Viessmann LB1 - Page 51

51
Controlled mechanical ventilation
The ventilation unit controls the fan speed so that a
consistent air flow rate is achieved for each ventilation
level. This means that the pressure drop of the duct-
work and filters does not affect the air flow rate.
The currently applicable ventilation level is either
specified via the operating status in the time program,
by the set operating program or by the selected func-
tion.
Ventilation levels
Ventilation level Function/operating program Operating status in the
"Time program, ventila-
tion"
Vitovent air flow rate
300-C 300-W
0
"Standby mode" ―
0 m
3
/h 0 m
3
/h
1
"Economy mode" ― "Background vent. C109"
Factory setting:
30 m
3
/h 50 m
3
/h
"Background vent."
"Holiday program"
2
"Automatic" "Reduced" "Reduced ventilation C10A"
Factory setting:
75 m
3
/h 100 m
3
/h
3
"Standard" "Standard ventilation C10B"
Factory setting:
100 m
3
/h 150/200 m
3
/h
4
"Intensive" "Intensive ventilation C10C"
"Intensive mode" ―
Factory setting:
125 m
3
/h 225/300 m
3
/h
Note
"Background vent." is active automatically between
the time phases in the time program.
Operating instructions "Ventilation programming
unit, type LB1"
"Intensive mode" is limited to "Duration, intensive
mode 7D1B".
In the "Standard" and the "Reduced" operating sta-
tus, the air flow rate can automatically be adjusted
subject to the following factors:
■
Humidity:
Measurement via central humidity sensor (accesso-
ries)
■
Humidity:
Measurement via CO
2
/humidity sensor (accessories)
■
CO
2
concentration:
Measurement via CO
2
/humidity sensor (accessories)
Heat recovery and humidity control
In standard ventilation mode the outdoor air and
extract air flow through the heat exchanger. All heat
exchangers used operate according to the countercur-
rent principle. This principle allows much of the thermal
energy of the extract air to be transferred to the cool
outdoor air, without the two air flows mixing together.
If an enthalpy heat exchanger is installed in the ventila-
tion unit, a part of the humidity is also transferred to
the supply air stream in addition to the thermal energy.
This contributes to a healthy ambience.
During heat recovery and humidity control the bypass
is not active.
For passive cooling the bypass is switched on: See
chapter "Passive cooling".
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:
Function description
Mechanical ventilation with Vitovent 300-C/300-W
5816558
Functions