Why an Air Source Heat Pump Is a Top Green Home Solution
An air source heat pump can provide efficient heating and cooling solutions for your home in any climate. This green home solution converts solar energy stored in the air into energy, providing heat for domestic purposes.
Domestic air source heat pumps are affordable and are becoming increasingly popular among individual households. The total cost of installing an air source heat pump ranges from £7,000 to 11,000. These costs depend on many factors, including:
- The size of your home.
- How well insulated your home is.
- The brand of the pump.
- The pump size.
- The performance/efficiency of the pump.
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How Does an Air Source Heat Pump Work?
Air source heat pumps (also known as ASHPs) use a natural source of heat - air - to produce energy. They absorb warmth from the outside air and convert it into heat.
Depending on whether you purchased an air-to-air or air-to-water heat pump, the heat that is produced can be used for an underfloor heating system, radiators, warm air convectors and to heat water. An air source heat pump can also be used as an air conditioner.
There are two main types of air source heat pump systems:
- Air to water heat pump: this type of air source heat pump distributes heat via a wet central heating system. This type of system is able to heat your space while also providing hot water.
- Air to air heat pump: this type of air source heat pump system produces heat by using fans to circulate outside air into your home. With this type of heat pump, only space heating is possible, unless combined with another heating system, such as a boiler or similar system.
Air source heat pumps are said to be more efficient in warmer climates, however, this does not mean that they are not cost-effective in colder climates. An air source heat pump, just as a thermodynamic water heating system, can get heat from the air even when the temperature outside drops down to around minus 20 degrees Celsius.
Air source heat pumps have some impact on the environment, as they require electricity in order to run. However, they extract heat from the air, which is constantly being renewed naturally. This makes them an environmentally friendly and green solution nevertheless.
If you would like to have an even lower impact on the environment and lower running costs, you should think about combining your air source heat pump with a solar panel system to generate the electricity for the pump to run.
The Pros and Cons of an Air Source Heat Pump
Investing in an air source heat pump can be beneficial, as they have many advantages, such as:
- Reasonable capital costs.
- The ease with which air source heat pumps are installed (both air to air and air to water).
- Low carbon emissions.
- High efficiency. With an average COP of 3.2, air source heat pumps perform well without wasting energy.
- Low running costs, meaning lower energy bills.
In addition, when purchasing an air to water heat pump, you are eligible for the government's Renewable Heat Incentive scheme (RHI). You can read more about the RHI scheme in our “Grants” section.
However, there are also some disadvantages that should be considered:
- The risk of ice forming when condensed air produces water that freezes at low temperatures. When this happens, the heat flow can be interrupted.
- The outdoor fan can be somewhat noisy. However, the higher the quality of the pump, the more silent it will likely be.
- The maximum temperature of the water from the taps tends to be lower than that of tap water heated with traditional systems.
- When a heat pump is not the right size or strength to meet the needs of the household, the efficiency will be negatively affected.
Many of the downsides above can be prevented by having professional installers to plan and install the air source heat pump system. Keep in mind that you will need to take proper care of your heat pump. Keeping up with maintenance will ensure that the efficiency stays up to par. A pump that is well taken care of can produce up to 25% more energy. Maintenance takes time and is costly, but it is worth it as it will keep your running costs low.
Air Source Heat Pump Prices
Air source heat pump prices range between £7,000 to 11,000. This wide range in price is due to the fact that there are different types of air source heat pumps (air to air and air to water), many brands, and varying sizes and performance strengths that all determine the price.
When you invest in a heat pump system, in this case, an air source heat pump, you have to take into account installation and possible home altering costs.
It is difficult to predict the installation and running costs of an air source heat pump. These will vary depending on many factors, like the size of your home, how well insulated it is, and what room temperature you are aiming to achieve.
An air source heat pump is both efficient and affordable. It is slightly more expensive than a condensing boiler, however, when it comes to heat pump types, air source heat pumps are less expensive than ground source heat pumps. The starting price of an air source heat pump is 50% cheaper than that of a ground source heat pump.
Financing a Heat Pump System with a Grant
If you decide to buy an air source heat pump, you are eligible to receive some government support in the form of a grant. The specific grant you can apply for is the Renewable Heat Incentive (RHI). Keep in mind that in order to be eligible for this grant, the air source heat pump has to be an air-to-water heat pump.
This incentive was established April 9th, 2014 to help the UK government meet environmental goals and targets through the support of domestic consumers of renewable energy sources. If you are a homeowner, landlord, or homebuilder you can apply for this incentive. Visit the UK Government website for more detailed information.
The government announced some changes with regards to the Renewable Heat Incentive. They are as follows:
- A Green Deal Assessment, to determine what the suited efficiency measures are for your home, is no longer needed.
- There is an 183-day occupancy rule that states that in order for people to apply for the RHI scheme they have to reside in the property for 183 days (out of 12 months). However, this rule does not apply for owners of new self-build properties.
- Annual tariff adjustments were being made according to the Retail Prices Index to match the payments to the inflation. Starting April 2016 the RPI will be replaced with the Consumer Price Index to determine the new tariffs.
- The changes ensure that the RHI scheme will take the criteria of the Renewables Obligation (2009, 2015) into account.
- Small administrative changes have been put in place to help the incentive process run in a more efficient manner.
