Vitovent 300-F: Frost Protection - Viessmann VITOTRONIC 200 Service Instructions Manual

Mechanical ventilation with Vitovent 200-C/300-F

Vitovent 300-F: Frost protection

Frost protection without preheating coil
As soon as the outdoor air temperature falls below
0 °C, the supply air fan switches off. The exhaust air
fan continues to run, causing the warm extract air to
flow through the heat exchanger, thereby preventing
ice formation on the exhaust air side. Ventilation level
is set for the exhaust air flow rate.
1
This frost protection function remains switched on for
2 h. If after these 2 h the outdoor air temperature
exceeds 0 °C, ventilation level
on for 10 min. If the outdoor air temperature continu-
ously remains above 0 °C during these 10 min, the
previously active ventilation function starts up again.
Otherwise the frost protection function is switched on
for a further 2 h.
Note
In very airtight buildings, the frost protection function
can sometimes result in the exhaust air flow rate hav-
ing to be maintained at a constant via increased
exhaust air fan speed. If during this process the max.
speed is reached for 3 min, the exhaust air fan also
switches off.
Frost protection with electric preheating coil
To avoid the frequent reduction of the supply air flow
rate or the switching off of the fans due to low outdoor
air temperatures, an electric preheating coil (accesso-
ries) can be installed. This preheating coil is electrically
connected to the controller PCB of the ventilation unit.
The preheating coil starts if the exhaust air tempera-
ture falls below the set value. The heating output is
controlled subject to either the exhaust air or the out-
door air temperature, depending on which temperature
is furthest below the relevant set value.
Vitovent 300-F: Supply air heating
With the installation of the hydraulic reheating coil
(accessories), Vitovent 300-F can be used for supply
air heating.
The reheating coil of the Vitovent 300-F is connected
hydraulically as heating circuit A1/HC1 (ventilation
heating circuit). If there is no buffer cylinder in the
heating system, the heating water buffer cylinder avail-
able as an accessory (25 l) must be installed in the
Vitovent 300-F. This heating water buffer cylinder sup-
plies the Vitovent 300-F with heat and makes the nec-
essary defrosting energy available to the heat pump.
is initially switched
1
(cont.)
Set values:
Exhaust air temperature: 3.5 °C
■
■ Outdoor air temperature: 2 °C
If the preheating coil operates for 10 min with a heating
output of 100 %, the ventilation level is also reduced
under the following conditions, if required until the fans
are switched off:
■ Exhaust air temperature < 4.5 °C
or
■ Outdoor air temperature < 3 °C
Note
If the ventilation level has been reduced for frost pro-
tection, control of the CO
2
will not be active: See page 64.
If the electrical output of the preheating coil falls below
85 % for 10 min, the ventilation level is gradually
increased until the specified stage has been reached.
Enable required
Parameter
"Enable preheater bank
electric 7D01"
Note
The electric preheating coil cannot be used for central
heating (supply air heating).
Note
If only the ventilation heating circuit A1/HC1 is connec-
ted to the heat pump (e.g. in a passive house),
observe the following:
■ The heating output of the heat pump must corre-
spond to the max. output of the reheating coil. Other-
wise use a buffer cylinder with a large volume.
■ Supply air heating can only be used as the sole heat
source in buildings with a high insulation standard,
e.g. in passive houses.
No supply air heating occurs in "Standby mode".
■
Function description
concentration and humidity
Setting
"1"
63