Caltech Calaer 2 kW, Installation Manual

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11. Heating air system
32
11.1 Planning
The air system can be built up in two types of heating circuits Fresh-Air type
heating and Recirculation type heating.
In case of the Fresh-Air type circuit the heating air is extracted from the
outside. For this circuit type, ventilation holes to the outside are required in
every heated room to prevent pressurization of the cabin. This may result in
reduced air flow and overheating of the unit. The advantage with this type
of circuit is that fresh air is continuously introduced to the cabin. The
disadvantage is that if the target temperature is reached the heater will turn
itself off and until the temperature in the cabin drops it may blow in cold
outside air.
In the second Recirculation type of installation the heating air is extracted
from the heated cabin. When using this type of heating circuit make sure
that the air intake vent is located in an area that will not be blocked by
luggage, furniture, opening doors etc. The biggest advantages of this type of
installation is that it enables a much faster heating up time, better fuel
efficiency and more accurate temperature control of the room.
Note that regardless of the type of heating circuit used there are
limitations to the installation:

The air intake duct shall be positioned so that water or any other
foreign objects and substances cannot reach the heater.

Keep the ducting lines and bends to minimum in order to prevent high
flow resistance (risk of overheating the unit).

The air ducts should be installed so that the lines cannot be crushed or
pinched at any location.