More in-depth information can be found on the UK Government website.
A scenario: RHI Scheme Earnings
If you replace a current heating system, likely a boiler in the UK, with an air to water heat pump, you are eligible for the RHI scheme.
The numbers below represent how much the annual RHI payment would be when replacing a heating solution to an air to water heat pump. The calculations are based on an average sized four-bedroom detached home (England) built between 1900 to 2002. The roof in this scenario would be a loft (pitched and made out of slates or tiles) with unknown insulation and a cavity brick wall that might be insulated.
|Previous heating system||RHI income per year|
|Electric (old storage heaters)||£580|
These calculations were updated in August 2016. If you would like more specific figures for your home, you can easily do the calculations yourself.
How Much Can You Save With an Air Source Heat Pump?
If you purchase an air source heat pump you will be able to save energy as well as money. This is due to the efficiency levels at which air source heat pumps produce energy. You could save up to £1,335.
High Efficiency Means Saving Money
The efficiency of an air source heat pump is measured by the Coefficient of Performance (COP). This refers to the maximum efficiency with which the heat pump can run. Most air source heat pumps have a COP between 2 to 4, but in some cases, it can be as high as 5.
The COP refers to how many kilowatts of heat 1 kilowatt of electricity can produce. An air source heat pump with a COP of 4 will produce 4 kilowatts of heat. Meaning the heat pump will provide you with four times more heat than if you would heat your home using electricity.
If the temperatures outside of a house are around 7 degrees Celsius, the average air source heat pump will have a COP of 3.2. In most parts of the UK, the average temperature is between 5 - 8 degrees Celsius. This means an air source heat pump will generally perform quite well in the UK.
In order to save money, the efficiency of your green home solution is very important. Efficiency is one of the aspects that determines the running costs. Two other key players when it comes to running costs are:
- The amount of heat needed in your home.
- The temperature your source of energy can generate.
A Scenario: Running Costs Savings
In our example, we will look at how much energy is generally needed and used, and how much a household consisting of four people will spend on running costs. We will look at a detached house that is 200m2.
A house that is 200 m2 will most likely need around 11,000 kWh for heat and 4,000 kWh for hot water.
The running costs of an air source heat pump for a three bedroom house are approximately £750. For a detached house, like the one from our main example, the running costs would be around £975. Now compare this to your current energy bill.
The average running cost of a condensing boiler in a 200 m2 house, with an efficiency of 85%, is £1005. For a boiler it isb £1615.
An average home in the UK is around 76 m2. Meaning that for most houses the running costs will most likely be lower than the ones from our example.
How Do Air Source Heat Pump Systems Work?
Air source heat pumps work much like refrigerators. Heat from the air is gathered and absorbed into a loop with refrigerant fluid. After the energy, or rather the heat is extracted from the air it passes through a compressor. The compressor does as it sounds; it compresses, which results in a higher temperature.
Another important part of the air source heat pump is the heat exchanger, which transfers the heat through piping to the needed locations such as radiators, underfloor heating systems and in the case of an air to water heat pump, to hot water circuits in the house.
As mentioned earlier, air to air heat pumps only provide space heating. However, when combined with other heating systems, for example, a boiler, the produced heat can be used to heat water.
Air to air heat pumps generate energy by moving air from one place to another. This process requires electricity. During the warmer seasons, heat gets extracted from the inside, and this warm air will then be released outside, leaving the inside of the house cooler. In this case, the heat pump functions as an air conditioner.
During the cooler seasons, the pump takes air from the outside. The pump presses the air together, a process that heats the air. The warmer air will then be released inside the house and distributed through the pipes to the radiators, underfloor heating or is used to heat water.
Air to water heat pumps work in more or less the same manner. However, the difference is that the heat gets transported to the intended destinations through water piping. An air to water heat pump works based on hydronic technology and functions like a boiler when it is supposed to provide a home with heat and hot water.
Considering an Air Source Heat Pump?
Before you take the step of buying an air source heat pump, it would be smart to consider your current situation and the possibility of implementing changes.
The first factor you should think about is space. Air source heat pumps need some space for the outdoor module, which is placed either on a wall or directly on the ground. What is important, is that the system needs some space around it in order to create a good flow of air. Therefore, placing an air source heat pump near a sunny wall is preferable.
Secondly, you need to consider if your home is well insulated. Heat pumps will function better when a home is well insulated. It is important to add proper insulation and draught-proofing to the home to reach the highest level of efficiency for your air source heat pump.
Next, you need to think about the current energy source and the fuel it uses. If your home currently uses electricity or coal to fuel your heating system, an air source heat pump will pay for itself much quicker.
You might also want to think about the heating systems that are part of your home. Purchasing an air to water heat pump can be more beneficial if it's used with an underfloor heating system or warm air heating, because of the lower water temperatures needed.
Finally, you should think about options to complement the air source heat system. Combining an air source heat pump system with other building work could reduce the costs of installing the system.
Combining an air source heat pump with other green home solutions will also greatly benefit you. A secondary system will be able to function as a backup or boost the performance of the heat pump. Although not necessary, you can combine an air source heat pump with a condensing boiler.
As mentioned before, it is also a good idea to combine an air source heat pump with a solar panel system. The heat pump will run on the electricity provided by the solar panels.
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