Air Source Heat Pump

What are Air Source Heat Pumps and how much can they save you?

What is an Air Source Heat Pump?

An Air Source Heat Pump is one of the most commonly used and simplest of heat pumps to install and can provide an efficient renewable energy solution to heating your property, pool or hot water. They take heat from the outside air and pump it across refrigerant-filled coils that generate super-heated gases for the purpose of heating water to high temperatures, either for hot water use or space heating, through a radiator or underfloor heating system.

Even on the coldest day an Air Source Heat Pump can harvest renewable heat energy from the outdoor air and transfer it inside the home. Often placed at the ground level of an exterior wall, an Air Source Heat Pump runs quietly and works at temperatures as low as -25c¹.

The entire process is highly efficient and can provide cheap, reliable hot water and central heating for your home for the life cycle of the pump, which is in excess of twenty years².

Air Source Heat Pump Efficiency

The efficiency of an Air Source Heat Pump is referred to as the Coefficient of Performance or CoP. This is the ratio between heat delivered and power consumed which will vary throughout the year depending on the outside temperature. The average UK winter heating temperature has an average CoP of 3.4:1, providing 3.4 units of heat for each unit of energy consumed, resulting in significant energy savings.

How Does an Air Source Heat Pump Work?

Whereas traditional fossil fuel boiler systems work by producing on-off bursts of heat to maintain the desired room temperature, an Air Source Heat Pump will work much more efficiently by supplying hot water to the radiators at a lower yet more constant temperature. This will give you a controlled level of year-round warmth and all of the hot water you need.

An Air Source Heat Pump is based on one simple principle, heat transfer – using a small amount of energy to transfer low-grade heat from the air to high-grade heat, heating water to high temperatures. Essentially transferring heat from a ‘free heat source’ like the air to a ‘heat sink’ like your home.

This is a similar operation to a refrigerator – but in reverse and is a process known as the vapour compression cycle.

1. The refrigerant inside the coils begins as a cold low pressure liquid.

2. As the refrigerant passes into the evaporator, warm air from the outside air passes over the evaporator as well. This causes the refrigerant to increase in temperature, due to its low boiling temperature and change to a hot gas.

3. This hot refrigerant gas then enters the compressor where its temperature increases further as a result of the compression process – much like a bicycle pump heats up during its use.

4. The hot refrigerant gas is then condensed as it passes across one side of a plate heat exchanger, at which point, the heat is transferred to the cooler side (water side) of the heat exchanger. This, now high-temperature water, is distributed via the buildings heating circuit.

5. As the temperature of the refrigerant decreases its state changes from a gas back to a cool liquid.

6. Despite dropping in temperature, the cool liquid still has a high pressure which must be reduced. To reduce this pressure the liquid refrigerant passes through an expansion valve causing the pressure to drop and the temperature to lower further. This process returns the refrigerant to its initial state of cool low pressure liquid.

7. This process is repeated to provide a constant temperature to the property.

In summary, as the high temperature gasses pass the heat exchanger, the heat is transferred to create hot water capable of heating the property as well as providing hot water.

Frequently Asked Questions

Air Source Heat Pumps can reduce your annual heating and hot water bills by up to 50%³ against fossil fuel alternatives and it often pays for itself within the grant period set out within the Renewable Heat Incentive (7 years of payments for a domestic property).

However, each and every property is different so upfront cost, bill reduction and your ROI is never going to be a one answer fits all. The best way to find out how much an Air Source Heat Pump can reduce your heating and hot water bills is to speak to us directly for a free, no obligation quote.

What is the Renewable Heat Incentive?

The RHI is a Government backed scheme which pays the owner of a renewable technology, such as a heat pump, for generating renewable energy on site. To qualify for these quarterly payments, which last seven years, you will need to use an MCS accredited company – such as Ecovision – and ensure your MCS accredited product is installed to MCS standards.

The MCS (Microgeneration Certification Scheme) is there to ensure the system is safely installed by professionally qualified installers and performs to the standards required by the Government.

Learn more about the Renewable Heat Incentive here…

How do I apply for the Renewable Heat Incentive?

