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Devon
Solar & Damp Devon
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FAQ's
Flat panels against vacuum tube
Flat panels are ideal if you need solar heating for a certain part of
the year only i.e. the summer. This is because they are efficient only
when directly facing the sun, but as the sun's position changes during
the year, their efficiency will decrease. Vacuum tubes pick up the sun's
radiation even if the sun is not directly angled at the tubes.
Installation
The installation time is generally 2 days assuming that the loft has good
and clear access and that the roof is readily accessible. The system is
best installed on a south facing sloping roof but systems can be installed
on an East/West roofs or flat roofs.
How is it fitted to the roof?
It is fitted over the existing roof surface. Four stainless bands, one
at each corner, slide under the tiles and are fixed to the main roof beams.
Government grants are available
We are provisionally clear skies approved and consequently a residential
customer can obtain a £500 grant from the government. There are
schemes for commercial installation as well - please contact Sirena for
more information.
Does it do central heating?
No, solar water heating systems will only heat your domestic hot water,
they will not heat your central heating. However it can be used for underfloor
heating, but will require supplementary heating.
I do not have a south facing roof
The tubes can be fitted to a south facing wall but the efficiency will
be less than on a sloping roof.
Does Sirena install outside The South West?
No, Sirena does not, but if you are interested, we can forward your enquiry
to a company near you that installs a similar system; however their charges
may be different.
Do you need a second cylinder?
The normal system that we use is a direct system that uses the same water
that you use to wash in to circulate via the array on the roof consequently
we do not install a second cylinder.
Does it work with Combi boilers?
No, generally Combi boilers will not accept preheated water provided by
a solar thermal system, however, if you are interested then please contact
us so we can do a specific check on your boiler's suitability.
Does it work on cloudy days?
Yes, even with cloud cover, there is still sufficient solar energy available
to heat hot water. However the heavier the clouds, the less solar energy
there is.
Does the outside temperature affect the system?
No, the Vacuum tubes act similarly to a vacuum flask so the outside temperature
has very little effect. All the pipes to and from the system are well
insulated so the heat loss is kept to a minimum.
Does it freeze?
No, the system is fully insulated. However, in the unlikely event that
the water in the roof mounted section does get close to freezing, the
controller will circulate a small amount of water from the hot water cylinder
around the system to prevent freezing from happening.
Are the tubes full of water?
The vacuum tubes consist of a double glass tube with a copper heat pipe
in it and fins that connect the heat pipe to the black sides of the glass
tube to remove the heat from the black surface and heat up the heat pipe.
This heat pipe has a small amount of water in at low pressure which means
that it boils at a low temperature causing the heat pipe to get hot. The
heat pipe is fixed into a collar in the manifold. The manifold has pipes
that carry the water from the house around these collars picking up heat
as it goes which cools the heat pipe down and the cycle starts a gain.
Consequently the tubes do not contain the water from the house the manifold
has the water flowing through it and its capacity is about 1-2 litres.
How much will I save?
For a family of four, a well designed Active Solar Heating system such
as the one provided by Sirena Environmental Ltd should contribute between
1,200kWh and 2,000kWh, which will be equivalent to 40 to 50% of the household's
water heating energy needs. The value of this saving will depend on the
type of energy displaced. (Solar trade association)
How much does it cost?
Depending on survey a typical installation will cost around £3,000
or £2,500 with the £500 grant.