Vallox A3741, Manual

Page: 18 / 24

18
TECHNIC
AL SPECIFIC
ATIONS
Always follow first and foremost the connection diagram
provided by the HVAC designer or heat pump manufacturer.
Also read the duct radiator manual.
The accompanying figure shows an example of the
arrangement for connecting the heating/cooling radiator unit
to the heat collection circuit.
Connect the radiator output pipe to the heat collection circuit
return pipe. Direct the fluid returning from the radiator unit to
the heat collection circuit return pipe. If you know that there
is a large loss of internal pressure inside the heat pump, the
heat pump should be bypassed. If this is done, the fluid circuit
will come into operation when the heat pump comes to a halt.
When this happens the pressure loss in the one-way bypass
valve Y2 must be lower than the pressure loss in the heat
pump.
Heating: The pump starts when the outdoor air temperature
drops below the winter limit value set at the factory (-5 °C).
Cooling The supply air setpoint value for the active mode
(for example, At home) controls the pump start-up. The pump
starts when the supply air setting is below the temperature of
the supply air that is blown into the apartment.
The duct radiator can be installed in both the supply air
duct and the outdoor air duct. If the radiator is installed in
the outdoor air duct, it can be used for both preheating and
cooling, or for preheating or cooling alone. If the radiator
is installed in the supply air duct, it can be used only for
preheating or cooling.
The duct radiator can be set to function either automatically
or manually.
• Automatic - In summer, the supply air temperature will
be maintained at the level specified in the temperature
setting. In winter, the duct radiator will turn on, when the
outdoor temperature falls below the winter setting.
• Manual - In summer, the duct radiator will turn on, when
the outdoor temperature rises above the summer setting.
In winter, the duct radiator will turn on, when the outdoor
temperature falls below the winter setting.
To prevent the risk of condensation in the supply air duct, you
can set the adjustment of the supply air limit to automatic or
manual.
• Automatic - The supply air limit is adjusted automatically
based on the dew point of the extract air. When the supply
air temperature falls too low, the duct radiator will turn off.
• Manual - The supply air limit can be set manually. When
the supply air temperature falls down to the set value, the
duct radiator will turn off.
If an external sensor is in use, it is selected from the settings
of the external sensor whether it is used to control the outdoor
air duct radiator or the supply air duct radiator.
NOTE:
If the duct
radiator is used in
the supply air duct, it
can only be used for
cooling.
NOTE:
When used to
control the outdoor air
duct radiator, the exter-
nal NTC sensor is ins-
talled in the outdoor air
duct before the radiator.
When used to control
the supply air duct ra-
diator, the external NTC
sensor is installed after
the radiator.
NOTE:
When selecting the
relay (C), take account
of the maximum
allowed combined
power supply (6W) of
the circuit board in the
external MV electrical
box, if the relay power
supply comes from the
circuit board’s +24V
connector.
NOTE:
Due to the risk of humi-
dity damage, in a duct
that has not been insu-
lated for condensation
the supply air tempera-
ture must not fall below
+16 … 20 °C.
DUCT RADIATOR OPERATION