19.1 Subsidy programs, permits and insurance
Solar thermal systems play an important role in protecting natural
resources and the environment. Together with advanced Viessmann
heating systems, they create an optimum system solution that is fit for
the future for DHW and swimming pool heating, central heating backup
and other low temperature applications. This is why solar thermal sys-
tems are frequently subsidised by government.
Application forms and subsidy conditions can be obtained from the
Federal Office of Economics and Export Control (www.bafa.de). Solar
thermal systems are subsidised by some national, regional and local
authorities. Further information is available from our sales offices.
Information regarding current subsidy programs [Germany] is also
available at "
www.viessmann.com
" (Fördermittel [subsidy pro-
grammes]>Förderprogramme des Bundes [subsidy programmes in
Germany]).
Viessmann collectors meet the requirements of the "Blue Angel" cer-
tificate of environmental excellence to RAL UZ 73. The approval of
solar thermal systems is not universally regulated. Your local planning
office will be able to advise you on whether solar thermal systems need
planning permission.
Viessmann solar collectors are tested for impact resistance, for exam-
ple against hailstones, to DIN EN 12975-2. Nevertheless we recom-
mend that the user insures against extreme weather conditions and
includes the collectors on their buildings insurance. Damage due to
these conditions is excluded from our warranty.
19.2 Glossary
Absorber
Device contained inside a solar collector designed to absorb radiation
energy and transfer this as heat to a liquid.
Absorption
Radiation absorption
Irradiance (insolation)
Radiation level impacting on a unit of surface area, expressed in W/
m
2
.
Emission
Radiation of beams, e.g. light or particles
Evacuating
Extraction of the air from a container. This reduces the air pressure,
thereby creating a vacuum.
Steam production capacity
The output of the collector array in W/m
2
that, during stagnation, is
transferred into the pipework in the form of steam. The max. steam
production capacity is influenced by the draining characteristics of the
collectors and the collector array (see page 152).
Steam spread
Length of the pipework that is subjected to steam loads during stag-
nation. The max. steam spread is dependent on the heat loss charac-
teristics of the pipework (thermal insulation). Conventional details refer
to 100 % insulation strength.
Heat pipe
Sealed capillary container that contains a small volume of highly vol-
atile liquid.
Condenser
Device where steam is precipitated as a liquid.
Convection
Transfer of heat by the flow of a medium. Convection creates energy
losses caused by a temperature differential, e.g. between the glass
pane of the collector and the hot absorber.
Standard roof pitch
The roof pitch limit, at which the roof cover is considered to be ade-
quately protected against the ingress of rain, is described as standard
roof pitch.
The rules stated here correspond to the rules of the [German] roofing
contractor trade. Observe alternative manufacturer's details.
Selectively coated surface
The absorber in the solar collector is highly selectively coated to
improve its efficiency. This specially applied coating enables the
absorption to be maintained at a very high level for the sunlight spec-
trum that hits the absorber (approx. 94 %). The emission of long-wave
heat radiation is largely prevented. The highly selective black chro-
mium coating is very durable.
Radiation energy
Volume of energy transmitted by radiation.
Dispersion
Interaction of radiation with matter by which the direction of the radia-
tion is altered; total energy and wavelength remain unchanged.
Vacuum
A space devoid of air.
Heat transfer medium
Liquid that absorbs the available heat in the absorber of the collector
and delivers it to a consumer (heat exchanger).
Efficiency
The operating efficiency of a solar collector is the ratio of the collector
output to the power input. Relevant variables are, e.g., the ambient
and absorber temperatures.
Appendix
VITOSOL
VIESMANN
157
5822 440 GB
19
