures, while ground-source systems tend to offer greater efficiency due to stable underground temperatures. Understanding the specific characteristics of each type can significantly influence your choice and ensure optimal performance in your home.
Air-source heat pumps
Air-source heat pumps (ASHPs) are one of the most popular options. These systems are designed to extract heat from the outside air, even in cooler temperatures, making them suitable for a wide range of climates. ASHPs consist of an outdoor unit that absorbs heat and an indoor unit that distributes it throughout the building. Their relatively straightforward installation process and lower upfront costs compared to ground-source systems contribute to their widespread adoption.
They can provide both heating in the winter and cooling in the summer, making them a year-round solution for climate control. However, their efficiency may decrease in extremely low temperatures. Air source heat pumps come in both domestic and commercial variants and recent advancements in refrigerants like R290 (propane) ensure that these heat pumps can reach much higher temperatures of domestic hot water applications subsequently improving performance and lower costings.
Learn more about our R290 air source heat pump.
Ground-source heat pumps
Ground-source heat pumps (GSHPs), often referred to as geothermal heat pumps, harness the thermal energy stored beneath the Earth's surface. These systems utilise the relatively constant temperatures found underground to provide heating and cooling, making them highly efficient options for year-round climate control. The installation process involves burying a series of loops underground, which circulate a refrigerant to absorb heat in the winter and release it in the summer.
Due to the stable underground temperatures, GSHPs can achieve higher coefficients of performance compared to air-source systems, particularly in colder climates. This translates into reduced energy bills and a smaller carbon footprint. However, the installation of GSHPs can be more complex and costly than other types of heat pumps due to the need for extensive excavation and loop installation. Additionally, the availability of suitable land for installation can influence the feasibility of GSHPs.
Water-source heat pumps
Water-source heat pumps (WSHPs) are another efficient option for heating and cooling homes, utilising a body of water as the heat exchange medium. These systems can extract heat from lakes, rivers, or wells, providing a stable energy source for climate control. WSHPs operate similarly to air-source and ground-source heat pumps, but they use water as the medium for heat transfer, making them particularly effective in areas with access to suitable water bodies.
Because water has a higher heat capacity than air, WSHPs can transfer heat more effectively, resulting in improved performance in both heating and cooling modes. They also tend to operate more efficiently than air-source systems in colder temperatures, making them a viable option in regions with harsh winters. However, installation costs can vary based on the complexity of the system and the distance to the water source.
Hybrid heat pumps
Hybrid heat pumps combine the strengths of different heating technologies to deliver optimal efficiency and comfort. These systems typically integrate an air-source heat pump with a conventional heating source, such as a gas or oil furnace. The hybrid approach allows the system to switch between the two sources based on the current outdoor temperature and energy prices, maximising efficiency and minimising energy costs.
During milder temperatures, the air-source heat pump can provide sufficient heating, and when temperatures drop significantly, the system can automatically switch to the backup furnace for additional heat. Moreover, hybrid systems can enhance energy savings by optimising the use of renewable energy sources. Hybrid heat pumps are particularly appealing for regions with fluctuating temperatures, where a single heating source may not be sufficient to meet varying heating demands.
Learn more about our hybrid hot water solutions
Conclusion: Choosing the right heat pump for your needs
In conclusion, selecting the right heat pump involves careful consideration of various factors, including climate, energy efficiency, size, and system type. By understanding the different options available, such as air-source, ground-source, water-source, and hybrid heat pumps, you can make informed decisions that align with your specific needs and preferences. Each type of heat pump comes with its unique advantages and limitations, so it is essential to evaluate them based on your local conditions and heating requirements.
Ultimately, investing in a heat pump can lead to significant long-term benefits, including, improved comfort, and a smaller environmental footprint. As the demand for energy-efficient and sustainable solutions continues to grow, heat pumps have emerged as a leading choice for enhancing the indoor climate while contributing to a greener future.
For support with system design, operational expenditure, capital expenditure and carbon modelling, contact us for support.
For more information and schematics on domestic hot water heat pump design, download our brochure today!
(Below)