9
R E G U L A T E T H E T E M P E R A T U R E
The air temperature can be regulated either for con-
stant supply air temperature, constant room temper-
ature or constant exhtract air temperature.
For constant room temperature a sensor should be
placed in the room for room regulation (this is also
suitable when a cooling coil is incorporated in the
system).
Extract air regulation functions in a similar way
but with the difference being that the sensor is
placed at the extract air of the unit.
The temperature can be regulated in 5 sequences:
1.Cooling re After cooling:
The regulation
unit can regulate a cooling coil (e.g. cooling water
from bedrock), when the cooling recovery from
the rotor is not enough.
2.Cooling recovery or regulated after cooling:
The
rotary heat exchanger starts if the extract air tem-
perature is lower than outside temperatur.
Regulated after cooling: The aftercooling starts
when the outside temperature is lower than de-
sired room temperature and is not enough to lower
the room temperature.
3.Outside temperature = desired temperature:
When
the outside temperature is the same as desired sup-
ply air temperature the rotor stops.
4.Heat recovery:
The rotary heat exchanger starts to
recover the warmer room temperature.
5.Heat re heat:
In climate conditions where
the rotary heat exchanger, in spite of its high effi-
ciency, is not sufficient to reach the desired supply
air temperature, the controller can regulate either
the built-in electric duct heater or a heating coil.
F A N C A P A C I T Y
Airflow (fan speed) is regulated via the week timer
that can be programmed for specific time points
when the fan speed should change from one speed to
antoher (e.g. home or away setting). A special feature
is that you can pressure compensate when supple-
mentary heating, using an open fire or stove (the
extract air fan then drops to a lower speed).
With the weektimer function it is possible to
schedule different fan speeds e.g away/boost or
standby. The fan speed can also be controlled by a
carbon dioxide (CO
2
) and humidity (RH) sensor so
that the unit gives a higher airflow (boost) when the
maximum limit value has been exceeded.
”Summer Cooling”
is a function where you can use
the cool outside temperature to cool down the inside
air. The fan speed is boosted when the ratio between
the outside temperature and the extract air temper-
ature is within the programmed criteria.
Via the wireless control unit the HERU can be put in
an ”Off mode”, which means that the motors for fans
and rotor are ”Off” but the unit is ”Stand by”. If there
is a requirement of totally cut off power, a discon-
nect switch must be mounted on the main electrical
feed.
Boosting the airflow for a specified time can be done
via the wireless control, there is also a opportunity to
do that via a timer connected to the ”0” and ”Boost”
connection on the PCB. With the connectors closed
the boost function will be ”On”.
R E G U L A T I O N F U N C T I O N S
3.
Outside temperature = Desired temperature
1.
Cooling recovery
+
After cooling
2.
Cooling recovery
or After cooling
4.
Heat recovery
5.
Heat recovery
+
After heat
Regulated
after cooling
0-100%
Regulated
after heating
0-100%
Rotor 100%
Regulated rotor
0-100%
Rotor 100%
Regulated rotor
0-100%
