Underfloor heating is not a new technology – there is archaeological evidence in Manchuria (north-eastern China) dated to 5200 B.C.E. of floors used for living being heated underneath by flues channelling the exhaust from fireplaces.

Around 500 B.C.E., the ancient Romans developed a system that works on much the same principles called hypocausts, whereby raised floors rest upon pillars called pilae stacks, between which the exhaust of furnaces circulates.

Underfloor heating has gained popularity in the UK over the last 10-15 years.

Water-based underfloor can connect to any heat source. A pipe is laid in the room at typically 150mm centres, and warm water is passed through the pipe when the thermostat calls for heat. A room may have several coils of pipe; and these are connected to a manifold, which has a flow and return connection for each pipe. When the thermostat for that room calls for heat, the actuator for that zone opens and allows the water through. The water is generally at 40-45 degrees C.

Underfloor heating systems generally work more efficiently than radiator systems due to the lower flow temperatures. The floor is the heat emitter; and as it has a very large surface area, it can work efficiently.

1. New build

Historically, this was where underfloor gained popularity in the UK. The new build systems are very simple to install, and cost-effective. Generally people have underfloor installed on just the ground floor, and this is normally a SCREEDED system.

New Build Screed System

New Build First Floor Clippa Plate System

2. Renovation

We can offer renovation products; and these typically offer two main benefits:

• High heat output
• Low height build up

These products can be either ‘wet’ or ‘dry’. We offer both. Renovation products are generally more expensive, due to a larger number of components.

Tri-panel Underfloor Heating System

Dry System – LoPro 10

These again are mainly fitted to the ground floor; but we can also advice on first-floor renovation products. These could be overlay systems or between-the-joists systems.

We only use quality products, and we ensure the underfloor heating system has been designed to fit the property. This means the correct amount of pipe per room, at the correct spacings, and the correct flow rate. This is set up on the flow setters, which are on the manifold. The energy going into the room is the flow rate multiplied by the difference between the flow and return temperatures of that room.

The design will give full tube layout drawings, manifold locations and sizes and also thermostat locations.

The manifold or manifold locations are important, as each room has run-back pipe to the manifold, and this should be minimised. You should also insulate the pipe in these runback areas, as you want the energy to enter the room and be controlled by the thermostat. The runback areas are generally hallways; and sometimes the pipes will need to be spaced closely in these areas. Again, using a design may suggest using a second or third manifold in different locations within the house.

Above each manifold will be a wiring centre; and this links the thermostats with the actuator. When the thermostat calls for heat, the wiring centre sends the electrical signal to open the actuator or switch.

Manifold

Generally when the building is being built, or during a major renovation.

Ideally a conductive surface such as ceramic or polished concrete will give the best outputs.

The next best is engineered flooring such as oak (don’t use real wood flooring), and then Karndean and similar. When using Karndean and similar, make sure that floor sensors have been installed – this means the floor is protected and should it get too hot, it will shut the system down for that room.

If you want carpet, then you will need a special underlay with a low tog rating (typically 1.5). The use of carpeted flooring would mean that the system would have to work harder to drive the heat through the insulative underlay.

The thermostat is the brain behind the underfloor heating system, controlling when the heating switches on and off. We can offer a wide range of thermostats, from basic dials (bi-metallic strip type) to more sophisticated smart thermostats.

We generally use Heatmiser products, which are the market leaders for underfloor heating controls. We recommend hard-wired thermostats, but can also offer wireless battery-powered thermostats. Some of the new products can work with home automation systems, such as Apple Home kit.