How do commercial heat pumps work?

As we are all aware government rhetoric and legislation is leading to an increased interest in commercial heat pump technology for domestic hot water production and heating. This growing interest in commercial ground source and air source heat pumps is leading to many questions from gas installers, consultants, large commercial users, and the public. The questions are somewhat endless stemming from air source heat pump efficiency, ground source heat pump installation and much more!

In this blog our Head of Technical, Peter Seddon will be covering the simple question of just how does a commercial heat pump work? What are the key components and how do they all meld together to make a commercial heat pump system.

Commercial heat pumps work in a comparable way to other consumer appliances.

A commercial heat pump uses similar technology and operates in a similar way to an everyday consumer product, a common refrigerator. A “fridge” operates by removing heat from within the cabinet and exhausts this heat into the room. A heat pump follows a similar process however it is installed outside and extracts heat from the outside air and then transfers the heat generated into a body water.

What are the main components of a commercial heat pump?

A Heat Pump has four main components within the closed circuit which is also known as the refrigerant circuit.

These components are:

  1. The Compressor.

A compressor is used to move gaseous refrigerant through the refrigeration circuit, and a heat exchanger, which extracts heat from the source. The heat is then passed on to a heat sink through another heat exchanger.

     2.The Condenser.

The Condenser is a form of heat exchanger and is used to transfer the heat from the hot compressed gas into the water without coming directly in to contact with each other. As a lot of the heat is removed from the gas it will now change state from a gas to a liquid but will still be high pressure.

     3.The Expansion Device

The expansion device allows the pressure of the refrigerant to be lowered which in turn will allow its state to be changed at lower temperatures which is crucial for the whole process.

     4. The Evaporator.

The Evaporator is the component that starts the process all over again and is another form of heat exchanger. By using a fan, it draws air across the Evaporator which allows the refrigerant to change state back into a low-pressure gas ready to go back into the compressor. This then goes back to the compressor to continue to the cycle.

There are of course a lot more components within the heat pump that are integral to its operation and the overall heat pump efficiency such as thermistors to monitor the temperature of the refrigerant and the Control Board to ensure the desired output is achieved.

Commercial Heat Pumps can transfer heat even in minus temperatures, air source and ground source heat pumps could generate heat as low as -20°C ambient temperature. Conversely, they also create heat at extremely high temperatures. This is achieved because of the low boiling point of the refrigerant gases.

Commercial heat pumps generally use less energy to operate than they output in heat energy, making them extremely efficient - However when the temperature lift for commercial water heating or space heating is substantial (Temperature lift = outdoor air temperature and the temperature heat is delivered at within the building).

The heat pump efficiency i.e., COP or SCOP will reduce, therefore many heats pumps work at their optimum with low temperature heat distribution systems (such as underfloor heating) and why performance reduces dramatically when a heat pump is required to supply heat at high temperature for conventional for domestic hot water.

Commercial heat pumps, so that is how they work!

 As described commercial heat pumps are very similar to domestic heat pump models and other domestic appliances. To review the complete range of Rinnai commercial air source heat pumps visit Commercial Heat Pump Technology :: Rinnai UK (

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 (

Useful resources;

Home - Heat Pumps

Check if a heat pump could be suitable for your home - GOV.UK (