Underfloor Heating


Next up in this blog series is a few tips for those who are thinking about installing underfloor heating.

There are many advantages to underfloor heating. The main one is that it means that you don’t need any radiators taking up space on the walls. Also, since heat is coming through the floor and rising upwards, you don’t lose heat to the top of the room as can often happen with radiators. This is particularly the case with large buildings that have high ceilings like schools and industrial buildings.

Another advantage is that because having underfloor heating means that your floor acts as a great big radiator, the flow temperature of the water can be kept low which can aid the efficiency of your boiler or heat pump.

Underfloor heating is ideally suited to new builds. The first reason for this is obvious. Installing UFH is much easier when you don’t have to rip up the existing floor to install the pipes as you would on a retrofit. The second reason isĀ that, as mentioned above, the flow temperature of UFH can be kept quite low. This is particularly the case for new build properties, assuming they comply with modern building regulations which basically packs in more insulation than you can shake a stick at. As the property is heavily insulated, you don’t lose much heat and therefore a low flow temperature will work fine. UFH can still be used on older properties but you need to be careful that the heat supply will match the load. A professional should definitely be consulted.

Underfloor heating manifold
Underfloor heating manifold

UFH heatingĀ involves laying out and clipping long loops of pipe over an insulated floor covering (this stops the heat going down instead of up). There is usually one loop per room or zone and this is controlled by a thermostat located in that room. The loop is connected to a manifold usually located close to the heat source and the thermostat opens and closes the appropriate valve in the manifold once the zone has reached the required temperature.

Installation of the loops is fairly straightforward for a competent DIYer although care must be taken with pipe sizing and the distances between the pipes. However, lots of suppliers will do a full design for you so it should work out ok. Once everything is in and connected back to the manifold the system must be pressure tested. It is very important that you do this. A concrete screed will cover the pipes. Once the pipes are covered in concrete fixing a leak will involve a LOT of work!

As I mentioned above, UFH works well with a low flow temperature. Care then needs to be taken with the heat source. A normal boiler will heat the water up to 60 or so degrees and then will be blended with cold water to bring it back down to temperature appropriate for UFH. This is particularly the case if there are radiators being added in to part of the building (lots of people go for UFH on the ground floor and radiators on the first and second floors). Obviously, heating water up only to cool it down again is a colossal waste of energy and best avoided!

How can it be avoided? By using a heat pump! Heat pumps operate with a flow temperature of around 40 degrees. This is exactly suited to UFH! If, as in the above scenario, you want UFH and radiators throughout the building, this is still fine for a heat pump as there are many low temperature radiators now available.

People often ask me if a heat pump is financially worth it in gas-grid areas and the answer is yes, if you are installing UFH. With a standard gas boiler, all that heating up and cooling down will lead to high heating bills and inefficient use of resources which can easily be avoided. If its a new build, go for a heat pump with underfloor heating!


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