Air Source Heat Pumps and Underfloor Heating. What you Need to Know.

For homeowners looking for sustainable, energy-efficient heating solutions, combining an air source heat pump with underfloor heating is a common choice. This powerful pairing has the potential to significantly lower energy bills while improving home comfort and reducing your carbon footprint.

In this guide, we explain how these systems work together, the benefits, costs, and what to consider before installation.

What are heat pumps and underfloor heating?

How do heat pumps work?

Heat pumps are low-carbon heating systems that extract thermal energy from external, natural sources and convert it into usable heat.

Air source heat pumps are the most commonly installed type of heat pump in UK homes. They look a lot like an air conditioning unit, but work in the opposite way, i.e., they draw warmth from the air outside your home, even in cold weather, and compress it to a higher temperature for space and water heating.

Types of heat pumps suitable for homes

• Air Source Heat Pumps (ASHPs): Ideal for most UK homes, especially those without access to mains gas.
• Ground Source Heat Pumps (GSHPs): In the case of GSHPs, pipes are buried underground to draw heat. These systems can be costlier to install and are only suitable for properties with a good amount of outside space.
• Water Source Heat Pumps: These systems are less common in residential heating systems as they need to draw heat from a nearby body of water.

How underfloor heating systems operate

Underfloor heating (UFH) works by circulating warm water through a network of pipes that are installed beneath the floors in a property. This turns your entire floor into a low-temperature radiator, evenly warming the room from the ground up. UFH typically operates at lower temperatures than traditional radiators.

Can heat pumps and underfloor heating work together?

Absolutely. ASHPs alongside UFH are one of the most effective heating combinations available.

Why they are an ideal match

ASHPs and underfloor heating are an ideal pairing because both systems thrive on low-temperature operation. Air source heat pumps are most efficient when delivering heat at lower temperatures, and underfloor heating is specifically designed to make the most of this gentle, steady warmth. When combined, they offer a highly efficient, low-carbon heating solution that can significantly reduce energy bills and improve indoor comfort. This synergy makes them a smart choice for modern, sustainable homes.

Air source heat pumps (ASHPs) are an increasingly popular choice for energy-efficient home heating. They work by extracting heat from the outside air (even in cold weather) and transferring it into your home. The system uses a refrigerant to absorb this ambient heat, which is then compressed to raise its temperature. This heat is passed through a heat exchanger and distributed via your home’s heating system, such as radiators, hot water tanks, or underfloor heating.

Underfloor heating (UFH), especially in its water-based form, is another efficient heating solution. It works by circulating warm water through a network of pipes laid beneath the floor surface. This setup gently radiates heat upward, creating a consistent and comfortable warmth throughout the space. One of its key advantages is that it operates at much lower temperatures than traditional radiators, typically between 30°C and 50°C.

Low flow temperatures and system efficiency

Heat pumps operate most efficiently at low flow temperatures, which aligns perfectly with the design of underfloor heating systems. Unlike radiators that need water to reach temperatures of 60–75°C, UFH systems usually only need water to be heated to 30–45°C.

It’s important to note that while UFH systems don’t get as hot as radiators, they still create a comfortable level of heating for your home as the heat is delivered over a larger surface area.

Operating at lower temperatures reduces the strain on your heat pump and improves its Seasonal Coefficient of Performance (SCOP). This means you get more heat per unit of electricity consumed, which results in lower running costs and greater efficiency.

Surface area and heat distribution benefits

Because UFH covers a large surface area, heat is distributed more evenly across rooms in the home. This eliminates cold spots in your home and improves comfort, especially in open-plan spaces or homes with high ceilings.

Benefits of combining heat pumps with underfloor heating

Improved energy efficiency

Heat pumps work best when supplying water at lower temperatures—typically around 35–45°C. Underfloor heating is designed to deliver even warmth at these lower temperatures, unlike radiators which require much hotter water. This synergy allows the heat pump to run more efficiently, reducing energy consumption and lowering your heating bills.

Lower running costs

Though the upfront cost of installing ASHPs and UFH can be significant, combining these systems often results in lower monthly energy bills, especially when replacing electric or oil heating systems.

Because heat pumps are highly efficient (often delivering 3–4 units of heat for every unit of electricity used), combining them with a low-temperature system like underfloor heating maximizes that efficiency. Over time, this translates into significant savings on energy bills and reduced carbon emissions.

Increased comfort and even heating

Underfloor heating provides a consistent, gentle heat that spreads evenly across the room. There are no cold spots or blasts of hot air, just a comfortable, balanced indoor climate. When powered by a heat pump, this comfort is maintained with minimal environmental impact.

Warm floors make your living spaces more comfortable, particularly during colder months. The consistent, radiant heat improves the overall ambiance and reduces dry air circulation common with radiators.

Reduced carbon emissions

Both systems support the UK’s net-zero goals. Air source heat pumps are powered by electricity, but they produce around three times more heat energy than the electricity they use, making them a greener choice.

Combining a heat pump with underfloor heating is a smart move for anyone looking to reduce their carbon footprint. Heat pumps use renewable energy from the air, and underfloor systems require less energy to maintain warmth, making this duo an environmentally responsible choice for modern homes.

Compatibility with renewable energy

ASHPs are powered by electricity. When powered by free electricity that has been generated by solar panels, this system can further reduce your dependency on the grid, bringing you closer to energy self-sufficiency.

Important considerations before installation

Property suitability and insulation

For ASHPs and UFH to be an effective heating solution, your home must be well insulated. This minimises heat loss (and therefore heating bills) and allows the system to maintain comfortable temperatures more efficiently.

