Technical data
www.dimplex.de 01.2012 | Project planning manual for heat pumps for heating and domestic hot water preparation | 23
Air-to-water heat pumps 2.3.4
2.3.2 Air intake or air outlet via light wells
If the wall openings for the intake or outlet air ducts are below
ground level, we recommend routing of the air circuit through
streamlining plastic light wells. An air deflector must be installed
if the wells are made of concrete. The light well on the air outlet
side should be equipped with sound-absorbing cladding.
Weather-resistant mineral fibre sheets with a volume weight of
approx 70 kg/m³ or open-cell foam, e.g. melamine foam, are suit-
able for this purpose.
Minimum dimensions for the wells: 1,000 x 400 to
1,000 x 650 mm
The transition between the light well and the wall opening
(see Chapt. 2.3.4 on page 23) should be sealed
Cover with grating (guard against burglary)
An outlet for condensate must be provided
A wire grating (> 0.8 cm mesh size) should be fitted to pre-
vent small animals from entering and leaves from falling in.
NOTE
Refer to the device information for the minimum dimensions for the air
ducting.
Fig. 2.9: Minimum light well dimensions
2.3.3 Heat pump rain guard
Rain guards act as a visual covering for wall openings above
ground and also protect the air ducts from the effects of the
weather. It is fixed to the wall from the outside and can be used
with any type of air circuit. The rain guard (special accessory)
has been specially developed for heat pumps and features a sig-
nificantly lower pressure drop than standard rain guards. It can
be used either on the air intake or the air outlet side.
A wire grating should be fitted between the wall and the rain
guard to prevent small animals from entering and leaves from
falling in. At least 80% of the grating’s cross section must be
open (mesh size > 0.8 cm). Measures to safeguard the rain
guard against burglary are to take place on site.
Table 2.4: Fixing material for rain guard
Fig. 2.10: Heat pump rain guard
2.3.4 Insulation of wall openings
Necessary wall openings should be provided on site. It is essen-
tial that the interior side of the wall opening is lined with thermal
insulation to prevent the wall from becoming cold and to prevent
moisture from penetrating the wall. For example, Fig. 2.11 on
page 23 illustrates insulation using rigid polyurethane foam
(25 mm insulation thickness). The transition between the wall in-
sulation and the wall-mounted junction box must be sealed air-
tight. Water which has penetrated due to adverse weather condi-
tions (e.g. driving rain) should be routed outside by means of a
downward slope.
NOTE
To prevent moisture from penetrating the wall and the resulting formation
of mould, the air circuit must be thermally insulated all the way to the
outer edge of the building envelope.
Fig. 2.11: Example of how to construct the wall opening
Item Designation 500-700 800 900 1,500
1 Rain guard 1 items 1 items 1 items 1 items
2 Dowel 6 x 30 4 items 6 items 8 items 14 items
3 Screw 5 x 70 4 items 6 items 8 items 14 items
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