Water based underfloor heating systems work by pumping warm water through a network of pipes laid within the floor. The floor will warm up and act as the heat emitter, transferring the heat into the room, effectively turning the floor into a large, low temperature radiator. Since the floor area is far greater than that of a radiator, a lower temperature is required, which offers an even heat distribution throughout the room.
Underfloor heating offers unrivalled comfort over traditional systems. This is due to the even heat distribution, and the high proportion of radiant heat emitted from the floor, around 60% radiant heat, (the remainder of the heat transfer is via conduction and convection).
Savings of between 10%-20% can be found depending on primarily, ceiling height, over traditional systems. Strong convective currents aren’t present, so high temperatures at high levels are absent, hence there is an increase in fuel economy and this also benefits the environment. The increased radiant temperature of the environment (due to the heated floor) means that it is possible to achieve the same comfort conditions with a lower air temperature.
The Chartered Institute of Building Services Engineers (CIBSE) recommend using a 1 to 2° lower design air temperature in standard domestic rooms to achieve the same comfort conditions when using underfloor heating, compared to a traditional radiator system. The only exceptions are bathrooms and en suites where it is standard practice to use the same design temperature. This is due to the higher ventilation rates, a lower available active floor area and the room usage. Towel rails are recommended to supplement the UFH in these areas. Fig 2 below shows a temperature profile of 1) an UFH system and 2) a traditional convective system.
Figure 1 Figure 2
Advantages of Pro Underfloor
- Ideal for buildings with high ceilings – the heat is at the level of the occupants
- Silent in operation – no noisy expansion from radiators
- Energy efficient – Save on running costs and reduce environmental impact when compared to traditional radiator systems
- An even heat distribution will ensure a uniform heat distribution throughout
- The temperature profile is very close to ideal human comfort levels and offers unrivalled comfort for the building occupants
- Maintenance free – no annual maintenance required
- High efficiency boilers can take advantage of the low return water temperatures
- Allows for freedom over internal decor – no radiators wasting valuable living space
- The reduced convective dust levels mean increased air quality – particularly important for those with allergies
Air Temperature Controls
Electronic thermostat(s) are used to control the temperature of each room or zone. A zone is defined as an area that has one or more coil dedicated to heating the area. A coil can heat an area up to 14m square, so large area may require two or more coils. Packs are available that have one programmable thermostat (which offers time and temperature control via the thermostat itself) for heating single areas, such as a one room extension or a conservatory. In a typical ground floor, several thermostats would be used to control the temperature in the different rooms. In this situation, a time clock will also be supplied for controlling the system.
A zone is an area that requires its own thermostat to control the temperature of the room. In the example below the room has 3 zones and hence 3 thermostats. The example shows the WC linked in with the hall way with one thermostat controlling the temperature of the two rooms.
Due to the reduced floor area and increased ventilation rate, in a bathroom or an en suite we recommend supplementing the heat with a thermostatically controlled towel rail. The UFH within a bathroom or an en suite should be controlled with the nearest adjacent zone. For example, an en suite should be controlled with its corresponding bedroom and a bathroom should be controlled by the hall or landing thermostat
Water Temperature Controls
The UFH will require a low water temperature, usually 35-45°C. To achieve this temperature we must blend the water taken directly from the boiler (typically around 80°C) with the low temperature water from the return of the underfloor heating circuits. To achieve this, we use the Control Pack, which is supplied pre-assembled ready to be bolted onto the manifold, which is the distribution point for the UFH. Both of which are included within every Pro Underfloor Pack.
The heat output on an underfloor heating system is determined by the difference in floor to air temperature; the greater the difference between the two, the greater the output. When the pipe work is installed in a screed floor it is possible to achieve a maximum output of 100W/m². This is based on a floor surface temperature of 29°C and an air temperature of 20°C (as stated within BS EN 1264).
In a new build which is insulated to comply with Part L of the Building Regulations, the heat requirement is likely to be around 40-50W/m². In a poorly insulated building, or an area where there is an unusually high amount of glazing, such as a conservatory, additional heating may be required during mid winter conditions.
There are a range of factors that will influence the output of the system; the pipe diameter used, the distance between the pipes, the temperature of the water flowing around the system, the temperature drop across the pipe circuits, the floor make up and the floor coverings.
Floor Coverings and Insulation
A range of floor coverings can be used with UFH, however, thought should be given with regards to which is the most suitable solution. As the resistance of the floor covering increases, the water temperature that flows around the system must also increase, to overcome this resistance of the floor covering. For this reason, ideally a covering such as stone, marble or ceramic tiles would be used, however other floor coverings can be used. The following section gives a brief over view of some of the choices available and also the considerations that are required. We would always recommend contacting the manufacture of the covering you intend to use, to ensure compatibility with UFH systems.
