OPERATING AND INSTALLATION MANUAL HEAT PUMP COMBI UNIT PKOM4 PAGE 33
USER
GENERALSPECIALIST PERSONNEL
14.2.2 Geothermal heat exchanger Very ecient frost protection can be
achieved by integrating a geothermal heat
exchanger into the ventilation system.
The following information must be
observed for execution of a geothermal
heat exchanger:
• The heat exchanger is laid in the ground
with waterproof pipes at a frost-free
depth with due consideration of the sys-
tem's cleanability options.
• The manufacturer's guidelines for imple-
mentation must be observed.
• Condensate drainage must be provided.
• If the air pipe is routed through an exter-
nal wall, eective sealing against mois-
ture ingress must be ensured.
• To avoid frost damage, lay to ensure ade-
quate spacing from other structural com-
ponents such as water pipes, founda-
tions, etc.
• Do not use geothermal heat exchangers if
the soil is contaminated.
• To ensure energy eciency and air
hygiene, geothermal heat exchangers
must be carefully planned and imple-
mented.
There is a risk of the heat ex-
changer freezing on the exhaust
air side, particularly during winter months
with moderate to severe frost, depending
on the extract air temperature and air
humidity. Appropriate measures must be
taken to protect the heat exchanger against
ice formation at low outdoor air tempera-
tures.
Various systems are available to monitor
defrosting of the heat exchanger. Possible
strategies to protect the heat exchanger
against freezing are outlined below.
14.2
FROST PROTECTION OPTIONS
14.2.1 Hot gas pre-heating battery The standard configuration of heat pump
combi units is with a hot gas pre-heat-
ing battery positioned in the counterflow
heat exchanger directly at the fresh air
inlet. A temperature sensor between the
hot gas pre-heating battery and the coun-
terflow heat exchanger monitors the tem-
perature of the fresh air that flows in. If
this temperature is lower than the defined
minimum temperature, the fresh air will
be pre-heated by routing hot gas from
heat exchanger circulation HK through the
pre-heating battery.
Pre-heating fresh air via the heat
pump will reduce the available
supply air heating capacity. The shortfall in
heating energy must be provided through
external means.
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