OPERATING AND INSTALLATION INSTRUCTIONS LG 250 A
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Attention!:
This operating
mode is not suitable for frost
protection in passive houses!
The LG 250 A compact ventilation unit
range is equipped with automatic heat
exchanger frost protection as standard.
Frost protection is provided by a
continuous reduction in the supply air
flow volume with simultaneous constant
extract air flow volume. This measures
prevents the condensate generated from
freezing in the heat exchanger.
This operating mode does not
guarantee balanced air flow
volume between supply air and
extract air during defrosting!
Frost protection thanks to extract air
defrosting
• The defrosting strategy is only enabled
starting from an outdoor air intake
temperature below -4 °C.
• Where the exhaust air temperature
undercuts the "Defrost-In" setting, the
defrost function is started and the
supply air fan is then switched off. After
the defrost period has elapsed, the
rotational speed on the supply air fan is
increased continuously.
• The difference in temperature between
extract air and supply air is also
monitored. The defrost process is
activated when the "Defrost Differential"
parameter setting is exceeded.
Frost protection through reduction of sup-
ply air flow volume
The LG 250 A ventilation unit can be
supplied with a built-in (not passive
house-certified) or external electrical
PTC pre-heater battery as optional. If an
optional pre-heater battery is connected,
cold outdoor air is pre-heated via the
integrated electrical PTC low temperature
battery.
This operating mode provides
guaranteed balanced air flow
volume between supply air and
extract air during defrosting!
Frost protection thanks to stepless
preheater battery control:
• At outdoor air aspiration temperature
below -4°C, the preheater battery is
activated.
• The stepless control and adjustment
of the preheater battery maintains
the temperature upstream of the heat
exchanger at -1°C and hence prevents
the heat exchanger from freezing up.
• If the outdoor air aspiration temperature
exceeds -3°C, the preheater battery
switches off again.
• Where the ventilation unit with
integrated preheater battery is switched
off manually, the fans will continue to
run for approx. 3 minutes to cool the
preheater batteries.
PTC low temperature preheating
battery (factory setting)
integrated into the air pipe system that
has a filter quality class of at least ISO
Coarse ≥60%. The brine pump is activated
automatically, depending on the outdoor
air temperature.
Support for a brine geothermal heating
system must be activated in the
ventilation unit. PC software is used for
this purpose. Further information on
PC software is available from certified
partners upon request.
Brine geothermal heat - winter mode
If the outdoor air temperature (optional
T5 sensor required) falls below the
geothermal heat exchanger's winter
parameter, the K1 relay switches on the
brine pump.
Brine geothermal heat - summer mode
If the outdoor air temperature (optional T5
sensor required) exceeds the geothermal
heat exchanger's summer parameter, the
K1 relay switches on the brine pump.
