Underfloor Heating Installation in Charlton

Wet vs electric: which system suits your property

Wet underfloor heating circulates warm water through a network of pipes connected to the central heating boiler. Running costs are significantly lower than electric systems because gas is cheaper per kilowatt-hour than electricity. Electric mat systems use resistance heating and cost more to run but require no wet trades, no manifold and no connection to the boiler circuit. Electric is best suited to single rooms such as bathrooms; wet is preferred for whole-floor heating projects.

Screed vs overlay system: floor height in London flats

A traditional wet screed system requires a 75mm screed poured over the pipe, raising the finished floor level by at least 100mm in total including insulation. In London Victorian and Edwardian flats, this is frequently impractical: door thresholds, skirting heights and staircase geometry are all affected. A wet overlay or batten system using pre-routed panels adds only 15 to 22mm to the floor height and is the standard recommendation for London flat retrofits.

Period properties and floor depth constraints

London period properties present specific challenges for underfloor heating. Suspended timber ground floors require the boards to be lifted and insulation installed beneath the joists before the pipe is laid. Beam-and-block or concrete ground floors allow screed overlay installation but the floor height increase must be managed against existing door thresholds. In first-floor flats and upper floors, structural engineer sign-off is required before adding significant additional dead load from screed.

Combi boiler compatibility and flow temperature

Underfloor heating works best at low flow temperatures of 35 to 45 degrees Celsius, compared with 70 to 80 degrees Celsius for standard radiators. Modern A-rated combi boilers can deliver these low flow temperatures but require a mixing valve or weather compensation control to modulate the output correctly. Weather compensation adjusts the flow temperature automatically based on outside air temperature, reducing gas consumption by up to 15 percent. Older combi boilers without modulating burners may not be suitable for wet UFH without an upgrade.

Zoning, manifold design and thermostats

Each room or area is a separate zone controlled by its own thermostat and actuator on the manifold. A five-room flat might have a five-port manifold with five actuators and five thermostats. The manifold is connected to the boiler flow and return and distributes water to each loop. Individual zone control allows rooms to be set to different temperatures and scheduled independently, which is the primary efficiency advantage of UFH over a single-zone radiator system.

Floor coverings: what is compatible with UFH

Tile, natural stone and porcelain are the ideal floor coverings for UFH because they conduct heat efficiently and tolerate the thermal cycling without damage. Engineered wood is compatible provided the manufacturer specifies UFH suitability and the maximum operating temperature is not exceeded. Solid hardwood and thick carpet are not recommended: solid wood expands and contracts and can cup or gap; thick carpet acts as insulation and prevents heat from reaching the room. If carpet is to be used, select a combined tog rating below 2.5.