Compatibility of heat pumps with underfloor heating.

[John Cantor]

A topic of concern to me is that of the compatability of heat pumps with current underfloor heating design.  One vital piece of information to be taken into account is that the energy efficiency of a heat pump system improves dramatically if the temperature of the water being heated is kept to a minimum.   Standard underfloor heating is designed to take water at 50C. Reducing this to 40 or 35C is possible, particularly in very well insulated buildings, this involves more pipe, more parallel circuits and therefore bigger manifolds, so costs are increased. However, this is well worth it if a long-term view is taken.   So far, I have come across very few underfloor companies willing to embrace this issue and tend to see it as a bit of a nuisance. 

A further feature, weather compensation, is in my view, a vital part of the control system of a heat pump, this alone reduces the average heated temperature significantly and could be retro-fitted. But the floor installation itself, once laid, cannot be modified.  I am concerned that many underfloor systems currently being installed may eventually be connected to heat pumps. Some time in the future people will be saying ‘if only it was designed for a lower temperature’, and probably also wishing that the thermal insulation below the floor was doubled.   If you want to get the very best from a heat pump connected to underfloor, my advice is tread carefully and get several opinions.  Better information on this topic is clearly needed.

John Cantor
johncantor@heatpumps.co.uk 
http://www.heatpumps.co.uk

[David Olivier]

Perhaps the maximum temperatures which may be used should be made a legal requirement. In Denmark and Sweden since about 1980 even radiator systems have been designed for peak supply and return temperatures of no more than 60 and 40 deg C.

I agree about weather compensation but it works better with continuous heating. The UK psyche is still attuned to intermittent heating. This may slowly be changing in modern low energy buildings (which don't heat or cool rapidly).

[Author]

Posts