Single Room Screed Kit – High Output Water Underfloor Heating System

The in-screed water underfloor heating system offers several advantages, including even heat distribution, reduced energy consumption, and the ability to use various floor coverings such as tiles, stone, laminate or carpet. Installation can be more involved and will require careful planning during the construction or renovation phase of a building. It’s important to consult with professionals to ensure proper design and installation for optimal performance.

High output underfloor heating systems are designed to be installed at 150mm pipe centres, making them suited to rooms with higher heat loss or when the system is fed by a heat pump. The single room kit can heat one room independently, or several rooms together at the same temperature, up to 100sqm.

To maximise the output of your heating system, consider the following when choosing the floor finish:

Carpet: do not exceed 2.5 tog rating carpet & underlay combined
Engineered Wood & Laminate: do not exceed 25mm in depth
Tiles & Stone: advise the inclusion of a decoupling layer (Ditra Mat or similar) to accommodate different expansion rates
Vinyl & Karndean: ensure a smooth, level surface before bonding flooring

IMPORTANT: when using wood-based flooring, a floor probe MUST be included to limit the floor temperature to 27°c.

What is in-screed underfloor heating?

An in-screed water underfloor heating system is a type of hydronic (water-based) underfloor heating system installed within the floor screed of the building. The system consists of a network of pipes which are pinned to a PIR insulation board then encased in a screed layer of concrete or a similar material. The screed acts as a thermal mass, helping to distribute and retain heat efficiently.

Here’s a breakdown of the main components and the general installation process:

Pipes: High-density polyethylene (HDPE) or cross-linked polyethylene (PEX/PERT) pipes are most commonly used for the water circulation system. These pipes are durable and can withstand the temperature variations involved in heating.

Manifold: The system includes a manifold, which is a central distribution point that connects the heating pipes to the heat source (such as a boiler or a heat pump). The manifold allows for precise control of the flow of the water circulating through the pipes.

Pump: This is responsible for circulating water through the underfloor heating system and maintains a consistent flow of warm water from the heat source to the pipes embedded in the floor, and then back to the heat source for reheating.

Mixing Valve: The mixing valve is crucial for controlling the temperature of the water circulating in the underfloor heating system. It mixes hot water from the heat source with cooler water from the return loop to achieve the desired low temperature for the underfloor heating system.

Floor Screed: The pipes are embedded within the floor screed, which is a mixture of sand and cement or other suitable materials. The screed is poured over the pipes, providing a smooth and even surface while also serving as a thermal mass.

Heat Source: The heat source for the system is typically a boiler, a heat pump, or another water heating system. This source heats the water that circulates through the pipes, transferring heat to the floor and, consequently, the room.

Thermostat and Controls: A thermostat is used to regulate the temperature of the floor heating system. It allows users to set the desired temperature and ensures that the system operates efficiently.