What temperature should underfloor heating be set at? Room, floor and flow temperatures

People ask "what temperature should underfloor heating be?" and mean three different things: the number on the thermostat, how warm the floor feels, and how hot the water in the pipes is. They are linked, but you set them in different places and they have different limits. Mixing them up is the most common reason a floor feels too cool, a wood floor gaps, or a heat pump runs less efficiently than it should.

This guide takes each temperature in turn: the room setting, the floor surface limit for each floor covering, the flow temperature from a boiler or a heat pump, and whether to turn the heating down at night. Every figure is from a published standard or a manufacturer's document, listed at the end.

What should I set the underfloor heating thermostat to?

Set it to the room air temperature you find comfortable, the same as you would with radiators. In most homes that is 20 to 21°C in living areas. BS EN 1264 designs living rooms for a 20°C room and bathrooms for 24°C.

Room	Typical setting	Notes
Living room, kitchen, dining	20 to 21°C	Standard design room temperature is 20°C
Bedroom	18 to 20°C	Public health advice is to keep rooms at 18°C or more
Bathroom	Up to 24°C	EN 1264 designs bathrooms for 24°C
Away or unused	Frost setting	Heatmiser neoStat default is 12°C, adjustable 7 to 17°C

Because underfloor heating warms the room from a large, low-temperature surface, many people find they are comfortable at the same or a slightly lower air temperature than with radiators. Find your level by starting a little low and raising the setting 1°C at a time, leaving a full day between changes so the floor can catch up.

Do not turn the thermostat right up to warm a room faster. The floor gives out heat at a rate set by its surface temperature, so a higher setting only makes the room overshoot later.

What temperature should the floor surface be?

No more than 29°C in the main part of a room. BS EN 1264 sets that limit for occupied areas, allows up to 35°C in an edge band no more than 1m wide along cold outside walls, and allows room temperature plus 9°C in bathrooms, which is 33°C in a 24°C bathroom.

The comfort standard ISO 7730 gives 19 to 29°C as the acceptable floor range for people in light shoes. So a floor that feels pleasantly warm rather than hot is working as designed. At the 29°C limit, a floor in a 20°C room gives about 100W/m², and the edge band up to about 175W/m².

Floor finish	Maximum surface temperature	Source of the limit
Tile, stone, porcelain	29°C (33°C in bathrooms)	BS EN 1264 limit
Solid or engineered wood	27°C	Wood flooring maker's limit
Laminate, LVT, vinyl, carpet	Check the product	Each maker sets its own figure
Edge band by glazing	35°C	BS EN 1264, up to 1m wide

Wood flooring makers limit the board surface to 27°C, because more heat can dry and move the boards. One maker notes that the flow temperature needed to hold a 27°C surface will normally be between 35 and 45°C, and asks for room humidity of 35 to 65% in homes. For more detail on each finish, see our guide to underfloor heating under tiles, LVT, laminate, wood and carpet.

How do I stop the floor getting too hot?

Use a thermostat with a floor probe and set a floor limit. The thermostat then controls the room air temperature but switches off if the floor reaches the limit you set.

• Air sensing: the thermostat reads the room air only. Fine for tiled floors on a water system with a mixing valve.
• Floor sensing: the thermostat reads a probe in the floor. Useful in bathrooms, where you want a warm floor rather than a set air temperature.
• Air with floor limit: the thermostat controls the air but caps the floor. The best choice under wood, laminate and LVT.

On the Heatmiser neoStat, the floor limit can be set from 20 to 45°C and is 28°C out of the box. Under wood, lower it to 27°C or the flooring maker's figure. A 10K floor probe sits between two pipe runs or heating cables, not on top of one.

Electric underfloor heating should always have a floor probe, because the heating cable is right under the finish. The Heatmiser neoStat-e has the same 20 to 45°C floor limit range and switches loads up to 16A. Its final connection must be made by a qualified electrician under Part P and BS 7671.

What flow temperature does water underfloor heating need?

Usually between 30 and 45°C, much lower than radiators. The exact figure depends on the room's heat loss, the pipe spacing, the screed and the floor covering.

Situation	Typical flow temperature
Well-designed screed floor, heat pump	30 to 40°C
General UFH design range	30 to 45°C
Under wood, to hold a 27°C surface	35 to 45°C
Maximum, cement or calcium sulphate screed	55°C
Maximum, gypsum-based floors	50°C

Pipe spacing has a big effect. One published simulation study found the flow temperature needed for the same room rose from 36.6°C at 100mm pipe spacing to 47.5°C at 400mm. Closer pipe lets you run cooler water for the same heat. Our guide to pipe centres covers the trade-offs.

