Heat Pump Systems

What is a Heat Pump?

A heat pump is a machine that extracts heat from one place and transfers it to another. The heat pump is not a new technology; it has been used in fridges since the early 1800's. Refrigerators and air conditioners are both common examples of heat pumps. Heat pumps transfer heat by circulating a substance called a refrigerant through a cycle of alternating evaporation and condensation. A compressor pumps the refrigerant between two heat exchangers. In one heat exchanger, the evaporator, the refrigerant is evaporated at low pressure and absorbs heat from its surroundings. The refrigerant is then compressed en-route to the heat exchanger, the condenser, where it condenses at high pressure. At this point, it releases the free heat it absorbed earlier in the cycle. The heat from the fluid is transferred to the water in your heating system, including radiators and underfloor heating, as well as your hot water tank.

There are three main types of Heat Pumps:

  1. Air Source heat Pumps - The air source heat pump needs to be located outside in the open air, and uses a fan to draw air into it. This air then flows over a heat exchanger, which contains a refrigerant liquid. An evaporator uses the latent heat from the air to heat the refrigerant liquid sufficiently until it boils and turns to a gas. This gas is then compressed by a compressor, which causes it to significantly increase in temperature. An additional heat exchanger removes the heat from the refrigerant (turning it back to a liquid), which can then be used as useful heat.
  2. Ground/Water Source Heat Pump - A ground source heat pump system uses heat trapped beneath the ground and boosts it to a higher temperature using a heat pump. This heat is then used to provide home heating or hot water. The heat pump performs the same role as a boiler does in a central heating system, but uses ambient heat from the ground rather than burning fuel to generate heat. This may also be known as Geothermal Heat.
  3. Exhaust Air Heat Pumps - An exhaust air heat pump extracts air via ventilation ducts positioned in the wet rooms of the house such as bath rooms, kitchens and utility rooms. These heat pumps are build houses or new apartments where they have been designed with the necessary ventilation system and should not be retrofitted.

See the Electric Ireland Heat Pump Video for more information.

Why is it called a heat pump?

When in operation, a heat pump system is constantly pumping heat. That’s the beauty of the system that drives a heat pump. In the summer, a heat pump moves heat from the inside of your home to the outside. During the cold winter months, heat is moved from the air outside your home to the inside. This is accomplished by utilizing the refrigerant that is pumped by the compressor through both the indoor and outdoor air coils.

Where can I collect free energy from outdoors for my heat pump?

There are various energy sources that can be used with a heat pump:

  • Vertical collectors: which involves drilling holes vertically into the ground and extracting heat from deep down. The pipework can either be laid horizontally or vertically. If laid horizontally, the pipework tends to be buried in trenches 2-3m deep, spread over a huge surface area to ensure the heat transfer liquid has the opportunity to increase to a sufficient temperature. If the pipework is installed vertically, boreholes get drilled into ground at a cost of €6,000 – €8,000 per borehole. These need to be drilled by professionals and will regularly exceed 100m in depth to ensure that the heat transfer liquid has the opportunity to absorb enough heat.
  • Horizontal collectors: these take up large amounts of area where pipes are buried under the ground to take advantage of solar energy stored in the ground. These collectors can also use lakes and rivers to act as an energy source.
  • Air: It is also possible to use ambient air temperature to collect heat as well as exhaust air. This system works in a similar manner to geothermal heat pumps except heat is extracted from the air as opposed to the ground. This is very suitable to Irish conditions due to our moderate winter temperatures.

What is the Seasonal Performance Factor (SPF)?

The seasonal performance factor of a heat pump is how much heat energy is generated using one unit of electricity over the course of a year. The higher the SPF, the more heat is generated for the same unit of electricity. Usually, air source heat pumps are around 3, water source heat pumps around 3.5 and ground source heat pumps around 4. The reason for the change is the difference in temperature witnessed in each heat source over the seasons. So the outside air temperature falls just when the air source heat pump needs to be providing the most heat, whereas the ground stays at much more of a constant temperature, meaning that the ground source heat pump doesn’t have to use as much electricity to reach the same temperature.

Can heat Pumps provide Hot Water for showers and baths?

A heat pump can do everything a traditional fossil fuel boiler can, including provide domestic hot water. Heat pumps usually use an unvented hot water cylinder to store water at between 50⁰C and 65⁰C, depending on the heat pump model. All the hot water you need is provided by the heat pump's compressor process – and although there is an immersion fitted in many models (or in our cylinders) for back-up and functions such as temporary extra hot water for additional guests or legionella protection, the compressor is normally all you use.

Do I need to service my heat pump and how much maintenance is required?

Heat Pumps should last for 15 - 20 years and generally come with a 3 - 7 year warranty. A heat pump system will benefit from annual servicing to ensure that all the mechanical connections are sound, settings are at their optimum and that the heat collector is working properly. Regular professional servicing may also be required to validate extended warranties, this varies from manufacture to manufacture. Depending on the make and model of heat pump you may be able to complete some of the filter cleaning activities to ensure your heat pump continues to perform efficiently.

How much noise does the heat pump make?

The outdoor part of the air source heat pump system does have a fan which draws the air across the internal components and this will make a whirring noise during operation. The amount of noise depends on the quality of the product. Modern air source heat pumps are extremely quiet and should not provide any disturbance to you or your neighbours if installed properly. The internal unit will have a noise level similar to a domestic fridge or dishwasher and certainly wouldn’t be noticed in a utility room. There is no need for a separate shed or garage.

Can air source heat pumps still deliver heat to your home in winter?

It might seem impossible, but most air source heat pumps can still deliver heat to your home when outdoor temperatures are as cold as -20⁰C.

Can I remotely control and read heat pump settings using smart controls?

Yes. A lot of heat pump manufactures have their own smart control system to support their heat pump. Depending on the manufacture, smart remote access to your heating system will let you control settings and temperature via website and optional controllers. You may also be able to download an app to your phone or tablet. These smart controls will allow you to see how much energy you are using, allowing you to spot trends and vary your heating to match your needs with maximum efficiency and minimum cost. These advanced controls also mean that both service engineers and your installers can access your system remotely to check your system is running as efficiently as possible and troubleshooting if ever necessary. Heat Pump Controls are also easy to use. Simple controls allow you to easily adjust the temperature, so that it’s never too hot or too cold.

Can I link solar panels to the heat pump?

Solar PV and Solar Thermal Systems can be integrated to work with your heat pump system depending on the make and model of your heat pump.

Can a heat pump cool my home in the summer?

Certain types of heat pumps offer the ability to provide cooling when needed.

Are Heat Pumps Environmentally Friendly?

Yes, heat pumps are officially classed as providers of renewable energy by the EU and the International Energy Agency. Using a heat pump will therefore be an easy way usually of complying with your needs for renewables in a new build for Part L regulations provided that the house is well insulated, and the system works well.

What is the cost of installing a Heat Pump System and are there any grants?

Air source heat pump installations usually cost between €8,500 and €14,500, depending on the size and power of the heat pump, how much hot water storage you require and whether you want the heat pump to be controllable over the internet. Ground source systems range from €12,500 to €23,500, again depending on the size of heat pump, hot water cylinder and ground loop system.

The SEAI currently offer a grant of €3,500 towards the cost of installing a heat pump system in homes built before 2011. To further support this Electric Ireland offer energy credits towards your electricity bill of up to €1,019.20 depending on what type of heat pump is installed through The Energy Efficiency Incentive.

To further reduce the cost of heating your home an All Electric Tariff is available. This price plan offers reduced day and night rates for all electricity consumed in homes using heat pump technology.
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