The RHI is administered by Ofgem and as the owner of the system, you will need to make the application for the RHI. We will of course ensure you have all the required paperwork to successfully complete this; this is supplied as part of your handover pack and we will be on hand to help at any point throughout the process.

Learn more about the applying to the Renewable Heat Incentive here…

Or make your RHI application directly here…

Will an Air Source Heat Pump work with my existing radiators?

Ecovision will have to complete a full room-by-room emitter (radiator) assessment before any installation takes place to ensure your existing radiator circuit is capable of emitting the heat required. This a government requirement in order to be eligible for the RHI subsidy.

We usually find that most of the radiators are suitable but that some will need to be changed to meet the government’s accreditation standards. These changes will ensure the lowest possible running costs and the cost of any changes will be made clear in your quotation.

How big is an Air Source Heat Pump?

The heat pump will be positioned externally and will be approximately 1,000mm wide and between 740 to 1350mm tall. The depth of the unit is 330mm, but you will need to allow 300mm behind and 1,000mm in front of the unit.

We will locate the cylinder internally, usually in the same location of your current cylinder. The controls are typically mounted on the cylinder or nearby and are similar in size to that of a shoe box.

How long do Air Source Heat Pumps take to install?

On average Ecovision can fully install an Air Source Heat Pump in less than 4 days and, if required, we can partially replace or install a complete radiator or underfloor heating system.

Can I change the temperature within my home?

The heat pump will be weather compensated which means that you set the temperature you want within your home and the heat pump uses the least amount of electricity required to achieve the desired temperature.

As the outside temperature reduces, or indeed increases, the heat pump will automatically react and adjust its output to maintain your chosen internal temperature. It does this via a range of sensors strategically placed within the system – you simply set your desired temperature and let the heat pump do the rest.

Our customers often report an improvement in comfort levels as the heat pump maintains a constant temperature rather than allowing the internal temperature to fluctuate based upon a traditional time clock.

Will an Air Source Heat Pump keep me warm in winter?

Yes, the system will be capable of providing all of your heating and hot water throughout the year without any requirement for a supplementary boiler. They can provide up to 4 times as much heat as an electric heater using the same amount of energy.

Do I need to coordinate any other trades on site?

No, Ecovision can undertake the entire installation, providing the complete design, supply, installation and commissioning of the system, without any need for third parties or subcontractors.

During Ecovision’s many years of business we have found that the biggest issue for customers is ensuring that everyone knows what and when their responsibility starts and ends. We have found that by offering the complete installation we ensure that we remain in control of the whole process as well as being entirely responsible for the successful completion of the installation with our in-house installers reporting directly to Ecovision.

Does an Air Source Heat Pump make a lot of noise?

An Air Source Heat Pump will make some noise when they are operating, as a compressor and fan are in motion, however, this noise can be far less than you may think. Before an Air Source Heat Pump can be installed they must pass a noise assessment, ensuring you never hear the Heat Pump from inside your property. Furthermore, with a decibel rating similar to, or less than, that of a conventional boiler, your neighbours shouldn’t even know it’s there.

Does an Air Source Heat Pump require lots of maintenance?

Generally, Air Source Heat Pumps require very little maintenance, as they are a sealed unit, much like your fridge. Though it is recommended that you inspect and clean your Air Source Heat Pump annually, clearing any build-up of leaves or debris from behind the unit.

Ecovision can complete this task as part of an annual service, leaving you with absolutely no maintenance requirements.

¹Heating range based on a 14 kW NIBE F2300 Air Source Heat Pump ( Other manufacturers report similar ranges.

²Age of System Source: Energy Saving Trust. Please note that these figures may be more or less achievable depending on manufacturer.

³Energy savings based on replacing an existing G-rated oil or LPG boiler with a Mitsubishi Ecodan 8.5kW Air Source Heat Pump (

Potential earnings of over £9,000 in RHI payments for installing an Air Source Heat Pump based on a 3+ bed detatched house (  RHI payments are based on the annual estimated payments in the potential earnings over the seven-year period.  You can also earn an additional £1,610 over 7 years when you install a Domestic MMSP monitoring system (