What is Rare Plumbing Website?

A bespoke digital atelier providing precision engineering and climate control services for London's most discerning luxury estates.

What is the difference between wet and electric underfloor heating?

Wet (hydronic) UFH circulates warm water through pipes beneath the floor — connected to your boiler or heat pump. Electric UFH uses resistance heating cables or mats powered directly. Wet systems have much lower running costs (especially with heat pumps) but higher installation costs. Electric is suitable for small areas like bathrooms. For whole-home heating in London properties, wet UFH is almost always the correct choice.

How do you calculate heat loss for underfloor heating?

Heat loss is calculated to BS EN 12831 — the British/European standard for heating system design. We assess: floor area, ceiling height, U-value of floor/wall/ceiling constructions, window area and glazing specification, orientation, air change rate and design outdoor temperature (London: -3°C). The result (in W/m²) determines whether UFH can be the sole emitter or whether supplementary radiators are needed. A screed system typically delivers 40–100 W/m² depending on pipe spacing and flow temperature.

What pipe spacing is correct for my property?

Pipe spacing is determined by the required heat output. For well-insulated modern properties, 200mm spacing at 40°C flow temperature typically delivers sufficient heat. For older London stock with less insulation, 100–150mm spacing and 50°C flow temperature is more typical. Specifying 200mm spacing for a poorly insulated Victorian terrace is one of the most common UFH installation errors — resulting in a system that barely warms the room on cold days.

Can UFH work with my existing boiler?

Yes, in most cases. UFH operates at 35–55°C flow temperature vs 65–75°C for radiator systems. A blending valve (thermostatic mixing valve) at the manifold reduces boiler water to the correct flow temperature. Modern condensing boilers work efficiently at UFH temperatures. Older non-condensing boilers can drive UFH systems but without the efficiency benefit. We assess compatibility during a survey.

What smart controls do you install with UFH?

We are Heatmiser-certified installers and the preferred Heatmiser specialist for Central and North London. We install the full NeoHub ecosystem — NeoStat V2 (touchscreen), Neo wireless stats, and underfloor-specific Heatmiser UH8/UH4 manifold controllers. The NeoHub allows up to 32 independent zones with individual scheduling, holiday modes and real-time energy monitoring via the Heatmiser Neo app. We also install Honeywell evohome and Tado for hybrid systems.

How long does UFH installation take?

A typical ground-floor installation in a 3-bed London property takes 3–5 days: 1 day insulation and pipework, 1 day manifold and controls, 1–2 days for screeding (by our screeding partner), and 1 day commissioning and handover. Low-profile overlay systems are faster as they eliminate the screed wait time (3–5 weeks cure) — these are fully functional within 24–48 hours.

Can underfloor heating be installed in an existing property without lifting all the floors?

Yes. Low-profile overlay systems (Warmup Sticky Mat, Polypipe ScreedBoard 20, Uponor Quik&Easy) are as thin as 15–22mm and can be installed over existing screed or timber floors without major disruption. They are ideal for London period properties where floor heights are a constraint. Suspended timber systems (where pipework is stapled between joists from below) require no floor disruption at all but need accessible understorey space.

Do you offer annual maintenance for UFH systems?

Yes — our annual UFH maintenance visit includes: manifold inspection and flow balancing, actuator operation test, water quality analysis (pH, inhibitor, TDS), inhibitor top-up if required, blending valve check and calibration, thermostat/smart control firmware update, and full written report. Annual maintenance is included in our PPM membership plans from £750/year.

Is my underfloor heating covered by the boiler warranty?

No — underfloor heating components (manifolds, actuators, pumps, blending valves) are separate from the boiler and have their own warranty terms from their respective manufacturers. The boiler warranty covers the boiler only. However, poorly maintained UFH can cause boiler faults (e.g. low system pressure from a UFH leak), so annual UFH maintenance protects both systems.

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RARE Plumbing London engineer commissioning an underfloor heating manifold in a luxury London property

UFH Specialists — Heatmiser Certified

Underfloor Heating Installation London — Heat Loss Design & Wet UFH Specialists

London's underfloor heating installation specialists. Heat loss calculations, screed and low-profile overlay systems, Heatmiser smart controls and full commissioning. Gas Safe registered — available 7 days.

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Gas Safe Registered

Available 7 Days

4.7★ Rated

13+ Years Experience

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Available 24/7. Gas Safe registered engineers.

London's Wet UFH Specialists

Engineering-grade installation and diagnosis

Most underfloor heating problems we see were caused at installation — pipes spaced too far apart, too little floor insulation, systems never properly balanced, or filled with London's untreated hard water.

RARE's engineers approach every project — new installation or fault diagnosis — from the physics of the system. We calculate heat losses before specifying pipe spacing. We measure flow rates before claiming a manifold is balanced. We test water chemistry before filling a new system. This is why our installs perform correctly and our diagnostic visits find the root cause, not just the nearest replaceable component.

