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BTD Plumbing & Heating
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Copper pipework being brazed in situ beneath floor joists during an underfloor heating first-fix
Even, silent, efficient heat

Wet underfloor heating,designed and commissioned to run right

New-build zones, extensions and full retrofit underfloor heating, designed around your flooring build-up, plumbed with the correct pipework, balanced at the manifold and commissioned properly.

18 years' experience · Manifold-balanced · Compatible with oil and gas boilers

  • 18 years
    Experience
  • £2m cover
    Public liability
  • Pressure & flow
    Pipework tested
  • Fully valid
    Warranty
  • Free
    Written quote
Overview

A straight explanation of what we do, and why it matters

Done well, wet underfloor heating is the quietest, most comfortable, most efficient way to heat a room. Done badly, it's a permanent, unfixable disappointment sealed under a tiled floor.

Back to home
What it is
Design, installation and commissioning of wet (hydronic) underfloor heating, single-zone extensions, multi-zone whole-house systems, retrofits over existing floors and new-build slabs. Manifolds, actuators, thermostats, zoning and boiler integration.
Who it's for
Homeowners across Marlborough, Calne, Royal Wootton Bassett, Swindon, Broad Town, Wroughton and the wider rural Wiltshire area, kitchen and utility extensions, full ground-floor retrofits, new-builds and barn conversions.
When you need it
When you're extending, refitting a kitchen or bathroom, replacing floors or building new. Also the right moment when a room is stubbornly cold and radiators can't be sized properly for the wall space available.
Why professional matters
Underfloor delivers a lower, more even flow temperature to a much larger emitting surface than a radiator ever can, which means condensing boilers stay in the condensing band for far more of the year. That's where the efficiency comes from. But it only works when the design, pipe spacing, insulation, screed and controls are all right.
The cost of leaving it

What happens when it's ignored

Underfloor heating that doesn't work is often the most expensive DIY story we hear.

Risks & escalations
  • Wrong pipe spacing gives cold stripes across the room, visible on a thermal camera, permanent to fix.
  • No or poor insulation under the pipework sends most of the heat downwards into the ground.
  • Wrong screed depth or type gives thermal lag so long the system can't respond to weather changes.
  • Undersized manifold or missing balancing valves leaves the far-corner room cold forever.
  • Direct connection to a boiler running 70°C+ flow temperature will crack most types of screed. A blending valve isn't optional.
Common mistakes
  • Buying an underfloor 'kit' online and hoping the tiling team lays it right.
  • Skipping the pressure test before screeding. A pin-prick puncture found after the tiles are down is a nightmare.
  • Using room stats intended for radiators with actuators that never quite match. Poor comfort and constant cycling.
  • Adding underfloor to an existing high-temperature system without a proper blending set. Either the underfloor overheats and cracks the screed or the radiators run cold.

It's a system that rewards proper design and installation, and punishes shortcuts, permanently.

Our process

A clear, five-step system, no surprises

  1. Step 1
    Design and heat-loss calculation

    Per-room heat loss, pipe spacing and loop lengths designed to deliver the required output at low flow temperature.

  2. Step 2
    Manifold and control selection

    Right number of ports for your zones, correct actuators, thermostats and, where needed, weather-compensating controls.

  3. Step 3
    Pipework installation and pressure test

    PE-RT / PE-Xa pipe pinned or clipped to spec, tails brought back cleanly to the manifold, pressure-tested before screed goes down.

  4. Step 4
    Screed compatibility and warm-up schedule

    Correct screed depth, cure time and initial warm-up schedule to avoid cracking | coordinated with your builder or tiler.

  5. Step 5
    Commissioning and balance

    Each loop balanced individually at the manifold, controls set up, walk-through with you, everything written up.

The benefits

Concrete outcomes, not vague promises

Even, quiet warmth

No radiators to work around, no visible plumbing, no cold spots | one big radiator across the whole floor.

Efficient with modern boilers

Low flow temperatures keep condensing boilers in their condensing band far more of the year | real fuel savings.

Room-by-room control

Multi-zone control means the kitchen, utility and bathroom can each run to their own schedule and temperature.

Wall space back

Freeing walls of radiators and pipework opens up kitchen, bathroom and living-room design options.

Pressure tested before screed

Every loop hydraulically tested and left under pressure while screed cures | leaks caught before they're buried.

Boiler integrated properly

Blending valve, correct flow temperature, controls integrated with existing radiators. Not a bolt-on.

In detail

The technical stuff, explained straight

Where the theory meets the van. Materials, methods, brand differences and the specific situations we deal with week in, week out across Wiltshire.

Screed builds vs low-profile retrofit systems

New-build and extension jobs typically use a sand-and-cement or liquid screed poured over pipework laid on insulation. That builds a substantial thermal mass, slow to warm but very stable once running. Retrofit systems (aluminium spreader plates, or low-profile pipe-in-panel products laid over existing floors) allow underfloor heating to be added to a room without lifting the floor structure, thinner build-up, faster response, slightly higher flow temperatures required. We'll advise on which is right for your build-up at survey.

Manifolds, blending and controls

The manifold is the brain of an underfloor system. Each loop connects individually with a flow meter (for balancing) and an actuator (driven by that zone's thermostat). A blending valve mixes hot flow from the boiler with cooler return water to hold the underfloor flow temperature at the correct, low value (typically 35–45°C). Get the blending wrong and either the floor is cold or the screed is at risk. Controls range from simple room thermostats up to weather-compensating multi-zone systems that talk to modern boilers.

Underfloor with oil boilers

Modern condensing oil boilers integrate cleanly with wet underfloor heating via a blending set. The low flow temperature and constant modest demand actually keeps a condensing oil boiler running efficiently through the shoulder months when a radiator-only system would short-cycle. A very common upgrade in Wiltshire is a new oil boiler paired with new ground-floor underfloor heating, done together, one visit, one warranty.

Underfloor with gas boilers

Same story, gas side. Modulating condensing gas boilers deliver excellent performance at underfloor flow temperatures. Where an existing gas system has both radiators (upstairs) and underfloor (downstairs), we install a two-temperature manifold or a two-port zoning arrangement so each side runs at its correct temperature, a common source of comfort problems when done as a botched retrofit.

New build, extension and retrofit differences

New build: full design freedom, correct insulation depth, proper screed. New extension: coordinate with builder for insulation and screed thickness; brought back to a new or extended manifold. Retrofit: low-profile panels or spreader-plate systems suit existing joisted or solid floors; expect slightly higher flow temperatures than a full slab system, and take insulation seriously, otherwise you're heating the floor void. We'll be honest at survey about what a specific room can realistically deliver.

FAQs

The questions we're asked most

Can't see yours? Give us a ring; we don't do sales scripts.

Call 07920 042880
Depends on floor area, zones, boiler integration and whether it's new build, extension or retrofit. We survey then quote in writing. Free, no obligation.
Zoned central heating manifold with low-loss header and multiple circulator pumps installed by BTD
Free written quote · no pressure

Thinking about underfloor heating? Get it designed properly.

Book a free survey. We'll walk the room with you, talk build-ups honestly and quote in writing.

  • Gas Safe 529962
  • OFTEC C11108
  • 18 years' experience
07920 042880Request a Free Quote
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