A heat pump does not need underfloor heating. Energy Saving Trust describes an air source heat pump as heating rooms via radiators or underfloor heating, so radiators alone are one of the two emitter options it names. Whether a floor is allowed in your rooms is a separate question, and MCS's tables answer it. The deciding number is the room's specific heat loss in watts per square metre. Below 30 W/m² a screed floor under tiles will run at a 35°C flow temperature with pipes up to 300mm apart. Above 100 W/m² MCS's table stops offering an underfloor design at any flow temperature and tells the designer to reduce the heat loss instead. Every figure here comes from the current MCS heat pump design standard, MCS's reference tables, gov.uk, Home Energy Scotland or Energy Saving Trust, read on 19 October 2026.
Why underfloor heating keeps coming up
The case for a floor rather than radiators is the flow temperature it lets the heat pump run at. Energy Saving Trust puts it plainly in its underfloor heating guide: with underfloor heating the flow temperature could be lower than with radiators, and that should result in the heat pump running much more efficiently.
MIS 3005-D makes the same point enforceable rather than rhetorical: the installer must give you the installation's seasonal efficiency figure at your design flow temperature, taken from the MCS website, not a headline number. We have gone through what that looks like per model on the Ecodan page, and it is the same arithmetic behind the radiator question.
None of that makes the job cheaper. Energy Saving Trust puts a typical air source heat pump installation at around £12,000 before any grant, and EST prices wet underfloor heating separately, per square metre of floor, as set out further down.
The MCS table: pipe spacing, not radiator size
For radiators MCS publishes an oversize factor you multiply the room's heat loss by. For underfloor heating it publishes a maximum pipe spacing instead, and in a lot of cells it publishes nothing at all. The source is MGD 007, the MCS heat pump reference document. Its own key explains the notation: "PS≤150 means UFH pipes should be spaced at 150mm or less to achieve the design condition", and a cell reading REDUCE HEAT LOSS means the system cannot perform at the design parameters stated.
At a design flow temperature of up to 35°C, the most efficient row in the table, this is what MCS allows across the six room heat loss bands and both underfloor constructions.
| Room specific heat loss | Screed, tile | Screed, wood | Screed, carpet | Aluminium panel, tile | Aluminium panel, wood | Aluminium panel, carpet |
|---|---|---|---|---|---|---|
| Less than 30 W/m² | PS≤300 | PS≤300 | PS≤200 | PS≤200 | PS≤200 | PS≤150 |
| 30 to 50 W/m² | PS≤300 | PS≤100 | Reduce heat loss | PS≤100 | Reduce heat loss | Reduce heat loss |
| 50 to 80 W/m² | PS≤100 | Reduce heat loss | Reduce heat loss | Reduce heat loss | Reduce heat loss | Reduce heat loss |
| 80 to 100 W/m² | Reduce heat loss | Reduce heat loss | Reduce heat loss | Reduce heat loss | Reduce heat loss | Reduce heat loss |
| 100 to 120 W/m² | Reduce heat loss | Reduce heat loss | Reduce heat loss | Reduce heat loss | Reduce heat loss | Reduce heat loss |
| 120 to 150 W/m² | Reduce heat loss | Reduce heat loss | Reduce heat loss | Reduce heat loss | Reduce heat loss | Reduce heat loss |
Source: MCS MGD 007, heat emitter guidance table, design flow temperature up to 35°C after any blending valve.
Read down the first column and the shape is clear. A 35°C design survives to 50 W/m² only under tile on screed, and in the 30 to 50 W/m² band the covering decides it: a tiled screed floor sits at 300mm spacing while the same floor under carpet is a reduce-heat-loss cell.
The 41 to 45°C row of the same table allows considerably more.
| Room specific heat loss | Screed, tile | Screed, wood | Screed, carpet | Aluminium panel, tile | Aluminium panel, wood | Aluminium panel, carpet |
|---|---|---|---|---|---|---|
| Less than 30 W/m² | PS≤300 | PS≤300 | PS≤300 | PS≤300 | PS≤300 | PS≤300 |
| 30 to 50 W/m² | PS≤300 | PS≤300 | PS≤300 | PS≤200 | PS≤200 | PS≤150 |
| 50 to 80 W/m² | PS≤300 | PS≤100 | PS≤100 | PS≤150 | Reduce heat loss | Reduce heat loss |
| 80 to 100 W/m² | PS≤200 | Reduce heat loss | Reduce heat loss | PS≤100 | Reduce heat loss | Reduce heat loss |
| 100 to 120 W/m² | Reduce heat loss | Reduce heat loss | Reduce heat loss | Reduce heat loss | Reduce heat loss | Reduce heat loss |
| 120 to 150 W/m² | Reduce heat loss | Reduce heat loss | Reduce heat loss | Reduce heat loss | Reduce heat loss | Reduce heat loss |
Source: MCS MGD 007, same table, design flow temperature 41 to 45°C.