New builds vs retrofitting

• New Builds: It is easier to integrate both a heat pump system and underfloor heating if it is included in the initial planning and building phase.
• Retrofits: It is possible to retrofit heat pumps and underfloor heating in existing properties. However, it is likely to involve lifting floors and improving insulation which could bring additional costs and disruption.

Floor construction types and materials

Whether you are building a new property or making changes to your existing property, it is important to consider the types of flooring that work best with underfloor heating.

UFH works best with concrete or screed floors, which retain and slowly release heat. Timber or suspended floors may need specialist solutions and insulation upgrades.

Heat loss calculations and system design

To ensure that the heating system that is installed will be effective, it needs to be the right size for your property. A system that is too big will be expensive to run and a system that is too small might not be able to heat your home adequately.

Professional installers will carry out room-by-room heat loss calculations to size the heat pump and design the UFH layout correctly.

Costs and financial incentives

Upfront installation costs

• Air Source Heat Pump: The typical installation cost for an air source heat pump is between £11,000 and £16,000, depending on the size and complexity of the installation. After applying the £7,500 Boiler Upgrade Scheme Grant, the total cost is likely to fall between £3,500 and £8,500. For more details, visit Air Source Heat Pump Cost Guide.

• Underfloor Heating: Water-based systems cost £100 to £150 per m², excluding installation. Full home installations can range from £5,000 to £10,000, depending on the size of the property.

Running and maintenance costs

Both systems are relatively low maintenance:

To ensure that your heating pump works efficiently and effectively for as long as possible, it is recommended that the system is serviced professionally on an annual basis.

UFH systems have few moving parts and typically last decades with minimal upkeep.

Government grants and funding options

The Boiler Upgrade Scheme (BUS) in the UK offers grants of up to £7,500 to reduce the cost of installing an air source heat pump. You may also qualify for additional local incentives or green home finance options.

The scheme is available to people in England and Wales who are replacing a fossil fuel heating system (oil, gas, or liquefied petroleum gas (LPG)).

Through the Boiler Upgrade Scheme, you could get a grant to cover part of the cost of replacing fossil fuel heating systems with a heat pump or biomass boiler. Fossil fuel heating systems include oil, gas, electric or LPG (liquefied petroleum gas).

Common challenges and how to avoid them

Heat pump sizing errors

When it comes to heat pumps, incorrect sizing can result in high bills or insufficient heating. It is important to hire MCS-certified installers who will carry out detailed assessments and calculations to ensure the heat pump will be able to heat your home effectively.

When choosing a heat pump, size really matters, but the size of a heat pump doesn’t mean its physical dimensions. Heat pump size refers to its heating capacity, typically measured in kilowatts (kW).

Choosing the right size is crucial: a pump that’s too small won’t heat your home efficiently, and one that’s too large will cycle on and off too often, wasting energy and shortening its lifespan.

Heat pump sizing depends on several factors:

• Property size and layout
• Insulation levels
• Window size and orientation
• Local climate
• Heating system (e.g., underfloor heating or radiators)

As a rough guide:

• A small, well-insulated home may only need a 4–6 kW heat pump.
• A medium-sized home (3–4 bedrooms) might need a 7–10 kW unit.
• Larger or poorly insulated properties may require 12–16 kW or more.

To get the most accurate sizing, a professional should perform a room-by-room heat loss calculation. This assesses how much heat each space loses and ensures the pump can meet your heating and hot water demands efficiently.

Poor insulation or thermal loss

Air source heat pumps and underfloor heating deliver heat at a lower temperature, so homes with inadequate insulation won’t benefit fully from this system. Improving your home’s energy efficiency before installing a heat pump is crucial.

Incorrect flow temperature settings

If your heating system’s flow temperature setting is too high, you will be using lots of energy to keep it running which will be costly. If they are set too low, the system won’t meet heating demands. A professional setup with smart thermostats can help you to maintain balance.

Response time differences

UFH takes longer to heat up and cool down than radiators, so pre-programming your heating schedule and using zoning controls can help manage this effectively.

Real-world performance and efficiency

SCOP and seasonal performance

A well-installed air source heat pump typically achieves a SCOP of 3.0 to 4.5, meaning for every unit of electricity, you get 3 to 4.5 units of heat. This is highly efficient, especially compared to electric heaters.

How they perform in cold weather

Because ASHPs extract heat from the air, there is a common misconception that they would not be effective in the UK due to our mild, often cold, climate. In reality modern ASHPs work effectively even at sub-zero temperatures. Some are designed specifically for colder climates, maintaining good efficiency down to -15°C or lower.

Tips for maximising efficiency

To maximize air source heat pump (ASHP) efficiency, there are several steps you can take.

• Use a low flow temperature (35–45°C), ideally with underfloor heating or oversized radiators.
• Enable weather compensation and avoid frequent cycling by running the system continuously at low power.
• Insulate your home well, seal drafts, and upgrade to double/triple glazing.
• Maintain the system regularly and monitor performance (COP).
• Avoid using electric immersion heaters unless necessary.
• Smart thermostats and solar PV integration can further boost efficiency.
• Set consistent temperatures rather than constantly turning the system on/off.
• Ensure the external unit is unobstructed and clean.

These steps reduce energy use, lower costs, and improve comfort year-round.

By combining air source heat pumps and underfloor heating, homeowners can enjoy lower energy bills, improved comfort, and a reduced environmental footprint. If you’re considering the switch, be sure to consult with a qualified installer to determine the best setup for your home.

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