The heat pump grant
With the news that the government’s homeowner’s heat pump grant has been increased to £7,500, we take a look at why heat pumps lower pollution and energy bills.
Heat pumps emit far less pollution than gas boilers and can lower bills, but they are expensive to buy – the government is hoping that the scheme will lower the cost of installing a new heat pump, in line with that of a gas boiler.
There are 27 million old gas and oil boilers and the aim is to replace 600,000 a year, but the current rate is only 27,000 per year.
Heat pumps are 3 to 4x more efficient than conventional systems. They require very little maintenance and can be installed in existing and new build properties.
Designed correctly, a heat pump will give you heating and hot water all year round - even in temperatures below freezing.
There are great benefits to installing a heat pump in your home:
- Heat pumps are highly energy efficient: for every unit of energy you put in, you get three to four units of heat out of a heat pump. This means that they require less energy to produce heat for your home. Combined with proper insulation, this can lead to lower energy bills and a reduced carbon footprint.
- Heat pumps lower emissions: as heat pumps use renewable energy sources, they produce lower carbon emissions than traditional heating systems. This is good news for the environment - it helps to reduce the impact of climate change.
- Heat pumps have a longer lifespan: heat pumps typically last up to 20 years or more (with proper maintenance).
- Heat pump fitting: modern heat pumps can be fitted in most properties under permitted development. (An air source heat pump is about the same size as an air conditioning unit).
The different types of heat pump
Heat pumps are not a new technology, in fact they were invented in the 1850s and have been used in homes since the 1960s.
An Air Source Heat Pump is based on a simple principle: it uses a small amount of energy to transfer low grade heat by drawing heat from the outside air. The heat goes through a compressor that creates a high-grade heat, which is then used to meet the heating and hot water demands of your home or building.
The second main type of heat pump draws heat from the ground. Ground Source Heat Pumps let you tap the natural heat energy in the ground (geothermal energy), to provide central heating and hot water for your home.
The heat pump cycle
A heat pump gathers heat from one place and puts it in another place. Many heat pumps can be run in reverse, either heating or cooling, depending on what’s needed.
They key element to a heat pump is the refrigerant: a fluid that moves in a circuit, soaking up and releasing heat as it goes. Electricity powers the system, pushing the refrigerant around the cycle. As the refrigerant moves through the heat pump, it’s compressed and expanded, switching between liquid and gas forms to allow it to gather and release heat at different points in the cycle.
Heat pump refrigerants have very low boiling points, typically below -15 °F (-25 °C). At the start of the cycle, the refrigerant is around that temperature - in liquid form. In the first stage, the refrigerant flows through a heat exchanger, past the outside air and warms up enough to start boiling, changing from a liquid to a gas.
The second phase of its journey is a trip through the compressor which squeezes the refrigerant into a smaller volume, increasing its pressure and boiling point, and warming it further. By the time the refrigerant is past the compressor, it’s warmer than the room indoors.
The third leg of the refrigerant’s cycle takes it through another heat exchanger. By now, the refrigerant is a warm gas, above 100 °F, and it’s flowing past a relatively colder room. As it transfers some of that heat into the room - with the help of a fan - it starts turning back into a liquid.
In the fourth stage, the liquid refrigerant goes through an expansion valve, releasing the pressure. Just as squeezing a material heats it up, expanding it allows it to cool down again, so now the liquid is back to a low temperature and ready to absorb more heat to bring inside.
Are heat pumps installed globally?
Yes, for example, there are heat pumps running throughout the US, and about 60% of buildings in Norway are heated with heat pumps, along with 40% in Sweden and Finland.
Over 30 countries around the world have incentive programs for heat pumps. Italy has especially generous subsidies for heat pumps that are installed when retrofitting buildings for energy efficiency, with customers getting up to 110% of the purchase price back as a tax credit.
The future for heat pump technology
Over the last ten years, most of the heat pumps that were installed globally have relied on F-gas refrigerants, mostly R410a with a greenhouse gas potency 2,100 times higher than CO2 over a 20-year span. These hydrofluorocarbons leak, which is why the European Commission wants to ban them.
Better, cleaner heat pumps are on the horizon, which are able to replace a gas boiler without the need to take away existing radiators.
The coming generation uses CO2 or helium as the working medium instead of F-gases. Helium pumps promise much higher temperatures while retaining the same conversion of one unit of electricity into three to four units of heat.
BlueHeart Energy, in the Netherlands, says that its compact thermo-acoustic heat pump can drop in as a direct replacement for gas boilers, and reach temperatures high enough for existing radiators in old homes that have bad insulation.
France’s research institute (CNRS) is working with natural rubber that heats up when it is stretched, and cools as it compresses.
Heat pumps are a great option for homeowners in the UK who are looking for an energy-efficient and environmentally friendly way to heat their homes. The long-term energy savings and reduced carbon footprint make them a very worthwhile investment, in our opinion.
Carl Dodd, Property Revolutions Ltd.
