Heating & renewables

Underfloor Heating Installation Guide

Name: TradePlanr
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Author: TradePlanr

Underfloor heating is a low-temperature system, which makes it a natural partner for heat pumps — but only if the design, the screed and the commissioning are done properly.

Updated 23 Aug 20269 min read

Underfloor heating (UFH) turns the whole floor into a large, low-temperature emitter. That gives even, comfortable heat and pairs beautifully with heat pumps and condensing boilers, because it works at flow temperatures well below a radiator system.

This guide covers the decisions that make or break a wet UFH install: choosing wet or electric, pipe spacing and floor construction, the manifold and controls, and the commissioning that proves it works before the floor goes down.

Key takeaways

Wet UFH suits whole-house and new-build heating; electric mats suit small retrofit areas like a bathroom.
Pipe spacing and floor construction set the output — closer spacing gives more heat, useful near cold perimeters.
UFH is a low flow-temperature system, which is why it partners so well with heat pumps.
The manifold, actuators and per-zone thermostats let you balance and control each loop independently.
Pressure-test before screeding and commission the system properly — then issue the commissioning certificate.

Wet vs electric

Wet (hydronic) UFH circulates warm water through pipes in the floor and is the choice for whole-house heating and new builds, where it can be the primary heat source. Electric UFH uses heating mats or cable and is best kept to small retrofit areas — a bathroom or kitchen — where running the water pipework would be disproportionate.

For anything driven by a heat pump or acting as the main heating, wet UFH is almost always the answer, because it delivers a lot of heat at a low temperature across a large area.

Pipe spacing, floor build-up and output

The heat a floor gives out depends on the pipe spacing, the flow temperature and the floor construction above. Closer pipe centres put out more heat, which is why you tighten the spacing at cold perimeters and under large glazed areas, and open it up in the middle of a room.

Floor build-up matters just as much: a screed floor stores and spreads heat evenly but responds slowly, while a suspended-floor or low-profile system responds faster but needs careful insulation beneath to drive the heat upward, not into the structure below.

Size it like an emitter

Treat each UFH zone as an emitter that has to meet the room's heat loss at your design flow temperature. If the sums do not add up at a low flow temperature, tighten the spacing before you raise the temperature.

Manifold, zoning and controls

The manifold is the heart of a wet system: it feeds and returns every loop, carries the flow meters you use to balance them, and hosts the actuators that open and close each zone under thermostat control. Balancing the loops so each delivers its designed flow is what stops one room baking while another stays cool.

Blend the flow temperature down to the UFH design figure — via a mixing valve or the heat source's own low-temperature output — and give each zone its own thermostat so rooms can be controlled independently. Good controls are the difference between comfort and constant fiddling.

Commissioning and handover

Pressure-test the pipework and leave it under pressure before and during screeding, so any damage from the screeding gang shows up immediately rather than after the floor has set. Once the screed has cured, follow a commissioning warm-up curve to bring the floor up gradually and avoid cracking.

Balance the loops to their design flows, set the controls, and record it all on the commissioning certificate for the customer. That document proves the system was set up correctly and is your reference if anyone questions performance later.

Certificate on site, stored on the job

TradePlanr generates the underfloor heating commissioning certificate as a PDF, filled and signed on site and stored against the job — no writing it up back at the office.

Frequently asked questions

Is underfloor heating better with a heat pump?

They pair very well. UFH is a low flow-temperature system spread over a large area, which is exactly the condition a heat pump runs most efficiently at. It is often the natural emitter choice on a heat pump install.

What pipe spacing should I use?

It depends on the room's heat loss, floor construction and design flow temperature. Tighten the centres at cold perimeters and under glazing where more output is needed, and open them up across the middle of the room.

Do I pressure-test before or after screeding?

Pressure-test before screeding and keep the pipework under pressure during the pour, so any damage shows up straight away rather than after the screed has set over it.

From guidance to action

Underfloor heating commissioningIssue the UFH commissioning certificate on site as a PDF.Free calculatorsHeat loss, flow rate and system sizing calculators for the numbers behind the design.TradePlanr for heating engineersCommissioning certificates, quotes and invoicing built for heating work.