In the two worst bands, 100 W/m² and above, MGD 007 prints no pipe spacing at all: one reduce-heat-loss cell covers each underfloor group whole, every flow temperature row from 35°C to 65°C, screed and aluminium panel alike. The guidance key spells out what that means, which is that the system cannot perform at the design parameters stated. In a cold house the insulation comes first and the emitter comes second.
The flow temperature column is read after any blending valve, and MGD 007's own heading says to add 5°C to the heat pump flow temperature where a blending valve is fitted. So a floor designed to run at 45°C with a blending valve in the circuit means the heat pump itself is putting out about 50°C, and the heat pump's temperature is the one that sets the efficiency.
Ask for your rooms in watts per square metre
You cannot read either table above without knowing your own rooms' specific heat loss, and the MCS design standard already entitles you to it. Clause 5.9.2 of MIS 3005-D says that prior to the installation commencing the customer shall be provided in writing with, among other things, "all specific room heat losses (in W/m2)", and the standard's own note defines specific heat loss as the total heat loss divided by floor area.
The same clause requires the type and dimensions of the emitters, the design emitter temperature based on the worst performing room, the design flow temperature of the water leaving the heat pump before any blending valves, and the installation's seasonal efficiency figure at that design flow temperature, taken from the MCS website.
Clause 5.9.2 makes that figure yours to ask for before work starts, not a courtesy. With it in hand you can look your own kitchen up in the tables above.
The floor covering matters as much as the pipework
In MGD 007's tables the covering changes the pipe spacing, and in places decides whether a design is offered at all. In the 50 to 80 W/m² band at a 41 to 45°C design, a screed floor under tiles runs at 300mm pipe spacing while the same floor under wood or carpet drops to 100mm, which is three times as much pipe in the same room.
Energy Saving Trust's guidance lines up with that. Stone and ceramic tiles transfer heat efficiently and are a good option. Engineered wood copes with the temperature swings. Vinyl and laminate may be suitable as long as they are not so thick that they stop the heat coming through. Carpet is allowed, though EST says it can make a room take longer to heat, and it points at a tog rating of 2.5 or lower for the carpet including its underlay, a figure it takes from Home Building and Renovating.
The covering is also the one input you can revisit after the floor is down, which the pipe spacing inside a screed is not.
Screed or aluminium panel
MGD 007 treats screed and aluminium panel as two separate underfloor constructions, each with its own tile, wood and carpet columns. Compare the two halves of either table above, cell by cell, and the screed columns allow a wider pipe spacing or a design where the aluminium panel columns do not.
At 35°C in a room under 30 W/m², screed under tiles runs at 300mm spacing and the aluminium panel version of the same room is down to 200mm. In the 30 to 50 W/m² band at the same temperature, screed under tiles is still allowed at 300mm while aluminium panel under wood or carpet is already a reduce-heat-loss cell.
That is a reason to check which of the two constructions your quote assumes, not a reason to rule aluminium panel out. A 41 to 45°C design on aluminium panel is a go-ahead cell in MGD 007 up to 80 W/m² under tile. It simply will not behave like screed in the table.
What it costs, and what the grants pay for
Energy Saving Trust quotes wet underfloor heating at £85 to £110 per square metre installed, and electric at £50 to £85, figures it takes from Checkatrade's cost guide. Those are per square metre of floor, before the heat pump itself. EST adds that you can save costs if you are already renovating, particularly if you are already replacing the floor.
What the three UK schemes publish is money towards the heat pump. None of them lists underfloor heating as a funded measure:
- England and Wales. The Boiler Upgrade Scheme, which gov.uk says is open to people in England and Wales, gives £7,500 towards an air source heat pump and £7,500 towards a ground source heat pump, one grant per property, with an additional £1,500 until March 2027 if your property is heated by oil or LPG and has no mains gas connection. The grants gov.uk lists are for heat pumps and biomass boilers, so radiator or underfloor work sits inside your installer's quote.
- Scotland. The Home Energy Scotland Grant and Loan offers up to £7,500 of grant funding for a heat pump plus an optional £7,500 interest-free loan, with a £1,500 uplift for rural and island homes. Only heat pumps providing 100% of heating and hot water qualify, and replacement heat pumps are loan-only. Its funding table covers underfloor insulation, at £1,500 grant and £500 loan, not underfloor heating.
- Northern Ireland. No equivalent heat pump grant, as Energy Saving Trust states on its air source heat pump page.
Set against the £12,000 EST gives as a typical air source installation, that is where most of the budget argument sits. Full numbers are in our guide to what a heat pump costs in the UK, and the running-cost side of it in heat pump versus gas boiler.
Underfloor downstairs, radiators upstairs
Energy Saving Trust says installers sometimes suggest underfloor heating for the ground floor with radiators upstairs, because it can be less expensive to install and involve less disruption. It works, with one condition that gets skipped.
MIS 3005-D clause 5.9.2 requires the design emitter temperature to be stated for the worst performing room, which is the clause that matters here. EST reaches the same place by a different route: get the upstairs radiator sizes right, which is likely to mean larger radiators with more panels, so that enough heat is emitted upstairs while keeping a suitable flow temperature for downstairs.
