Wet underfloor heating is the better choice when the floor is meant to heat the whole room, and electric underfloor heating is the better choice for a warm floor in one small room. Wet systems carry boiler-heated water through pipes in the floor; electric systems warm the floor build-up with mats or cables and leave your central heating untouched. Three things decide which fits: how much heat the room needs, how much height you have for the floor build-up, and whether the floor is coming up anyway. This page works through both options for a typical London home, with the rules that apply in England.
Wet or electric underfloor heating: which suits which room?
Wet underfloor heating is the usual answer where the floor is the main heat source for the room. A kitchen-diner, a garden room or an open-plan ground floor are typical cases. Electric underfloor heating is the usual answer where you want a warm floor rather than a new heat source. That points to a bathroom, an en-suite or a small utility.
Viessmann describes electric systems as strongest as supplementary heating, or in buildings with a low heat demand. They are simple to commission and give their heat up to the room quickly. Wet systems run at low water temperatures instead, and are designed for longer running times.
- Floor already coming up across a main living space: wet pipework, zoned from the boiler.
- One small room and a thin finished floor: electric mats with a low build-up.
- A mix in one house: wet circuits can be zoned, so some rooms run from the floor and others from radiators.
- Carpet or heavy rugs planned: expect poor heat transfer, whichever system goes in.
How does wet underfloor heating work with a gas boiler?
Wet underfloor heating circulates water heated by your boiler through pipes laid in the floor. The principle matches a radiator circuit, but the heated surface is far larger and the pipe spacing is tighter. Viessmann gives typical flow temperatures of 30–40 °C for underfloor heating, against around 70 °C for radiators. A sensor reads the temperature of the water coming back from the floor.
A combi boiler can run underfloor heating, sometimes with changes to the system. Viessmann warns that without a two-port valve the boiler can serve the floor and the radiators at once, overheat and go to fault. The valve separates the two circuits. If boiler type is still open, our guide on combi, system or regular boilers sets out the differences.
Worcester Bosch installation instructions require plastic underfloor pipe to be controlled by a thermostatic blending valve that limits the circuit to about 50 °C. They also call for barrier pipe, a copper or steel section at the appliance, and system parts rated to 3 bar. Those figures are model specific, so the manual for your own boiler decides. Sizing, zoning, balancing and the pressure test before the screed goes down are work for the installer.
Who can fit electric underfloor heating in a bathroom in England?
Electric underfloor heating in a room with a bath or shower is work for a registered electrician in England. Approved Document P (Electrical safety — Dwellings) treats a new circuit, and work in a room containing a bath or shower, as notifiable. Notifiable work is either notified to a building control body before it starts, or carried out by a member of an approved competent person scheme, who can self-certify. Electric mats normally need their own circuit, so both triggers often apply together.
Electric mats can be very thin, which is why they survive a retrofit that wet pipework would not. Viessmann lists its Vitoplanar mats at 1.3 mm, suitable for laying under laminate and parquet, with little installation work. A dry system also leaves your existing central heating alone.
FM Power fits wet underfloor heating as part of plumbing and heating work. Electric mats sit with an electrician, and we will tell you that rather than take the job on.
Which floor coverings suit underfloor heating, and which do not?
Underfloor heating works with stone, ceramic, linoleum, vinyl, laminate, wood and some carpets, according to Viessmann. Laminate has a clear limit: temperatures above 27 °C can damage the covering and should be avoided. Carpet and rugs are less suitable, because they transfer heat poorly. A thick rug over a heated floor holds back most of what the floor produces.
Build-up matters as much as the covering. Over wet pipes a screed layer is poured to give a flat surface for the finished floor. Insulation goes underneath, so heat travels up into the room instead of down into the ground. Ask what the finished floor level will be before doors, skirting or flooring are ordered.
What does retrofitting underfloor heating mean for an existing room?
Retrofitting underfloor heating means lifting the existing floor covering so pipes or cables can be laid. That is why the work is simpler in a new build, a renovation or an extension. A room you are already stripping back is the least disruptive moment to add it. Compared with swapping a radiator, the installation effort is higher.
Warm-up behaviour changes as well. Radiators bring a room up to temperature faster. Underfloor heating is designed for slower warm-up and longer running times, and gives an even surface without cold zones. Our underfloor heating page sets out what we install and how the circuits are tested.
The room decides, not the system name. A floor coming up across a main living space points to wet pipework off the boiler. One small room with a thin finished floor points to electric mats fitted by a registered electrician.
Which underfloor heating controls do the rules expect, and what can you set yourself?
Approved Document L, Volume 1: Dwellings, which applies in England, expects every underfloor heating system to have controls for setting its operating temperature. For electric underfloor heating, it expects the room thermostat to have a manual override. It also expects floors to be insulated against the ground or outside air, to limit heat loss. A 2026 edition has been published, so check the current edition and its transitional arrangements in the GOV.UK Approved Documents collection.
You can set the room thermostat and the time programme for the floor circuit yourself. Keep the set point inside the covering's limit — for laminate, above 27 °C risks damage. You can also check the boiler pressure gauge, use the reset button and bleed radiators. If some rooms never warm through, our guide on balancing radiators explains what comes next.
Manifold balancing, the blending valve setting, the pressure test and anything buried in the screed are the installer's work. Any change to the boiler, the gas pipework or the flue is work for a Gas Safe registered engineer. The Gas Safety (Installation and Use) Regulations 1998, as amended, require work on gas fittings to be carried out by a competent person.
If the same project raises questions about stored hot water at mains pressure, our page on Megaflo and unvented cylinders covers that side of the system.
Sources
- Viessmann — Underfloor heating vs. radiators: which should you choose?
- Viessmann — Is underfloor heating efficient?
- Viessmann — Can you have underfloor heating with a combi boiler?
- Viessmann — Electric underfloor heating (Vitoplanar)
- Worcester Bosch — Installation, commissioning and servicing manual
- GOV.UK — Conservation of fuel and power: Approved Document L
- GOV.UK — Approved Documents collection
- GOV.UK — Electrical safety: Approved Document P
- legislation.gov.uk — Gas Safety (Installation and Use) Regulations 1998, regulation 3