2.2. Heat recovery
Before the stale air is discharged outside, it is filtered and
passes through the heat exchanger. The fresh outside air
is also filtered and passes through the heat exchanger
before entering the dwelling. In the heat exchanger, the
two air streams pass alongside each other but are not
mixed together. This allows heat from the exhaust air to
be transferred to the fresh supply air, so this energy is not
lost.
This heat recovery process is very efficient. On average,
around 90% of the extracted heat is returned to the
dwelling. This means that only around 10% of the heat is
lost.
Note
Despite the heat exchange process whereby Supply
air from outside is pre-heated, the balanced
ventilation system may not be regarded as a heating
system. It is a ventilation system that contributes to a
comfortable and healthy living environment in a
dwelling.
2.3. Filters
The HRU ECO 4 has two filters, one for each air stream.
Both filters are positioned in the ventilation unit so that
they protect the exchanger against soiling. In addition,
the filter in the air supply channel protects the user
against dust and other impurities found in the air drawn
in from outside.
There are various types of filters:
●
G3 filter.
This filter is supplied with the appliance as standard
and it is very suitable as a 'construction dust filter' in
the initial period following completion of the new
housing. After around three months, the filter should
be replaced with a G4 or F7 filter.
●
G4 filter.
This coarse filter is mainly used to filter relatively
large dust particles from the air. This protects the
heat exchanger in particular against incoming dirt.
●
F7 filter.
This fine filter stops fine dust particles as well as
coarser dust particles (fine dust, pollen). This is
particularly beneficial for people with allergies who
are sensitive to this.
During the product's lifetime the filters will become dirty,
which reduces the capacity of the ventilation unit. It is
therefore essential that the filters are cleaned as
indicated and ultimately replaced.
ä
Warning!
HRU ECO 4 should always be fitted with the
appropriate filters. Without filters, the appliance can
be irreparably damaged.
2.4. Controls
The HRU ECO 4 is normally equipped with a three-level
control which allows the flow rates at low speed and high
speed to be adjusted as desired with potentiometers on
the unit. In addition, the ventilation unit has some
automatic controls that operate continuously in the
background.
2.4.1. Summer bypass control
The aim of the summer bypass control is the ventilation
of the dwelling with less heat transfer or none
whatsoever.
The Heatrae Sadia HRU ECO 4 heat recovery unit is
supplied as standard with a bypass valve which is fully
integrated into the unit. This valve operates fully
automatically. The bypass allows the outdoor air intake to
go around the heat exchanger. The exhaust air always
passes through the heat exchanger.
This automatic control will primarily be activated at night
in the summer. The outside air is usually cooler than the
warm inside air at this time.
Note
The summer bypass control is not a cooling device,
but it does ensure that the dwelling remains cool for
longer on summer nights.
2.4.2. Frost protection
The HRU ECO 4 is equipped with frost protection as
standard. The frost protection consists of a unique frost
valve integrated into the top of the unit, as well as other
components. This valve operates fully automatically and
prevents freezing inside the ventilation unit during winter
weather.
The air extracted from the dwelling (exhaust air) transfers
heat to the outside air sucked in by the unit. This cools
the exhaust air in the heat exchanger. If the temperature
of the exhaust air in the heat exchanger comes too close
to the freezing point, the appliance will open the frost
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