How Do Air Source Heat Pumps (ASHP) Work?
- Bristol Renewable Heat
- Oct 10
- 3 min read
Introduction: The Future of Home Heating Is Already Here
If you’ve been hearing more about air source heat pumps and wondering how they actually work, you’re not alone. More and more UK homeowners are switching from gas boilers to cleaner, renewable heating systems.
In this simple guide, we’ll explain in plain English how air source heat pumps work, how efficient they are, and whether they could be the right choice for your home.
What Is an Air Source Heat Pump?
An air source heat pump (ASHP) is a low-carbon heating system that takes heat from the air outside your home — even when it’s cold — and uses it to heat your rooms and hot water.
It works a bit like a reverse fridge:
A fridge moves heat out to keep food cold.
A heat pump moves heat in to keep your home warm.
Although they run on electricity, air source heat pumps are three to four times more efficient than standard electric heaters, so you get much more heat for your money.
Step-by-Step: How an Air Source Heat Pump Works
Here’s what happens behind the scenes:
Air Intake:The outdoor unit draws in air and passes it over a coil filled with refrigerant.
Heat Absorption:The refrigerant absorbs heat energy from the air — even when it’s below zero outside.
Compression:The refrigerant is compressed, which increases its temperature.
Heat Exchange:The heat is transferred into your home’s heating system (radiators, underfloor heating, or hot water cylinder).
Distribution:Warm water circulates through your system, keeping your home comfortable and cosy.
Some models can even reverse the process in summer to provide cooling, like an air conditioner.
Efficiency and Running Costs
The efficiency of a heat pump is measured by its Coefficient of Performance (COP) — the amount of heat produced for every unit of electricity used.
A typical UK system has a COP of 3 to 4, which means 1 kWh of electricity produces 3–4 kWh of heat.
Compared with oil or LPG boilers, that can reduce your heating emissions by up to 65%.
Your running costs will depend on:
Your electricity tariff
How well your home is insulated
The quality of the design and installation
With a properly designed system, most homeowners find air source heat pumps to be cost-effective and energy-efficient — especially when used with smart controls or solar panels.
UK Grants and Incentives
Through the government’s Boiler Upgrade Scheme (BUS), homeowners in England and Wales can currently receive a £7,500 grant towards the cost of installing an air source heat pump.
At Bristol Renewable Heat, we’ll help you check your eligibility and manage the application process from start to finish, so you can claim the full amount available.
Are Air Source Heat Pumps Right for Every Home?
Most UK homes can benefit from a heat pump, but these are good signs that yours is ready:
✅ Well-insulated walls and loft
✅ Space for an outdoor unit (around 1m x 1m)
✅ Suitable radiators or underfloor heating
If your home ticks those boxes, you could enjoy lower carbon emissions, reduced energy costs, and a future-proof heating system.
🛠️ Why Expert Installation Matters
A well-installed system makes all the difference. When a heat pump is correctly designed and commissioned, it will perform efficiently, quietly, and reliably.
That’s why choosing a MCS-certified installer like Bristol Renewable Heat is so important. We tailor every system to your property and heating needs — from initial survey to final setup.
Key Takeaways
Air source heat pumps extract renewable heat from the outdoor air.
They’re up to four times more efficient than electric heating.
Grants of up to £7,500 are available under the Boiler Upgrade Scheme.
Ideal for well-insulated UK homes with space for an outdoor unit.
Professional design and installation ensure the best performance.
Thinking About Switching to a Heat Pump?
At Bristol Renewable Heat, we specialise in the design, installation and maintenance of high-performance air source heat pump systems across the South West.
👉 Get a free consultation or quote today and discover how renewable heating could work for your home.
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