Water heating Renewables
Getting
into hot

water
Renewable water-heating technologies
are becoming more of an attractive green
option, but there are a number of pitfalls
in trying to marry up different systems.
Ian Vallely reports
A
s higher insulation standards and improved
air tightness have reduced the demand for
space heating, so hot water has become
the dominant heat load in many modern
buildings. As a result, water heating has started to
move rapidly up the energy-saving agenda.
The demand for better energy-saving performance
has, in turn, led to an increase in the use of renewables
such as solar thermal, and ground and air source heat
pumps to preheat the cold water in water-heating
systems. Yan Evans, technical director of boiler maker
Baxi Commercial, says: “Rather than raising the
water temperature using gas from, say, 10
0
C to the
preset temperature of 60
0
C, you can preheat it with a
renewable source. There appears
“For example, if you size a solar thermal system
to be a lack of
correctly, you should hardly have to use any fossil fuel
in the summer months. At other times, if you raise
understanding
the water temperature from, say, 10 to 20
0
C using across the board
solar thermal, you will reduce the building’s carbon
– from clients,
footprint.”
Paul Marsden, UK sales manager of heater
contractors and
manufacturer Lochinvar, agrees that preheating with consultants –
renewables is an environmentally-responsible strategy.
about how to
However, he also sees a danger: “Solar thermal and
water heating are familiar technologies and most
integrate solar
people know they can incorporate both, but there thermal and
appears to be a lack of understanding across the board
water heating
– from clients, contractors and consultants – about
how to integrate the systems to get the best out of them
systems
for the money invested.” > – Paul Marsden
www.cibsejournal.com April 2009 CIBSE Journal 45
CIBSEapr09 pp44,45,46,48_water.indd 45 2/4/09 15:48:48
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