We are planning a large loft conversion. We have been advised to install zoned water fed underfloor heating. How does this compare with conventional radiators on efficiency? We know it is more expensive to install.

  • Tony Taylor


    This is a fairly difficult question to answer, the efficiency depends on many different factors, usage patterns, heat source, system design etc. all of which can be difficult to nail down.

    You should of course, aim to make the property and the heating system as efficient as possible. Aim to reduce the need for energy in the first place, then invest some research time into the various options available. My website will give you some simple descriptions of how radiators and under-floor heating (UFH) works, see more at http://www.smartgreenengineer.co.uk

    Essentially the difference between the two options is the flow temperature. The radiator system will require flow temperatures of 60 to 80 degrees C, whereas the UFH can operate at much lower temperatures of 40 to 50 degrees C.

    You mention that you are carrying out a loft conversion, so you will probably be connecting the new rooms into your existing system, more than likely radiator circuits fed from a gas or oil fired boiler. All of this means you would benefit from the higher flow temperatures and could choose either option (the UFH manifold will blend the flow and return to achieve 40 to 50 degrees C in each pipe-loop).

    If you are going to install some form of renewable technology, air or ground source heat pumps for example, you will have available the lower flow temperatures and UFH fits best with this scenario. Radiators are possible, however they will need to be oversized to provide sufficient heat into each room.

    Many people choose the UFH over radiators, because it hides all the ugly heating equipment to create a cleaner space. Radiators emit heat from one location in the room, whereas UFH tends to provide an even distribution throughout the space.

    Basically, assuming you are using a gas or oil fired heat source, the quantity of fuel you put in will be converted into a quantity of useful heat for your home, the amount of waste (or lack of) then becomes the issue.

    Hope this helps.


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