Boiler Guide

Air Source Heat Pump

Renewable heating that extracts warmth from outdoor air.

An air source heat pump (ASHP) extracts heat energy from outdoor air — even in cold weather — and uses it to heat your home and hot water. Heat pumps do not burn fuel; instead they move heat, making them highly energy-efficient and low-carbon when powered by renewable electricity.

Typical Cost

£8,000–£15,000 installed (before £7,500 Boiler Upgrade Scheme grant)

Install Time

2–3 days

Efficiency

CoP of 2.5–4.0 (250–400% efficient in energy output terms)

How Does a Air Source Heat Pump Work?

A heat pump works like a refrigerator in reverse. A refrigerant fluid circulates through an outdoor unit, where it absorbs heat from the air. The refrigerant is then compressed, which increases its temperature. This heat is transferred indoors to heat water for your underfloor heating, radiators, or hot water cylinder. The process can produce 2.5–4 units of heat for every unit of electricity consumed.

Pros & Cons

✓ Advantages

✓Very low carbon emissions — no on-site fossil fuel combustion
✓Highly efficient — Coefficient of Performance (CoP) of 2.5–4.0
✓Eligible for the UK Boiler Upgrade Scheme (£7,500 government grant)
✓Can provide both heating and cooling
✓Low maintenance compared to gas boilers
✓No flue required

✕ Disadvantages

✕High upfront installation cost
✕Works best with underfloor heating or large low-temperature radiators
✕Less efficient in very cold weather (though modern units work down to -20°C)
✕Outdoor unit requires adequate space and airflow
✕May require home insulation upgrades to work efficiently
✕Hot water temperature is typically lower than a gas boiler (around 55°C vs 65°C+)

Best For

→Well-insulated homes — particularly newer builds or post-retrofit properties
→Homes with underfloor heating or oversized radiators
→Properties off the gas grid looking for a renewable alternative to oil or LPG
→Environmentally-conscious homeowners
→Properties eligible for the Boiler Upgrade Scheme grant

Not Ideal For

✕Poorly insulated older properties without planned insulation upgrades
✕Homes with a high-temperature radiator system that cannot be upgraded
✕Properties where upfront cost is the primary constraint

What Is an Air Source Heat Pump?

An air source heat pump (ASHP) is a low-carbon heating technology that extracts thermal energy from outdoor air and uses it to heat your home and hot water. Rather than burning fuel to generate heat, a heat pump moves existing heat — making it far more energy-efficient than any combustion-based system. For every unit of electricity it consumes, a modern heat pump can deliver 2.5 to 4 units of usable heat.

How Does an Air Source Heat Pump Work?

The process is similar to how a refrigerator or air conditioning system works, but in reverse. An outdoor unit contains a fan and a heat exchanger filled with refrigerant. Even in cold winter air, there is thermal energy available — the refrigerant absorbs this and vaporises. The refrigerant is then compressed by a pump, which raises its temperature significantly. Inside the home, this heat is transferred to your heating and hot water system via a second heat exchanger. The refrigerant then returns to its liquid state and the cycle repeats.

Heat Pumps and UK Homes

Heat pumps work best at lower flow temperatures than traditional gas boilers. This means they are most efficient in well-insulated homes with underfloor heating or large, modern low-temperature radiators. Many older UK homes can be adapted to work well with heat pumps, but a fabric-first approach — improving insulation and draught-proofing before installation — will maximise performance and minimise running costs.

The Boiler Upgrade Scheme

The UK government's Boiler Upgrade Scheme currently offers a £7,500 grant towards the cost of installing an air source heat pump. This significantly reduces the upfront cost for eligible properties. Our team can advise on eligibility and guide you through the application process.

Air Source Heat Pump Installation in Northamptonshire

Corby Boiler Installations installs air source heat pumps from leading manufacturers including Mitsubishi Electric, Daikin, and Vaillant. Our MCS-accredited engineers cover Corby, Kettering, Northampton, and the wider region.

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