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Ensure that the comfort temperature
in winter is not set below the tem-
perature you prefer.
2. Instructions for the User
This chapter describes how you should use the MTD-ERV 350.
Instructions for the User 3
2
Congratulations, you are now the owner of
the MTD-ERV 350,
the heat recovery unit from Zehnder Com-
fosystems. We wish you every comfort.
2.1 Defi nition of Terms
The MTD-ERV 350 has the following functions:
• Balanced ventilation.
• Heat recovery.
• Bypass for free cooling.
• Frost protection.
• Chimney sweep control.
• Moisture recovery (option).
These terms/properties are described in more detail
briefl y in the following sections.
2.1.1 Balanced Ventilation
The MTD-ERV 350 is a balanced ventilation sys-
tem. This is the most economical and balanced
form of ventilation for homes. In a balanced
ventilation system, polluted air from kitchen,
bathroom, toilet and possibly even store room
is drawn off and replaced by an equal volume
of fresh air in the living room and bedroom. Air
gaps under the doors ensure good air circula-
tion in the home. This air circulation is literally
balanced.
derevoc ton era spag eseht taht erusnE
by, for example, rubber door seal strips
or high-pile carpets. This would prevent
the system from operating optimally.
2.1.2 Heat Recovery
Apart from ensuring the right balance between sup-
ply and exhaust air, the MTD-ERV 350 also offers the
advantage that the heat from the exhaust air is given
off to the fresh, generally cooler outside air. This is
made possible by the integral heat exchanger. In
this way, roughly 95% of the discharged heat is re-
covered. The supply air can enter the rooms almost
at room temperature. Draughts are now a thing of
the past.
2.1.3 Bypass for Free Cooling
Apart from transferring heat from the exhaust air
to the fresh, generally cooler outside air, the MTD-
ERV 350 also offers the possibility of discharging
the warmer exhaust air directly into the atmosphere
without passing through the heat exchanger. This is
made possible by the integral bypass. The bypass is
an additional circulating air duct that (temporarily)
interrupts the heat transfer between the exhaust air
and supply air. The cool outside air is then not pre-
heated before it enters the dwelling.
The bypass is used particularly on warm days dur-
ing the summer months. Admitting the cool night
air on warm days allows the room temperature in
the home to be reduced. The bypass functions auto-
matically. You simply have to set your comfort tem-
perature. See section 2.3.2 for further information.
The MTD-ERV 350 then maintains this temperature
as closely as possible.
si retniw ni erutarepmet trofmoc eht fI
below the preferred temperature, it is
possible for the heating to be switched
on with the bypass open. That is a waste
of energy.
2.1.4 Frost Protection
The MTD-ERV 350 also has a frost protection system.
This protects the heat exchanger (or the optional
combined heat and moisture exchanger, see sec-
tion 2.1.6) from freezing. The risk of freezing exists
in the winter months with moderate to heavy frost.
The MTD-ERV 350 is equipped as standard with an
automatically activated frost protection system that
- when there is a risk of frost - temporarily
reduces the supply of outside air so that condensa-
tion in the exchanger cannot freeze. A preheater can
also be installed in the MTD-ERV 350 as an option.
This has the advantage that the balanced ventilation
then remains operational. The inlet of cold outside
air then no longer needs to be reduced. In addition,
this option offers greater comfort as the supply air is
again preheated to more or less room temperature.
If there is no preheater installed in your MTD-ERV
350, ask your installer about the possibilities.
2.1.5 Chimney Sweep Control
The MTD-ERV 350 also has a chimney sweep control
system. This is a system that prevents the MTD-ERV
350 from creating an imbalance in the ventilation
system, i.e. between the supply and exhaust air.
The chimney sweep control system functions auto-
matically. This system blocks or resets other ventila-
tion control systems that could possibly create an
imbalance in the ventilation system and that can be
automatically switched on and off by the software.
One example of this is that the supply and exhaust
air fans cannot be switched off separately when the
chimney sweep control system is active.
The chimney sweep control system is employed in
dwellings with open fi re, as here air can be drawn
back by the draught of the chimney. If problems
occur with the smoke discharge via the draught of
the chimney, this situation must on no account be
caused (or exacerbated) by the MTD-ERV 350. The
chimney sweep control system then interacts with
the existing ventilation control systems in such a
way that the MTD-ERV 350 cannot (or can no longer)
cause an imbalance in the ventilation system.