48
The bypass is active in the following cases:
■
Passive cooling is switched on: See chapter "Pas-
sive cooling".
■
Passive heating is switched on: See chapter "Pas-
sive heating".
■
The heat exchanger is defrosted with a function that
allows the cool outdoor air to be routed past the heat
exchanger by means of the bypass: See chapter
"Frost protection".
Balancing of the supply air and extract air flow
rates
Due to the conditions in the building, an unwanted flow
rate differential (imbalance) may occur between the
supply air and extract air side, e.g. through different
lengths of ductwork for outdoor/supply air and extract/
exhaust air.
Note
To determine the flow rate differential, the captured
flow rates of all supply air apertures must be added
together and compared to the total flow rates of all
extract air apertures.
Ventilation unit installation and service instruc-
tions
Flow rate differentials > 10 % must be balanced out as
follows:
To balance out the flow rate differentials, the control
voltages of the supply and/or exhaust air fan can be
permanently increased or reduced ("Control voltage
matching, supply air fan 7D71" and "Control volt-
age matching, exhaust air fan 7D72").
Passive heating
With passive heating, the ventilation unit uses the out-
door air for central heating.
For this, the outdoor air is not routed via the heat
exchanger, but instead via the bypass directly into the
rooms.
Note
Subject to the temperature conditions, only low heating
outputs are available.
Conditions for passive heating
Passive heating ON Passive heating OFF
All of the following conditions must be met: One of the following conditions must be met:
■
Outdoor air temperature (heat exchanger air intake) is
≥ extract air temperature plus 4 K
■
Extract air temperature ≤ "Set extract air tempera-
ture 7D08" minus 1 K
■
Outdoor air temperature (heat exchanger air intake) is
≤ extract air temperature plus 3 K
■
Extract air temperature ≥ "Set extract air tempera-
ture 7D08"
Passive heating will not start if one of the following
conditions applies (bypass not active):
■
A sensor or fan fault has occurred.
■
Frost protection is active.
■
The electric preheating coil has been on in the last
10 min.
Passive cooling
With passive cooling, the ventilation unit uses the out-
door air for central cooling.
Note
Subject to the temperature conditions, only low cooling
capacities are available during passive cooling.
With passive cooling, the outdoor air is not routed via
the heat exchanger, but instead via the bypass directly
into the rooms. The bypass opens and closes automat-
ically, depending on the following conditions:
Function description
Mechanical ventilation with Vitovent 200-C (cont.)
5816558
Functions
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