Wet Underfloor Heating Systems Explained
Wet underfloor heating circulates warm water at 25-35°C through pipes embedded in your floor, delivering the most even warmth at the lowest flow temperatures. At these temperatures, your heat pump achieves COP values of 4.0-5.0 — 20-30% more efficient than with radiators.
Wet UFH is the technical side of the heat pump and UFH pairing. For comparison with radiators, see UFH vs radiators. Pillar: radiators and heat pumps.
How Wet UFH Works
The heat pump heats water to 25-35°C. A manifold distributes it to individual room circuits of 16mm pipes laid in the floor. Each circuit has a flow meter and actuator for independent zone control. The large floor area means low water temperatures still deliver adequate room warmth.
Screeded vs Overlay Systems
| Feature | Screeded | Overlay |
|---|---|---|
| Total depth | 65-75mm | 15-25mm |
| Thermal mass | High (stores heat) | Low |
| Response time | 2-4 hours | 30-60 minutes |
| Best for | New build/major renovation | Retrofit over existing floor |
| Cost per m² | £30-£50 | £40-£70 |
The Manifold
The manifold is the control centre of the UFH system. It distributes water to each room circuit, balances flow rates, and houses the actuators that open/close circuits based on zone thermostat demands.
Compatible Floor Coverings
- Tile and stone: Best heat conductors — ideal for UFH
- Engineered wood: Works well — check manufacturer's UFH approval
- Laminate: Good — ensure it is UFH-rated
- Carpet: Works but reduces efficiency — use low-tog carpet and underlay (combined max 1.5 tog)
Combining UFH with solar panels achieves near-zero carbon heating at the lowest possible cost.
Frequently Asked Questions
What is a wet underfloor heating system?
A hydronic system circulating warm water through floor-embedded pipes, heated by the heat pump.
How thick is a wet UFH system?
Screeded: 65-75mm. Overlay: 15-25mm above existing floor level.
Wet underfloor heating is the most efficient emitter for heat pumps. Connects to the complete UFH guide, emitter choices, and running costs. Solar panels complement UFH for near-zero energy costs.