Heat pumps are becoming increasingly popular, and yet we often find there are a lot of questions when it comes to understanding how they work, and the things we need to think about if we are considering heat pumps for our places of work (and homes).
Firstly, lets tackle why they can help us reduce our carbon emissions and our energy bills;
In a nutshell, heat pumps run on electricity and are 3-4 times more efficient than conventional boiler heating systems. Meaning much more output for a faction of the input. And when paired with a renewable source of electricity like a solar PVs you can significantly reduce your energy costs.
Let’s explore how they work in a little more depth;
Their success is based on the key relationship between pressure and temperature: When the pressure of a gas increases, the temperature also increases. When the pressure decreases, the temperature decreases.
Heat pumps use the heat in the air or ground and transfer it to a heat exchanger which contains a liquid refrigerant (which contain the potential to turn back into a gas). The refrigerant absorbs the heat and turns into a low-pressure, low-temperature gas. This gas is then transferred to a compressor which uses electricity to further increase the pressure of the gas and in turn the temperature of the gas.
This hot gas then reaches the heat exchanger, where the heat is transferred to the space heating system, be this air or water within the water circuit that is supplying the heat to the output systems, such as radiators and underfloor heating within the premises. (Note when retrofitting to existing heating systems, the temperature delivered from a heat-pump is generally lower than that of a traditional boiler, requiring careful design considerations in ensuring effectively delivery of the heat, especially to domestic hot water systems).
When the refrigerant gas loses (‘gives-up’) it’s heat it contracts and cools down and turns back into a liquid. Once it’s cold enough it can then absorb more heat from outside again and begin the process over.
There are two main types of heat pumps: An air source heat pump and a ground or water source heat pump….
- Ground & water source heat pumps: A ground or water source heat pump system (GSHP, WSHP), is where the heat is stored in an external source environment (ground/earth, pond, well, reservoir, etc..), and by means of distribution pipework is connected thermally via a heat exchanger to the heat-pump system where the source heat is transferred (‘given-up’) to the cold liquid refrigerant to start the cycle above.
- An air source heat pump: Effectively does the same thing by using air as the heat source. It transfers heat from the outside air by blowing it across the heat exchanger where it ‘gives-up’ its heat energy to the cold refrigerant, and likewise starts the cycle above.
FAQs:
What properties are they suitable for?
Anywhere that needs space heating.
However, the output temperature from a typical heat-pump is lower than of a standard space heating boiler. This means existing radiator systems and domestic hot water systems may not be directly compatible, making retrofitting a heat-pump more of a challenge.
Do they require a lot of maintenance?
It is recommended to have at annual service, which is no more than for a gas boiler.
Do heat pumps still work in cold weather?
They have to work harder in cold weather but are still far more efficient than other heating systems. Depending on the system installed they can continue to work as low as -25 °C although most have a limit of -10 °C
Do I need planning permission to install a heat pump?
In a non-domestic building installing a ground or water source heat pump is likely to be considered ‘permitted developed’ so long as certain conditions are met. However, air source heat pump installations on non-domestic land are likely to require planning permission. It is advised to check the specific requirement with your Local Planning Authority.
Normally all types of heat pumps on domestic properties do not require planning permission but in some circumstances, they do; again it is advised to check the planning guidelines within your planning region.
How much do they cost?
Costs vary depending on many factors including the type of system, size of your property, and how much work is needed to adapt existing systems.
There is currently a grant within England and Wales from which you can get up to £7500 of government funding towards a heat pump.
Can you use a heat pump to heat hot water?
It is possible but heat pumps do not heat the water to a high enough temperature to kill legionella, and thus will require supplementary design measures to address this. You can read more information here.
Are they expensive to run?
This can be a tricky question to answer as its very much dependent on the fuel prices, but also many other factors including the efficiency of the system you are installing and the one you are replacing, your location and the average air and ground temperatures. When comparing to an electric heating system, the efficiency savings will likely result in lower running costs. As gas is currently cheaper than electricity when comparing it to gas systems they can be more expensive to run, but a well fitted system can comparable running costs. When comparing to oil the Heat Pump Association advises that a heat pump should offer lower running costs.
For more FAQ and in-depth guides to heat pumps see the https://energysavingtrust.org.uk/advice/in-depth-guide-to-heat-pumps/
If you are keen to find out if you could be saving money can carbon emissions from heat pumps or other renewable technologies get in touch! We are currently offering Suffolk-based businesses a FREE Net Zero advice service. For more information email netszerosuffolk@groundwork.org.uk or head to our webpage.