We are Heatmiser-certified installers and the preferred UFH specialist for private clients across Mayfair, Belgravia, Knightsbridge, Hampstead, Chelsea and Holland Park.

Heat loss calculations & system design

Screeded wet UFH installation

Low-profile overlay retrofit systems

Suspended timber (staple-up) systems

Heatmiser NeoHub installation & zone control

Manifold specification & commissioning

Water quality testing & inhibitor dosing

Pressure testing & commissioning certificates

System boiler + UFH integration

Annual manifold maintenance plans

Get a UFH Survey

We assess your property, calculate heat losses and provide a fixed quote — no charge, no obligation.

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Area Coverage

Mayfair Belgravia Knightsbridge Chelsea Kensington Holland Park Notting Hill Marylebone St John's Wood Hampstead Primrose Hill Westminster

Engineering Fundamentals

Heat loss analysis — why it determines everything

Underfloor heating output is fixed by pipe spacing and flow temperature. Before any pipe goes in the ground, we calculate the heat loss of every room to confirm the system can meet demand. A UFH system specified without this calculation is either undersized (cold rooms) or wildly overspecified (wasted cost). London's mix of period stock and modern extensions makes this step non-negotiable.

Heat Output by Floor Construction — London Property Types

Approximate figures for screeded wet UFH at standard pipe spacings. Actual values require full BS EN 12831 calculation.

Property / Floor Type	U-Value (W/m²K)	Output Required	Pipe Spacing	Verdict
Well-insulated modern extension (100mm floor insulation)	0.09	30–40 W/m²	150–200mm	Comfortable at 40°C flow temp
Standard London Victorian terrace (50mm insulation)	0.18	55–70 W/m²	100–150mm	Requires 45–50°C flow temp
Period basement — stone floor, minimal insulation	0.35+	90–110 W/m²	Not viable as sole emitter	Supplementary radiators required
Low-profile overlay on existing screed	0.22	60–75 W/m²	200mm (fixed)	50–55°C flow temp needed

Pipe Spacing vs. Heat Output — Reference Guide

100mm

centres

Output~100 W/m²

Flow temp50–55°C

Poorly insulated floors, period properties

150mm

centres

Output~75 W/m²

Flow temp45–50°C

Standard residential — most London properties

200mm

centres

Output~55 W/m²

Flow temp35–45°C

Well-insulated modern builds, heat pump systems

250mm

centres

Output~40 W/m²

Flow temp30–38°C

Passivhaus/near-zero energy buildings only

Common installation error: Specifying 200mm pipe spacing across an entire Victorian terrace because it's cheaper and quicker to install. For period London stock with modest floor insulation, 200mm spacing at boiler temperatures delivers roughly 40–55 W/m² — inadequate when room heat loss exceeds 60 W/m². The result is a system that warms the floor without heating the room.

System Selection

Three UFH system types — which is right for your property?

The correct system type depends on floor construction, available depth, response time requirements and whether the project is a new build or retrofit. We assess all three factors during every survey.

Screeded wet UFH

System depth65–150mm total floor build-up

Response time2–4 hours warm-up time

Pipe spacing100–200mm centres

Flow temperature35–45°C

Best for

New builds, ground floor slabs, major renovations

Maximum heat output. Ideal for heat pumps at low flow temperatures.

Low-profile overlay

System depth15–22mm system depth

Response time30–60 minutes warm-up time

Pipe spacing200mm centres (fixed)

Flow temperature45–55°C

Best for

Retrofit projects, first-floor rooms, listed properties

Minimal floor height impact. Compatible with all floor coverings.

Suspended timber (staple-up)

System depthZero floor height impact

Response time1–2 hours warm-up time

Pipe spacing150–200mm centres

Flow temperature45–55°C

Best for

Period homes, listed buildings, upper floors

Pipes fixed between joists from below. No disruption to floor finishes.

Underfloor heating not working? Cold spots or manifold faults?

Our dedicated UFH repairs team diagnoses and fixes cold spots, manifold faults, leaks and balancing issues — with thermal imaging, no floor lifting. See our underfloor heating repairs page →

UFH Repairs

Water Chemistry

Water quality & UFH longevity

London's tap water is exceptionally hard — 300–350 mg/L calcium carbonate. Without treatment, this deposits as limescale inside UFH pipe loops and on heat exchanger surfaces, reducing output and eventually blocking circuits.

We test pH, inhibitor concentration, chloride levels and total dissolved solids on every major UFH visit. Where water hardness is a concern, we recommend integrating a BWT Perla Silk or Harvey water softener on the mains supply — the most effective long-term protection for UFH systems and premium boilers.

Hard water & heating guide

Water Quality Parameters — UFH Systems

Parameter	Ideal Range	Risk if Out of Range	Test Frequency
pH	6.5–8.5	Acidic water attacks copper pipe	Annual
Inhibitor concentration	Manufacturer spec (typically 1:40)	Iron oxide (magnetite) formation	Annual
Chloride content	<50 mg/L	Pitting corrosion of stainless/copper	At install & if corrosion suspected
Hardness (London water ~300–350 mg/L CaCO₃)	<100 mg/L post-treatment	Limescale in heat exchanger & pipe loops	Annual — recommend softener
Total dissolved solids (TDS)	<1000 mg/L	Accelerated corrosion, conductivity problems	Annual

Water quality testing is included in all RARE UFH commissioning visits and annual maintenance plans. Results logged and provided to client.

