Heatrae Sadia ADVANCE Installer Manual page 12

2.7.2. Bypass control
Solely the Advance Plus is equipped with a bypass valve in the
exhaust air line. This makes it possible to control what happens to
the (warm) exhaust air from the dwelling.
When the valve is in the normal position (closed), the exhaust air
from the dwelling passes through the heat exchanger and
exchanges heat with the cold supply air from outside.
If the valve is opened, the exhaust air no longer passes through the
heat exchanger, so there is no heat exchange. Although the outside
air still passes through the exchanger, the supplied outside air is
not warmed. This is desirable when it is warmer inside than outside
in the summer.
If in the summer it is cooler inside than outside, it is desirable to
cool the incoming air ("cold recovery"). In this case, the valve is
closed so that the relatively cool indoor air again passes through
the exchanger.
The position of the bypass valve is automatically determined using
the measured outdoor temperature and the measured exhaust air
temperature.
2.7.3. Frost control
The Advance and Advance Plus have an automatic control which
protects the heat exchanger against freezing. If the measured
outside air temperature is lower than -1°C, the fan is gradually
slowed down and eventually brought to a standstill. In this case, the
unit will still respond to the timer (see "Operation"). The ventilation
unit also checks whether the temperature has risen sufficiently for
the fan to be switched back on.
Note
If the ventilation unit must continue running when the outside
temperature is lower than -1°C in order to ensure sufficient
ventilation, Heatrae Sadia advises using an external heater in the
supply duct for outside air. The temperature setpoint for this
must be -1°C.
2.7.4. Dirty filter control
The control of the Advance and Advance Plus uses a smart counter
to keep track of when the filters need to be cleaned or replaced.
This counter takes into account air quality, the service life of the
filter and the fan speed. If the system detects that a filter is dirty,
the ventilation unit sends a wireless message to this effect. This
message can be displayed on specific paired devices, such as the
RFT-L or the RF-VI (ventilation interface).
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