There is no single best answer. For whole-house low-temperature heating in a new build or extension, wet underfloor heating usually gives the best efficiency; for a quick upgrade with minimal disruption, modern radiators are usually the smarter choice. The deciding factors are your renovation stage, your heat source and how well insulated your rooms already are. If you are unsure, start with a heat-loss calculation or an installer quote before committing either way.
TL;DR:
- Electric underfloor heating costs about £50 to £85 per square metre to install, while wet systems cost £85 to £110 and suit whole floor projects.
- Heat pumps work most efficiently at 35 to 55°C; well sized radiators can match underfloor heating in insulated homes, but poor insulation limits both.
- Wet underfloor heating is best installed while floors are being built or renewed; retrofitting usually means lifting flooring, raising floor height, and redecorating.
- Get a room by room heat loss calculation and flow temperature targets before accepting quotes; compare two to three installers on design, not price alone.
- Schedule underfloor heating an hour or two before use because floors respond slowly; carpets and underlay above roughly 1.5 tog can reduce output.
Table of Contents
- 1. What underfloor heating is: wet and dry systems explained
- 2. What radiators are and how sizing works for low temperatures
- 3. Efficiency and running costs: flow temperatures and heat-pump compatibility
- 4. Installation and retrofit: disruption, timing and hybrid layouts
- 5. Controls and zoning: thermostats, TRVs and smart systems
- 6. Maintenance, reliability and common problems
- 7. Comfort, flooring and space: design implications of your choice
- 8. Preparing for a low-temperature heating system
- 9. Decision checklist: what to do next
- When an extension is the right moment to choose underfloor heating
- FAQ
- Sources
1. What underfloor heating is: wet and dry systems explained
Underfloor heating works by turning the whole floor into a radiant heat emitter rather than relying on a single hot object in the room. There are two main types, and they behave quite differently once installed.
Wet (hydronic) systems circulate warm water through pipework laid beneath the floor, usually embedded in screed, and are fed by a boiler or heat pump, as explained by Sydney Underfloor Heating. Dry (electric) systems use heating mats or cables, typically installed under tiles, and run from the mains electricity supply.
- Dry electric systems cost roughly £50 to £85 per square metre to install, making them a practical choice for bathrooms and small retrofit jobs.
- Wet systems cost roughly £85 to £110 per square metre, reflecting the extra labour of laying pipework and screed, but they suit whole-floor installations in new builds and extensions.
- Electric systems tend to cost more to run over time because they rely on electricity as the direct heat source.
- Wet systems pair well with heat pumps and allow lower flow temperatures, which keeps running costs down over the long term.
2. What radiators are and how sizing works for low temperatures
Radiators remain the default heat emitter in most UK homes, and the category has moved well beyond the single flat panel. Single-panel, double-panel and triple-panel radiators each offer different heat outputs for the same wall space, and fan-assisted radiators add a small fan to push warm air into the room faster, which suits spaces with limited wall length.
The sizing question matters more than most homeowners realise. Radiators sized for a boiler running at 55 to 70°C often fall short when the system is switched to a heat pump running at lower flow temperatures, so they usually need upsizing to maintain the same heat output.
- Single, double and triple-panel radiators scale heat output roughly with the number of panels, letting you match capacity to room size without changing footprint dramatically.
- Fan-assisted radiators boost output from a compact unit, useful where wall space is tight.
- Replacing an existing radiator with a larger double-panel unit for heat-pump readiness costs around £200 on average.
- Radiators suit staged, room-by-room upgrades where you want to avoid disturbing floors or finished décor.
3. Efficiency and running costs: flow temperatures and heat-pump compatibility
Flow temperature is the figure that decides how efficiently any heating system runs, and it is where underfloor heating and radiators genuinely diverge. Heat pumps operate most efficiently at flow temperatures of around 35 to 55°C, well below the 55 to 70°C that conventional boilers commonly use.
Underfloor heating can reduce heat-pump energy use because it spreads heat over a large surface area, allowing the system to run at lower flow temperatures than radiators typically need. This is one reason the Energy Saving Trust and RICS both flag UFH as a natural fit for heat-pump retrofits.
That said, the building itself sets the ceiling on performance:
- Insulation quality and the coldest room in the house, the so-called 'worst room', limit how low the flow temperature can go without leaving that room cold.
- A well-insulated home can run UFH or correctly sized radiators at similarly efficient flow temperatures.
- Properly upsized radiators can match UFH performance in many rooms once the fabric of the building supports lower temperatures.
Choosing the emitter matters less than fixing draughts and insulation first, because neither system outperforms the other in a poorly insulated room.
4. Installation and retrofit: disruption, timing and hybrid layouts
Wet underfloor heating involves laying insulation, pipework and screed, so it is disruptive and expensive to retrofit into a finished room with existing flooring. Dry electric systems and radiator swaps are far less invasive, since they can often be fitted without major structural work.
- New floors going in during a new build, extension or major renovation are the natural moment to install wet UFH, since the groundwork is already being disturbed.
- Retrofitting wet UFH into a finished room usually means lifting floors, raising floor height and redecorating, which pushes costs and timescales up sharply.
- A common compromise is UFH on the ground floor, installed during new floor construction, with radiators kept or upgraded upstairs where disruption would be harder to justify.
