You do not automatically need underfloor heating for an air source heat pump. In many UK homes, correctly sized radiators are enough. The right choice depends on your property, insulation, and system design. Across Surrey and West Sussex, including Horley, Reigate, Redhill and Crawley, most heat pump installations use a mix of upgraded radiators and, in some cases, underfloor heating where it makes sense.
In this guide, we will explain how heat pumps affect your heating system and whether you need underfloor heating, larger radiators, or a combination of both.
We will cover:
- Why heat pumps change your heating system
- What underfloor heating is and how it works
- What upgrading radiators actually involves
- Why heat emitters matter for heat pumps
- Which option suits different types of homes
- Cost, disruption and installation differences
- Performance and comfort differences
- Can you combine both systems?
- Common mistakes and how to avoid them
- When a professional design is essential
Why do heat pumps change your heating system?
Heat pumps heat your home differently from gas or oil boilers. They run at lower temperatures to improve efficiency.
This efficiency is measured by the Coefficient of Performance, known as COP. COP simply means how much heat you get for each unit of electricity used.
Because heat pumps run cooler, your existing radiators may not give off enough heat unless they are sized correctly.
What this means for you is:
- You may need larger radiators
- Or underfloor heating
- Or a mix of both
This is a design question, not a simple yes or no.
What is underfloor heating and how does it work?
Underfloor heating uses pipes beneath your floor to gently warm the room from the ground up.
It works very well with heat pumps because it delivers heat efficiently at lower temperatures.
Key characteristics:
- Even heat across the whole room
- Warm floor surface
- Slower to heat up and cool down
It is designed to run steadily rather than switching on and off frequently.
Underfloor heating is not required for a heat pump, but it is often used in new builds or extensions.
What does upgrading radiators actually involve?
Upgrading radiators means increasing their heat output so they can work effectively at lower temperatures.
This may include:
- Replacing single panel radiators with double or triple panel versions
- Installing taller or wider radiators
- Adding extra radiators in larger rooms
You are not necessarily filling your home with oversized units. A proper design keeps them practical and proportional.
In many homes across Crawley and Reigate, upgrading radiators is the most straightforward way to make a heat pump work properly.
Why do heat emitters matter for heat pumps?
Heat emitters are the parts of your system that release heat into the room, such as radiators or underfloor heating.
With a heat pump:
- Lower flow temperatures mean less heat per radiator
- Larger surface area is needed to deliver the same warmth
- Poor sizing leads to cold rooms or higher running costs
If the system is not designed correctly, the heat pump may run at higher temperatures to compensate, which reduces efficiency and increases costs.
This is why correct sizing is critical.
Which option suits different types of homes?
The best option depends on your property and how much work you are planning.
Underfloor heating is often best for:
- New builds
- Major renovations
- Extensions where floors are being replaced
- Open-plan living areas
Larger radiators are often best for:
- Existing homes where floors are staying in place
- Retrofits with minimal disruption
- Budget-conscious upgrades
- Room-by-room improvements
For example, a full renovation in Horley might suit underfloor heating throughout, while a retrofit in Redhill or Crawley is more likely to rely on upgraded radiators.
JPEC Green Energy regularly assesses these scenarios and advises on what is realistic for each property.
What are the differences in cost and disruption?
Underfloor heating and radiator upgrades differ significantly in how they are installed.
Underfloor heating:
- Requires lifting floors
- May affect floor height and finishes
- Takes longer to install
- Higher upfront cost
Larger radiators:
- Installed using existing pipework where possible
- Minimal building work
- Faster installation
- Lower upfront cost
For most homes in Surrey and West Sussex, radiator upgrades are the simpler and more cost-effective option unless you are already doing major building work.
How do comfort and performance compare?
Both systems can heat your home effectively if designed properly, but they feel different.
Underfloor heating:
- Provides even heat across the space
- Feels comfortable underfoot
- Works best with steady operation
Radiators:
- Heat rooms more quickly
- Allow easier room-by-room control
- Respond faster to thermostat changes
The choice often comes down to lifestyle and expectations rather than just performance.
Can you combine underfloor heating and radiators?
Yes, and many homes do.
A common setup is:
- Underfloor heating downstairs
- Radiators upstairs
This works well because:
- Ground floors often benefit from open-plan layouts
- Upstairs rooms are easier to heat with radiators
- It balances comfort, cost and disruption
For example, a home in Reigate might use underfloor heating in a kitchen extension while keeping upgraded radiators in bedrooms.
A mixed system is often the most practical solution.
Common mistakes and how to avoid them
Some common problems include:
- Assuming underfloor heating is required for all heat pumps
- Keeping old radiators that are too small
- Undersizing new radiators to save money
- Ignoring insulation improvements
- Expecting fast heat-up from underfloor systems
These issues can lead to poor comfort and higher running costs.
A proper heat loss calculation, which measures how much heat each room needs, is essential.
Practical tips before you commit
Before deciding, think about:
- Whether you are renovating or keeping existing floors
- How much disruption you can tolerate
- Your budget
- How you use your home during the day
- Whether you prefer hidden heating or visible radiators
For example, a household in Crawley working from home may prioritise steady daytime heating, while a family out during the day may prefer faster response in the evenings.
JPEC Green Energy can assess your home and explain the best options clearly.
When is a professional design essential?
Always when installing a heat pump.
A proper design should include:
Room-by-room heat loss calculations
- Correct sizing of radiators or underfloor heating
- Flow temperature planning
- System balancing
This ensures your system runs efficiently and keeps your home comfortable.
JPEC Green Energy are experienced local installers who can survey, design, install and commission your system properly, while explaining the trade-offs in plain English.
So do you need underfloor heating or bigger radiators?
In most cases, you do not need underfloor heating to install a heat pump.
Larger radiators are often enough and are usually the most practical option in existing homes.
Underfloor heating is best suited to new builds, extensions or major renovations where floors are already being replaced.
The right solution depends on your property, your budget and how much disruption you are prepared to accept.
JPEC Green Energy can help
If you are considering an air source heat pump in Surrey or West Sussex, including Horley, Reigate, Redhill or Crawley, JPEC Green Energy can help you decide whether underfloor heating, larger radiators, or a mix of both is right for your property.
