Insulation of ducts in heated rooms
Genvex recommends the following:
Supply and extract ducts
In a warm attic, the supply and extract ducts must be provi-
ded with 50 mm of insulation finished with
aluminium foil.
Supply and extract ducts routed through heated rooms in
the home need not be insulated unless
cooling, bypass or geothermal heat exchangers are used. In
such cases, the supply duct must be insulated.
Fresh air and discharge ducts
In warm attics and heated rooms in the home, fresh air and
discharge ducts must be provided with a minimum of 50
mm of insulation. In addition, the insulation must be lined
on the outside with plastic or aluminium foil to prevent con-
densation in the insulation.
Contact your local supplier for advice on national guide-
lines on insulation.
When using a geothermal heat exchanger, it is recommen-
ded adding 100 mm of insulation to the fresh air duct.
Post-heating of the supply air
Since the countercurrent heat exchanger cannot recover all
the heat from the extract air to the supply air, in the winter
season the supply air will be approx. 1–4°C lower than the
room temperature in the home. If it is desired to use the
system for heating, a water or electric heating surface able
to heatthe supply air to room temperature can be installed.
Water post-heating surface
To protect the water post-heating surface against frost
burst, a water frost sensor must be installed on the water
post-heating surface and the water post-heating surface
must be insulated. The water frost sensor is installed on the
back of the slats of the water post-heating surface. The
sensor for controlling the motor valve is installed in the
supply duct approx. 500 mm after the water post-heating
surface so that it is not affected by radiant heat from the
heater. The water connection to the water post-heating
surface must be executed by an authorised plumber.
Electric post-heating surface
The sensor for controlling the electric heating surface is
installed in the supply duct approx. 500 mm after the
electric heating surface so that it is not affected by radiant
heat from the heater.
Electric preheater
At outdoor temperatures below 0°C, it is recommended
installing an electric preheater to prevent ice accumulation
in the countercurrent heat exchanger. The sensor for
controlling the electric preheater must be installed in the
fresh air duct 500 mm before the electric preheater (in the
case of an on/off preheating surface).
Note – when a modulating preheating surface with a solid
state relay is used, the existing fresh air temperature
sensor in the ventilation unit can be used to control the
preheater (no additional temperature sensor is required).
With a factory-fitted, integrated preheating surface, it is
recommended using the built-in discharge temperature
sensor as a reference sensor (see Optima 270 operating
instructions for configuration).
Capacity
The diagram shows the temperature increase of the air for different air volumes after it has passed through the heating
surface. To ensure as low an energy consumption as possible, the lowest possible power must be selected (this primarily
applies to the on/off heating surface).
Temperature increase °C
Air volume m
3
/h
0
20
40
60
80
100
120
50
100
150
200
250
300
350
400
450
300 watt
600 watt
900 watt
1200 watt
1500 watt
1800 watt
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