- Hybrid layouts need careful sizing on both sides: UFH loops sized for the ground floor's heat loss and radiators upsized to work at the same flow temperature as the UFH circuit.
Expect a wet UFH installation in a single room to take several days including screed curing time, while a radiator swap is typically a one-day job.
5. Controls and zoning: thermostats, TRVs and smart systems
Radiators use thermostatic radiator valves (TRVs) on each unit, giving quick, room-by-room control. Underfloor heating uses a manifold with zone valves, controlling larger areas or whole floors, and because the floor itself holds heat, UFH responds more slowly to changes in setting.
- TRVs let you adjust individual rooms in minutes; UFH zones typically take longer to heat up and cool down.
- Scheduling UFH ahead of when you need the room warm helps offset its slower response.
- Smart thermostats can pre-empt UFH's lag by learning your routine and adjusting start times automatically.
- In hybrid homes, each room or zone needs independent temperature control so the slower UFH zones do not force radiators to overheat elsewhere.
Pro Tip: Set UFH zones on a timer that starts an hour or two before you need the room warm, rather than relying on instant thermostat changes.
6. Maintenance, reliability and common problems
Radiators need occasional bleeding to clear trapped air and valve replacement every few years as parts wear. Underfloor heating needs less routine attention, but manifold checks and leak detection matter if performance drops.
- Bleed radiators when they feel cooler at the top than the bottom, a sign of trapped air.
- Check UFH manifolds periodically for pressure loss, which can signal a slow leak in the pipework.
- Thick carpet, underlay or hardwood flooring can insulate UFH too well, forcing higher flow temperatures to compensate.
- Call a specialist if you notice pressure loss, uneven heat across rooms, or heating that takes unusually long to respond.
7. Comfort, flooring and space: design implications of your choice
Underfloor heating warms the floor itself, giving an even, ambient warmth that many people find more comfortable than the localised convective heat from a radiator. It also frees up wall space, since there is no unit to work around when placing furniture.
- Heavy floor coverings reduce UFH output: guidance points to tiles at roughly 0.0 tog, hardwood at around 1.0 tog and carpet with underlay at around 1.5 tog, with a practical maximum around 1.5 tog before performance suffers.
- Avoid placing fitted wardrobes, kitchen units or heavy furniture with no legs directly over UFH pipework, since trapped heat can damage both the flooring and the unit.
- Removing radiators from walls opens up design options that would otherwise be blocked by pipework and brackets.
8. Preparing for a low-temperature heating system
Before choosing an emitter, commission a room-by-room heat-loss calculation. MCS guidance notes that a system's performance is set by its worst-performing room, so every room needs checking, not just the ones being renovated.
- Prioritise insulation, draught-proofing and window upgrades before changing emitters, since reducing heat loss helps any system run more efficiently.
- Size emitters, whether UFH loops or radiators, against the flow temperature you plan to run, particularly if a heat pump is on the horizon.
- Ask installers for their heat-loss calculations, pipe spacing plans and flow-temperature targets in writing before work starts.
Pro Tip: Ask any installer for their MCS accreditation and a written heat-loss calculation; a credible quote should never skip this step.
9. Decision checklist: what to do next
Work through a few quick questions before you commit to either system.
- What stage is your renovation at: new floors going in, or a finished room you want to avoid disturbing?
- Are you planning to move to a heat pump, and if so, when?
- How much disruption can you realistically tolerate this year?
- What is your budget range for this specific room or project?
- Get a heat-loss calculation before comparing quotes, so every installer is pricing against the same numbers.
- Collect two to three installer quotes and compare them on design detail, not just headline price.
- Check for MCS certification, ask for references, and confirm the warranty terms in writing before signing anything.
When an extension is the right moment to choose underfloor heating
An extension or major floor renewal is often the easiest time to fit wet underfloor heating, since the groundwork and new flooring are already part of the build. We manage extension design and build projects under one coordinated team, which keeps planning, building regulations and construction aligned from the first conversation. If you are weighing up extension options that could make room for underfloor heating, we are happy to talk through what fits your project.
— Raja
FAQ
What are the downsides of underfloor heating?
Wet underfloor heating is disruptive and costly to retrofit into a finished room, since it usually requires lifting floors and laying new screed. It also responds more slowly to temperature changes than radiators, so it suits scheduled heating rather than quick adjustments.
Which is cheaper to run, underfloor heating or radiators?
Wet underfloor heating paired with a heat pump tends to run efficiently because it works well at lower flow temperatures, while electric underfloor heating tends to cost more to run long-term since it draws directly on electricity. Properly sized radiators can match UFH running costs in a well-insulated home.
What are common problems with underfloor heating?
Common issues include pressure loss in the pipework, uneven heating caused by incorrect pipe spacing, and reduced output when floor coverings are too insulating. Floor coverings above a practical maximum around 1.5 tog can force the system to run at higher, less efficient flow temperatures.
What furniture can you not put on underfloor heating?
Avoid placing fitted units, heavy furniture without legs, or anything that traps heat directly over underfloor heating pipework, since the trapped warmth can damage both the flooring and the heating elements. Furniture with legs that allow some airflow underneath is generally fine.