New Installations

Our UFH Installation Process — 8 Steps

Every installation follows a documented process. You receive a commissioning certificate and pipe layout drawings at handover.

Heat Loss Survey

We calculate room-by-room heat loss to BS EN 12831 standards — accounting for U-values, orientation, glazing area and air change rates. This determines whether UFH is viable as the sole heat emitter.

System Type Selection

Screed, low-profile overlay or suspended timber — chosen based on floor construction, required depth, response time needs and floor covering compatibility (timber, tile, stone or LVT).

Hydraulic Design

Circuit lengths are calculated to stay below 100m per loop to maintain adequate flow velocity. Manifold location, zone boundaries and pipe spacing are specified from the heat loss data — not guesswork.

Floor Preparation

Correct insulation is critical. We install minimum 25mm PIR for retrofit, 75–100mm for slab installs. Inadequate insulation is the single biggest cause of UFH underperformance.

Pipework Installation

MLCP (multi-layer composite pipe) or PEX-A pipe laid in designed patterns — spiral/snail for even distribution. Pressure-tested at 6 bar before any screed or boards go down. Certificate issued.

Commissioning & Balancing

Manifold flow rates set to within ±10% using built-in flow meters. Blending valve calibrated. System filled, flushed, inhibitor dosed and vented. Water quality sample taken and logged.

Controls Installation

Heatmiser NeoHub and NeoStat or wireless sensors installed. Multi-zone scheduling configured. Smartphone app set up and tested on the client's devices before handover.

Handover & Commissioning Record

Full commissioning documentation issued including pipe layout drawings, flow rate records, inhibitor certificate, pressure test certificate and control system user guide.

What you receive at handover

Pressure test certificate · Pipe layout drawings · Flow rate commissioning record · Inhibitor dosing certificate · Controls user guide · Water quality test results

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What our clients say

4.7★ across 120+ verified reviews

"RARE installed UFH across our entire ground floor and integrated it with our Heatmiser system. The heat distribution is perfect — no cold corners, no hot spots. Outstanding engineering."

Alex C.

Belgravia, SW1

"Had persistent cold spots for two years. Two other companies replaced actuators without success. RARE did a thermal camera scan, found a partial magnetite blockage in the north circuit, flushed it and rebalanced. Fixed in one visit."

Fiona M.

Holland Park, W11

"Full UFH across a 4-storey townhouse. RARE designed the system from heat loss calculations, not just estimates. Every zone performs perfectly — and they completed it within the renovation timeline."

George P.

Mayfair, W1

"Needed a low-profile system for our first floor without losing height. RARE specified the right overlay system, managed the entire installation and commissioned it in 3 days. No mess, no drama."

Sarah K.

Hampstead, NW3

Underfloor heating — complete technical guide

Heating System Sludge

Magnetite & contamination guide

Heatmiser Controls

NeoHub & NeoStat specialists

Heatmiser App Not Connecting

Step-by-step fix guide

Power Flushing

Remove sludge from UFH circuits

Hard Water London

Scale, inhibitors & softeners

Water Softener Installation

BWT & Harvey specialists

You May Also Need

Heatmiser Smart Controls

Heatmiser NeoHub installation — up to 32 independent zones from one app.

Power Flushing

Remove magnetite from UFH circuits and restore even heat distribution.

PPM Membership

Include your UFH manifold in an annual care plan from £750/year.

FAQ

Underfloor Heating Questions Answered

Our engineers answer these questions every day. Still not sure? Call us and speak to an engineer directly.

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Property Care Membership

Prefer proactive care? RARE members receive planned servicing, detailed property records and priority access when problems arise. Explore Property Care Membership for professionally managed plumbing and heating maintenance.

Arrange a Property Health Assessment Compare Memberships

Authoritative Sources & References

Wikipedia
Central heating — Wikipedia
Wikipedia — Encyclopaedic overview of central heating systems, heat generation, circulation methods and the history of whole-building heating.
Wikipedia
Boiler — Wikipedia
Wikipedia — Reference on the design and operation of closed-vessel boilers used for central heating and hot water generation.

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Tell us about your underfloor heating

Repairs, cold spot diagnosis, manifold faults, new installations and annual maintenance — all from London's wet UFH specialists. Fill in the form and we'll confirm within 2 hours.

Why RARE for UFH?

Heat loss calculations before any install
Thermal imaging for cold spot diagnosis
Manifold balancing & water quality testing
Heatmiser NeoHub certified installers
Commissioning certificates on every job

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System details

The more we know, the faster we can diagnose or quote.

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Property type

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We'll confirm within 2 hours. For emergencies call 020 7458 4949