There are many benefits to Air source heat pumps

Unlike conventional boilers there is no carbon produced when in operation.
Air source heat pumps also have incredibly low running costs.


Hybrid Air source heating systems are basically air source heating systems linked with a new high efficiency gas or oil boiler .
This gives the homeowner the benefits of low cost heating but with the back up of a new more efficient boiler only when the heat pump needs that little bit of extra help in the colder conditions .

A heat pump captures heat from outside and moves it into your home. It uses electricity to do this, however the quantity of heat delivered into your home is much greater than the quantity of electricity used to power the system.

As a heat pump captures heat that is already present in the environment, the system itself does not burn any fuel and therefore emits no carbon dioxide.


What is an air source heat pump?

An air source heat pump, sometimes referred to as an air-to-water source heat pump, transfers heat from the outside air to water, which heats your rooms via radiators or underfloor heating. It can also heat water stored in a hot water cylinder for your hot taps, showers and baths.

Heat from the air is absorbed into a fluid. This fluid then passes through a heat exchanger into the heat pump, which raises the temperature and then transfers that heat to water.

Is an air source heat pump right for me?

Air source heat pumps are suitable for many types of homes and are the most common type of domestic heat pump, with tens of thousands of installations across the UK. However, there are a few things you should consider before deciding whether a heat pump is right for you.

  1. The external unit for a heat pump is identical for both monobloc and split heat pumps. Noise is created by large fans moving air across the heat exchanger. Unless the heat pump is working very hard (ie in cold weather or producing high temperature water), you can expect the noise to be a similar volume to a fridge, if you were standing within a couple of metres. You could easily hold a normal conversation next to it, without raising your voice. As it gets colder outside, this noise will increase while it’s operating, but should still allow you to hold a conversation easily, only raising your voice a little. The inside unit for a split system only contains valves and pumps and makes very little noise at all.
  2. Most homes in the UK use radiators or underfloor heating to circulate hot water. If you don’t currently have radiators or underfloor heating, you will have to decide whether you’d like to install them. This is a great opportunity to make sure the system is optimised for a heat pump, resulting in lower running costs.
  3. A standard heat pump doesn’t provide hot water on demand like a combi boiler, so you will need a way of storing hot water for when you need it. The size of hot water cylinder required will depend on the amount of hot water that your household typically uses, but the cylinder can usually be fitted inside any cupboard that measures around 80x80cm. If you don’t have space for a hot water cylinder, you still have options. Some hybrid systems are designed with the heat pump providing heating and a boiler providing hot water on demand. You could also consider installing a heat battery, which takes up less space than a hot water cylinder. Instantaneous hot water heaters are also available and can be installed under your kitchen sink to provide a smaller amount of hot water.

Hybrid heat pumps

A hybrid heat pump is a heating system that combines an air source heat pump with a gas or oil boiler. The oil or gas boiler is used to 'top-up' a low temperature heat pump to meet the heating demands of the property where the heat pump cannot do it alone. Purpose designed hybrid systems can be set to control which heat source comes on when, depending on efficiency or energy cost targets.

How does it work?

Most air source heat pumps work at lower temperatures than our gas or oil fired heating systems; commonly 40-45 degrees C compared with 65-75 degrees C from fossil fuel systems.

Without insulating our homes or upsizing our radiators to run a lower temperatures, low temperature air source heat pumps are unsuitable for existing properties. Some manufacturers have produced heat pumps that can run at higher temperatures of 65 degrees C, but the efficiencies drop. There are many horror stories of heat pumps being wrongly fitted into older homes and failing to heat the home and/or massively increasing electricity bills. .

Hybrid heat pumps let the heat pump run at its happy and efficient temperature of 40 degrees C, which will provide sufficient heat for a large part of the year. As outside temperatures drop, and when hot water is used, the gas or oil boiler can step in to raise the temperate of the water.

A number of hybrid heat pump trials have been undertaken in existing homes to better understand the contribution a heat pump can make to a heating system. The results varied widely, which heat pumps providing between 50% and 80% of heating and hot water supplies in a sample of house types*.

Hybrid v bivalent systems

A hybrid system is a purpose built combined heat pump with oil or gas boiler from the same manufacturer. In this set up, the heat pump can run all or most of the time and the gas or oil boiler tops it up.

A bivalent system is when any heat pump is paired with any gas or oil boiler and combined via a buffer tank. This means you can potentially work with your existing gas or oil boiler if it still in good order. In this set up, the heat pump will run as much as possible when it can meet your demand. When the outside temperature drops below a certain point the heat pump will switch off and the oil boiler will fire. I.e. they do not run at the same time.

Why do we need hybrid heat pumps?

The UK has a legal obligation to be net zero by 2050. As homes account for 20% of greenhouse gases it is important to find ways of reducing our reliance on fossil fuels. Home insulation will form the majority of the works needed to achieve this and in reducing our heat requirement we prepare homes for low temperature air source heat pumps.

However for poorly insulated homes and larger homes, fossil fuels may still have a role to pay in the medium term to provide the higher temperatures needed for conventional radiator systems.

In 2019 the Committee for Climate Change (CCC) identified hybrid heat pumps as vital and fast track way to reduce our consumption of fossil fuels and begin decarbonising UK homes. They urged for the immediate deployment of hybrid heat pumps in large volumes with a target of fitting 10 million by 2035. The CCC continue to emphasise their importance in their recently published Sixth Carbon Budget.

What are the benefits for UK households?

For UK households, hybrid systems offer an opportunity to reduce our gas or oil consumption without waiting for our homes to be insulated or replacing all our radiators. For off-grid homes they can also reduce your running costs. For those on mains gas, providing the heat pump is set to run efficiently, the running costs will be similar to mains gas (depending on the cost of electricity).

Hybrid heat pump manufacturers

There are a few options for homeowners to combine a heat pump with a fossil fuel boiler and in some cases they can keep their existing boiler in place. Alternatively, any heat pump and gas or oil boiler can be combined via a buffer tank.