Hot Water
The hot water from the boiler is piped to surrounding
buildings, where heat exchangers
transfer the energy into the central heating
and hot water systems within each building.
The hot water leaves the boiler at 85ºC and
returns from the “primary circuit” a little cooler,
at about 70ºC. The secondary domestic hot
water systems typically have an output temperature
of 80ºC and return temperature of
70ºC.
The heat exchangers used in each building
are manufactured from stainless steel by Alfa
Laval. They consist of a series of thin corrugated
plates which are brazed together with
copper. The plates are then supported in a
rigid frame so that a series of parallel flow
channels are created between the plates.
There are two separate fluids circulating
through each heat exchanger (i.e. those from
the boiler house an those circulating around
each building) with one fluid travelling through
the odd numbered channels and one flowing
through the even numbered channels. In this
way heat is rapidly transferred between the
two fluids.
Boiler House
Pipe and Heat Network
Heat Supply & Emissions
A heat meter measures the amount of energy used
by each customer, and the local community based
company sends them monthly heating bills. Kielder
Community Enterprise Ltd. Has been established as
a community-owned energy service company or
“ESCO”.
The boiler produces very little noise, smoke or ash.
Visitors sometimes cannot even tell when it is running
Emissions from the chimney are mainly composed of
water vapour: total emissions are expected to be
less than a single household coal fire (emissions
quality will also differ, as burning wood fuel will not
release sulphur dioxide). The few wheelbarrow loads
of ash produced each year will be used as a fertiliser
to mix with compost for the village gardens and allotments.
Because wood fuels are carbon neutral (i.e. the carbon
dioxide produced on combustion is equivalent to
that absorbed during the life of the plant) the avoided
carbon emissions from this scheme have been estimated
at about 57 tonnes CO2 per year. This figure
is based on a comparison with the alternative fuel
which would be heating oil.