Return water normally comes back 5°C cooler than the flow. That 5K difference is the standard design figure used in BS EN 1264 based sizing.

What should the boiler flow temperature be with underfloor heating?

The boiler can stay at the temperature its radiators and hot water need, because a mixing (blending) valve at the manifold cuts the water down to the floor's temperature. BEAMA's controls guidance also asks for a high-limit thermostat after the mixing valve, so the floor can never get boiler-hot water.

• Combi boiler: a 65°C setting is a sensible starting point for radiators, then lower towards 60°C or below if the house stays warm.
• System or regular boiler with a cylinder: do not go below 65°C without advice from a heating engineer, because of the Legionella risk in stored hot water.
• UFH loop: set by the blending valve, typically to the 30 to 45°C range above.

A condensing boiler starts to condense more, and so runs more efficiently, once the water returning to it is below about 54°C. Underfloor heating return water is far cooler than that. A blending valve pump pack with a 20 to 55°C range covers every floor type. Any work on the boiler itself, such as connecting a UFH circuit, is a job for a Gas Safe engineer. See underfloor heating with a combi or system boiler for how the connection works.

What flow temperature should a heat pump run for underfloor heating?

As low as will keep the house warm, typically 30 to 40°C, set by weather compensation rather than a fixed figure. The heat pump raises the flow temperature as the outside temperature falls and lowers it as the weather warms.

The Energy Saving Trust's installer guidance works through an example designed for 45°C flow at -5°C outside, with the curve dropping to 20°C flow at 20°C outside. Most houses respond well to a minimum flow of 20 to 25°C. Every degree matters: one heat pump maker says each 1°C above the ideal flow temperature adds about 2 to 2.5% to electricity use.

With a heat pump you often do not need a mixing valve, because the water is already at floor temperature, but BEAMA advises checking this for each heat pump. Our guide to underfloor heating with a heat pump covers design flow temperatures in detail.

Should I turn underfloor heating down at night or when I go out?

Turn it down a little, not off. On a screed floor, a setback of about 2°C is enough. Bigger drops take a lot of energy to recover in a short time, which can cancel the saving, and a setback set late in the evening may not be felt until the next morning.

• Screed floors: BEAMA recommends automatic setback when unoccupied for screeds thicker than 65mm, rather than switching off.
• Overlay boards and electric mats: these warm faster, so timed heating that follows your day works well.
• Heat pumps: steady, slowly changing temperatures suit them best. Avoid big swings.

If your thermostat has optimum start, turn it on. The neoStat can start heating up to 5 hours early so the room reaches temperature on time. For more on response times, read how long underfloor heating takes to warm up.

Frequently asked questions

What is a good temperature for underfloor heating?

About 20 to 21°C room temperature in living areas, with the floor surface no higher than 29°C, or 27°C under wood. Bathrooms are often set warmer, up to 24°C.

Why does my floor not feel hot?

It is not meant to. BS EN 1264 caps the surface at 29°C in living areas and ISO 7730 puts the comfortable range at 19 to 29°C, so a working floor feels gently warm rather than hot.

Is 30°C too hot for underfloor heating?

As a floor surface temperature, yes for most rooms: BS EN 1264 caps occupied areas at 29°C. As a water flow temperature, 30°C is low and typical for a heat pump system.

What is the maximum water temperature for underfloor heating?

55°C for sand and cement or calcium sulphate screeds and 50°C for gypsum-based floors. A high-limit thermostat after the mixing valve protects the floor on a boiler system.

Should I leave underfloor heating on all the time?

On a screed floor, keeping it on with a small night setback of about 2°C usually works better than switching off. Low-mass overlay and electric systems can be run on a timer.

What should I set the floor limit to under wood?

27°C, or lower if your flooring maker says so. Set it on the thermostat's floor limit and fit the floor probe between pipe runs.

Do I need to change my boiler settings for underfloor heating?

Usually not. The blending valve at the manifold reduces the temperature for the floor, so the boiler stays set for radiators and hot water.

Sources: Wu et al. 2021, comfortable floor temperatures (ISO 7730 ranges), Energy Saving Trust weather compensation guidance, Göbel et al. 2021, underfloor heating system model, BEAMA guidance on controls for water UFH, Nesta boiler optimisation report, Which? boiler flow temperature advice, Heatmiser neoStat datasheet, Cambridgeshire County Council cold weather advice (18°C)