Instead of hot radiators, the entire floor becomes a gentle heat source.

The 3 Main Types of Underfloor Heating

1. Electric (Direct)

Electric cables or mats sit under the floor and heat up when powered.

Best for:

• Bathrooms
• Small rooms
• Retrofits

How it works.

• Electricity heats wires
• Heat transfers through the floor
• Room warms quickly

Key facts.

• Fast response (30–60 mins)
• Runs at ~25–31°C floor temp
• Expensive to run

Running costs

• ~£0.23–£0.31 per m² per hour

Think! cheap to install, expensive to run

2. Water (Wet) Gas Boiler

Warm water flows through pipes in the floor, heated by your boiler.

Best for:

• Whole house systems
• Renovations or new builds

How it works

• Boiler heats water
• Water circulates through pipes
• Floor stores and releases heat slowly

Key facts

• Lower temperatures than radiators (~35°C vs 60°C+)
• Slower to heat, but stays warm longer
• Much cheaper to run than electric

Running costs

• ~£0.06–£0.10 per m² per hour

Think! more upfront cost, cheaper long-term

3. Water (Wet) – Heat Pump (Best Option)

The basic idea.

Same pipe system — but powered by a heat pump instead of a boiler.

Why it’s ideal.

Underfloor heating works at low temperatures, exactly how heat pumps like to run.

Key facts

• Most efficient setup
• Perfect for modern homes
• Works with solar

Running costs

• ~£0.04–£0.07 per m² per hour

Think! Highest efficiency, lowest running cost.

Types of Systems (What’s Under Your Floor)

Electric systems.

• Heating mats (most common)
• Loose wire (flexible layouts)
• Foil systems (for wood/laminate)

Pipe types.

PEX / PE-RT plastic pipes (most common) Flexible, durable, long lifespan (50+ years typical)

Installation types

1. Screed (best performance)

• Pipes buried in concrete/screed
• High thermal mass
• Slow but very efficient

2. Low-profile systems

• Pre-formed boards or plates
• Faster install
• Slightly less efficient

3. Retrofit overlay

• Thin systems added on top
• Minimal floor height increase

Screed Types (important for performance)

• Traditional sand/cement
• Cheaper
• Slower heat transfer
• Liquid screed (anhydrite)
• Better heat transfer
• Faster response
• More common in modern installs

Screed acts like a heat battery.

Temperatures (what to expect)

System	Flow Temp	Feel
Radiators	55–70°C	Hot/cold swings
UFH (gas)	35–45°C	Steady warmth
UFH (heat pump)	30–40°C	Very stable
Electric	Surface-based	Fast but less efficient

Lower temps = higher efficiency,

Manifold (water systems only)

This is the distribution hub:

• Splits water into zones (rooms)
• Controls flow to each loop
• Includes pumps, valves, actuators

Think: the heart of the system

Thermostats

Basic

• On/off room control

Smart / zoned

• Each room controlled individually
• App control
• Scheduling

Weather compensation

• Adjusts flow temp automatically
• Essential for heat pumps
• Improves efficiency massively

Installation Costs (UK typical)

Electric

• £60–£120 per m²

Water (wet)

• £90–£190 per m²

Full house installs

• £5,000–£15,000+ depending on size

Running Costs Summary

System	Cost to run	Best use
Electric	High	Small areas
Gas UFH	Medium	Whole house
Heat pump UFH	Low	Best overall

Water systems are significantly cheaper to run than electric

Fault Finding (what goes wrong)

Common issues

1. Cold spots

• Air in pipes
• Poor pipe spacing
• Insulation missing

2. System not warming up

• Wrong flow temperature
• Controls set incorrectly
• Screed still drying (new installs)

3. High running costs

• Poor insulation
• Incorrect controls
• Running like radiators (on/off)

4. Electric failure

• Broken cable
• Faulty thermostat

How to Run Underfloor Heating Properly

This is where most people go wrong

DO:

• Run low and steady
• Keep consistent temperatures
• Use zoning properly
• Let screed store heat

DON’T:

• Turn it on/off like radiators
• Expect instant heat
• Over-adjust thermostats

It’s a slow, continuous system

Solar + Heat Pump + UFH (The Ideal Setup)

This is the “gold standard”:

• Solar PV → powers heat pump
• Heat pump → feeds UFH
• UFH → runs at low temps

✔ Lowest running costs
✔ Highest comfort
✔ Future-proof system

The Bigger Picture

Underfloor heating works best when combined with:

• Good insulation
• Heat pumps
• Weather compensation
• Smart controls

Simple summary

• Electric = easy, but expensive
• Water + boiler = good balance
• Water + heat pump = best overall

Final takeaway

Underfloor heating isn’t just a heating system — it’s a different way of heating your home.