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Note
Despite the heat exchange, in which the fresh outside air is pre-
heated, the balanced ventilation system should not be regarded
as a heating system. It is a ventilation system that contributes to
a comfortable and healthy living environment in the home.
2.8. Schemes
The HRU ECO 350 has as standard a 3-position control where the
ventilation flow in the low position and the high position can be
infinitely adjusted by means of potentiometers on the unit. In
addition, the ventilation unit has a number of automatic controls that
operate continuously in the background.
2.8.1. Heat recovery
Before the polluted air is removed to the outside, it is filtered and
passed through the heat exchanger. The fresh outside air is also
filtered and passed through the heat exchanger before it is brought
into the house. In the supply air, so that this energy is not lost.
Heat recovery takes place with a very high efficiency.
2.8.2. Summer bypass scheme
The purpose of the summer bypass control is to ventilate the house
with less, or completely without, heat transfer.
The Itho Daalderop heat recovery unit HRU ECO 350 is supplied
as standard with a bypass valve that is 100% integrated in the
unit. This valve works fully automatic. The bypass ensures that
the sucked in outside air is guided around the exchanger. The
return air still passes through the exchanger.
This automatic control will be activated mainly at night, in summer.
The outside air is then usually cooler than the warm inside air.
2.8.3. Vorstregeling
The purpose of the frost control is to prevent the heat exchanger
from freezing and to prevent ventilation.
If the temperature of the supply air in the heat exchanger gets too
close to freezing point, the unit will regularly open the frost flap at
the top of the unit and draw in warm room air. This warm room air
is mixed with the drawn in cold outside air. At the same time, the
supply fan starts to turn harder (the fan is speeded up so that the
amount of fresh outside air remains the same). Because the fresh
cold outside air is pre-heated, the warm extracted air from the
house does not have to heat the cold freezing air as much. The
automatic control keeps the temperature of the supply air in the
heat exchanger safely above freezing point.
Should the outside temperature drop even further, the supply fan
will turn softer (the fan will be turned down to a minimum).
If the temperature continues to drop, the drain fan will increase and
the supply fan will continue to run at a minimum.
If the outside temperature becomes extremely low, the supply fan
will be switched off, but the exhaust fan will continue to operate.
The frost valve will therefore be closed.
After a certain period of time, the supply fan will start to run at a
minimum and the frost valve will be opened again to check whether
the frost hazard is now gone.
If the outside temperature rises, the above measures are carried
out in reverse order until the danger of frost has passed. The
resident 'always' determines the discharge air quantity.
Note
The summer bypass control is not cooling, but it does ensure
that the house remains cool longer in the summer night.