A mixed system does not let you skip the upstairs radiator sizing, then. It makes that sizing the thing deciding your bills.
Electric underfloor heating is a different product
Nothing on this page applies to electric underfloor heating. Energy Saving Trust describes dry systems as electric mats or cables that generate heat when electricity is fed through them, effective for quickly warming small areas such as a bathroom floor, but costly to run over longer periods or in larger spaces, like any direct-acting electric heater.
A heat pump, by contrast, sends warm water to the emitters. If a quote mentions electric underfloor heating in the same breath as a heat pump, it is describing a comfort extra in one room rather than the heating system.
What to ask for before you sign
- The specific heat loss of every room in W/m², which MIS 3005-D 5.9.2 already requires in writing before work starts. Without it, no one can read the MCS table for your house.
- The design flow temperature leaving the heat pump, before any blending valve, and the worst performing room that set it.
- The pipe spacing and the floor construction proposed for each underfloor room, so you can check both against MGD 007.
- The floor covering the design assumes. A design validated for tile and then carpeted is a different system.
- The seasonal efficiency at that design flow temperature, taken from the MCS website, not the headline figure from the brochure.
MIS 3005-D adds one more protection worth knowing. Clause 5.5.5 says that where a design proposes a flow temperature greater than 55°C, an alternative design at 55°C or lower should also be provided, and the differences in efficiency and energy consumption must be explained to you so you can choose. Clause 5.5.4 says high temperature heat pumps should be avoided unless the application genuinely requires above 55°C.
Get a survey-based price for your own floor
Underfloor heating only answers itself after a room-by-room heat loss calculation. Tell us about your home once and we will pass your details to MCS-certified heat pump installers covering your postcode.
Frequently asked questions
No. A heat pump works with radiators, underfloor heating or a mix of the two, and MCS's MGD 007 reference tables publish designs for all of them. Underfloor heating is attractive because it emits the same heat at a lower flow temperature, which is where a heat pump is most efficient, but it is an efficiency choice rather than a requirement. In a room losing 100 W/m² or more, MCS's table does not offer an underfloor design at any flow temperature and says to reduce the heat loss instead, and the key defines that condition as the system being unable to perform at the design parameters stated.
It depends on how much heat the room loses. MCS's MGD 007 table allows a 35°C design in every underfloor cell for a room losing under 30 W/m². In the 30 to 50 W/m² band it allows only screed under tile at 300mm, screed under wood at 100mm and aluminium panel under tile at 100mm, and screed under carpet is already a reduce-heat-loss cell. From 50 to 80 W/m² the only 35°C option left is screed under tile at 100mm. At 41 to 45°C the table opens up to rooms losing up to 100 W/m² with a tiled screed floor. The temperature column is read after any blending valve, and MGD 007 says to add 5°C to the heat pump flow temperature where a blending valve is fitted.
Yes, but it costs you either pipe spacing or flow temperature. In MCS's table a screed floor in a room losing 50 to 80 W/m² runs at 300mm pipe spacing under tile at a 41 to 45°C design, and at 100mm under carpet, which is three times the pipework for the same room. Energy Saving Trust advises checking the tog rating of the carpet including its underlay and points at 2.5 or lower, a figure it takes from Home Building and Renovating. Tile and stone transfer heat best, engineered wood copes well, and vinyl or laminate works if it is not too thick.
Energy Saving Trust quotes £85 to £110 per square metre for a wet system and £50 to £85 for an electric one, figures it takes from Checkatrade's cost guide. Those are per square metre of floor, on top of the heat pump itself, which EST puts at around £12,000 typically. Costs fall if the floor is already coming up as part of a renovation. No UK grant pays for the underfloor heating: the Boiler Upgrade Scheme's £7,500 in England and Wales and Home Energy Scotland's £7,500 grant both go towards the heat pump.
Energy Saving Trust says installers sometimes suggest it because it can be less expensive to install and involve less disruption. The catch is the design temperature. MIS 3005-D clause 5.9.2 requires the installer to state the design emitter temperature based on the worst performing room, in writing, before work begins, and EST advises sizing the upstairs radiators larger, with more panels, to keep the flow temperature down.
MCS's MGD 007 treats them as two separate underfloor constructions, each with its own tile, wood and carpet columns. In a room losing under 30 W/m² at a 35°C design, screed under tile is allowed at 300mm pipe spacing while the aluminium panel version of the same room drops to 200mm. Both appear as go-ahead cells in the table at the right heat loss and flow temperature.
No. A heat pump sends warm water to its emitters, and Energy Saving Trust describes electric underfloor heating as mats or cables that generate heat when electricity is fed through them, so it is a separate product rather than part of the heat pump's emitter circuit. Energy Saving Trust describes electric systems as effective for warming small areas such as a bathroom, but costly to run over longer periods or in larger spaces, like any direct-acting electric heater. If a quote mentions it alongside a heat pump, it is a comfort extra in one room rather than part of the heating system.