Floor coverings with a high thermal resistance should be avoided with UFH systems. Any floor covering placed on top of a screed should have a TOG rating of, ideally, less than 1.0 but should never exceed 2.5. Note, the TOG rating is equal to 10 times the thermal resistance. Eg If a carpet has a TOG value of 0.8 then it will have a thermal resistance of 0.08 m²K/W. You can down load further information on floor coverings from Downloads.
It is a legal requirement that insulation is fitted within the floor. The insulation should comply with the requirements stated in Part L of the Building Regulations (England and Wales) regardless of whether UFH is installed or not. The relevant Building Standard codes for other countries are as follows:
- Northern Ireland – Technical Booklets F (conservation of fuel and power) and G (sound)
- Republic of Ireland – Parts L & E (as England and Wales)
- Scotland – Section 6 (Energy) and 5 (sound)
Where UFH is installed in an intermediate floor where there is a separate residence below consideration must also be given to the acoustic insulation requirements of Part E. It is also recommended that insulation with a minimum resistance of 0.75m²K/W is fitted in intermediate floors where the room below is heated. This is to ensure the heat rises to the room above.
Floor insulation should be positioned directly below the UFH pipes to minimise the downward losses. In situations where the insulation is below the concrete slab, a minimum of 25mm further insulation should be laid.
In addition to the standard floor grade insulation, it is necessary to fit perimeter insulation, which is to be positioned around all internal walls. This layer acts as a separating layer between the screed and the walls and takes up the slight expansion of the screed while, helping to reduce heat loss to the walls.
Pro Underfloor Packs are water based underfloor heating (UFH) packs which are suitable for both new build and renovation projects where a screed floor is utilised. The packs include all the necessary components to install your underfloor heating. Order your system via one product code, three day delivery as standard.
To determine which pack is suitable for your installation follow the simple selection process by using our pack selector. If you are new to underfloor heating, don’t worry, as this web site includes all of the relevant background information to guide you through, from initial planning, to a successful installation.
In every Pro Underfloor Heating (UFH) pack are all the components required to install your UFH System. The packs include the Pro Underfloor pipework, the manifold, a pre-assembled water temperature controller and pump, pipe clips, edge insulation, a zone valve, a wiring centre, thermostat(s), thermal actuators (if required), installation details, a bevelling tool and a pipe cutter. Further details on all the pack components, how they’re installed etc can be found on this website. Please note that packs do not include a boiler or heat source, primary pipework from the boiler to the manifold or floor grade insulation.
For information and to see photos of the products included, view our components page
Single and Multi Zone Options
Packs are available which contain either a single programmable thermostat (which offers time and temperature control via the one thermostat) or several thermostats and one central time switch. When underfloor heating is installed, the whole floor heats up and effectively becomes your radiator. To control this radiator we need to incorporate some sort of control. On a traditional radiator system, a TRV (thermostatic radiator valve) would usually be fitted to the radiator, which senses the temperature then responds by allowing a flow of water around the radiator. Underfloor heating differs slightly although the concept is the same. If underfloor heating is installed in a single room then the programmable thermostat would wire directly to the underfloor heating pump and to the zone valve. The thermostat would send a demand to run the pump and open the zone which would allow a flow of hot water to the underfloor heating.
In an underfloor heating system that has several thermostats included, the thermostats would be wired back to a wiring centre which is to be fitted above the manifold. When a thermostat calls for heat, a demand signal is sent to the wiring centre which will run the underfloor heating pump, open the zone valve and also open the port on the manifold (controlled by an actuator). When power is applied to the thermal actuator, it will open and allow a flow of water around an underfloor heating coil. This way it is possible to have several thermostats incorporated into your system.
How to Choose Your Pack
There are a number of ways to determine which pack is suitable your project. You can use the online tool, or alternatively, you can use one of the Pro Underfloor brochures to select the most suitable pack. The brochure is available from your local independent merchant or can be downloaded as a pdf from the download centre. The document is titled Pack Selection Process. We recommend you keep your completed copy of the Pack Selection Process brochure as this contains information relating to your project. Please note, once you have decided your manifold location, you should not move it as this may affect the materials required for your project.
To select your Pro Underfloor pack you will need to know the following information:
1) The floor area (m²) of each of the heated rooms
2) The distance from the manifold to the heated rooms (feeds)
3) The number of thermostats you require (zones)
Once the information has been entered, you will be given a product code for your Pro Underfloor Heating pack. You can purchase your Pro Underfloor pack through our online shop.