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Justin installed this system in early 2008. He
writes:
"Dave and Sue had requested quotations from a number of
Solar Companies to
install a system that would heat both their preinstalled 180 Litre primary
cylinder on the main house and a huge 1500 Litre Thermal Store Secondary
cylinder situated outside the property. This store is used to heat the
newly
converted barn with hot water and underfloor heating, it is also heated by a
Biomass boiler situated outside (see pictures below). It seemed that all
the quoting companies wanted to separate the systems and run them individually
which would have limited the size of the collector array. They basically said
it's not
possible to run the 2 together".
Contrary to this advice, the way Justin installed this
system is exactly what we would suggest. The large collector array
provides the benefit of very rapid heating of the 180 litre primary store (in
full sun more quickly than a typical electric immersion heater would do),
then automatically switches to the large heat store which acts as a heat dump
(without wasting the heat!).
The installation comprises:
180 litre twin oil primary cylinder
1500 litre thermal store secondary cylinder
Resol Flowcon A pump station
Resol BS Pro controller
Resol 3 port diverter valve
3 x 30 58mm Tube collectors
20 l propylene glycol
64m Armaflex HT
Justin continues
"The system is programmed to heat the primary cylinder to 60°C.
This
temperature was partly decided because the water in the area has problems
with scale, this lower temperature would hopefully reduce scale. Once the
desired
temperature is reached the 3 port diverter switches and starts to heat the
huge 1500 Litre Secondary cylinder. As with my previous installs the 'T run'
function played it's part and will load the secondary cylinder rather than
lose the heat currently being stored in the manifold. It is also possible to
change the priority of the cylinders so that the system heated the secondary
first. This is done easily on the controller and takes about 30 seconds. Due
to the design of this system a total of 70 Metres of copper pipework were
installed along with 64 Metres of Armaflex".
The T run function Justin refers to is a facility which
causes the controller to heat the stores out of sequence. This in useful
in poor sun conditions, where the primary cylinder has not reached its preset
maximum (in this case 60°C), but
the secondary cylinder is cooler than the manifold temperature. The
controller will wait for a while to see if the manifold temperature
increases enough to allow the heating of the primary store to continue. If
it does not, then it will switch to the secondary cylinder, utilising heat which
would otherwise be wasted.
Thanks to Sue, Dave and Justin for this information.
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