Future-Proofing Underfloor Heating

A standard boiler system works on a short, sharpstage, it is also worth looking at practical issues to
shock premise with an instant response to the callsee if heat pump technology will be suitable, as
for heat. A heat pump - whether air source orthere are particular installation requirements. For
ground source - delivers a constant flow of heat.example, an area approximately two and a half
The efficiency comparison is rather like driving atimes the size of the property is needed to lay
car stop/start through town as opposed to athe ground loops for a GSHP. An ASHP requires
smooth, even cruise at one speed.space outside, pipework and wiring from the
Conventional boilers produce hot water at aexternal unit back into the property and both
temperature in excess of 65°C comparedtypes require a plant or utility room to house the
with 35 - 45°C from a heat pump. Theseequipment.
lower temperatures will adversely affect theInstaller Perspective
performance of underfloor heating (UFH) if theyDominic Taylor-Lane of Purus Navitas, an
are not factored in prior to installation.experienced installer of underfloor heating and
Significant Factorsheat pumps recently worked on a refurbishment
The first consideration is the amount of pipe inproject where the householders decided to install
the floor and the spacing required. A greatera conventional boiler with a view to changing to a
amount of pipe may be required for use with aground source heat pump in the future.
heat pump due to the lower water temperature.Dominic explains how the system was
Tube spacing for a conventional boiler mightfuture-proofed in this instance. 'The owners have
typically be at 200mm centres and a heat pumpthe space for boreholes so, although a
at 150mm centres. However, there are so manyconventional boiler has been installed, the ground
variables that this can only be determined whensource heat pump is an option for later. For this
the design has taken into account such factors asreason the plant room was purpose-built to be
room size, glazing and floor covering.large enough to house a ground source heat
It is important to establish what floor covering willpump and buffer cylinder. Pre-insulated pipe was
be used when the pump is installed. Many floorrun into the plant room terminating in a manhole
coverings including most tiles, slate, laminates andcover close to the proposed borehole site to
solid wood work well with UFH. Carpet andminimise any future disturbance to the work
underlay are acceptable as long as a tog of morealready done.'
than 2.5 is not used.Of insulation requirements Dominic comments 'The
For any underfloor heating installation, levels ofinternal walls were lagged during the refurbishment
insulation are essential to the efficiency of theso in this instance the underfloor heating pipe
system, but when a heat pump is to be used thisspacing specifications made by Nu-Heat were
is even more critical. Insulation levels should ideallysimilar to a normal specification. The first floor
ensure that less than 45 watts of heating areradiators run off a different circuit, but we
required per square metre of floor space.installed oversized aluminium radiators so they will
If the future heat pump system is to includework with a heat pump in future.'
radiators, these must be sized correctly so thatAs increasing numbers of customers think about
they continue to work efficiently after thetheir long-term energy needs, future-proofing is a
changeover. As a rule of thumb, radiators willserious matter. Ultimately, as long as the initial
need to be around one third bigger than whendesign and installation of UFH has taken into
used with a conventional boiler. The alternative isconsideration future integration with a heat pump,
high efficiency radiators that should be sizedthe final system will run efficiently and is likely to
according to manufacturer specification.last for a long time to come.
Along with the future proofing required at design