4.5 Option pcb
(MRXBOX90-OB)
The MRXBOX90L appliance can be equipped with an option pcb.
It provides the following functions.
Input 0-10 V for a carbon dioxide sensor
When several people are present in the dwelling, more C02 is produced
and then this sensor automatically increases the ventilation quantity.
Input 0-10 V for a moisture sensor
When the moisture content in the dwelling increases, for instance
when someone is taking a shower, this sensor automatically increases
the ventilation quantity.
Switching input for bedroom valve
With this input (make contact) the bedroom valve can be controlled,
for instance using a time switch.
Switching output for bedroom valve 24 VAC
The option pcb has a built-in control for a 24 VAC bedroom valve.
The valve can be connected directly to the pcb. The valve can be
controlled from the switching input for the bedroom valve.
Switching output for 24 VAC flue gas safety valve
If it is recommended to combine the discharge of the central heating
and the MRXBOX90L unit. The MRXBOX90L unit connection to the
joint discharge must be protected with a flue gas safety valve.
The valve can directly be connected to this pcb.
Control for pre-heater up to 1000 W
(MRXBOX90-PRE-HEATER)
The pre-heater ensures that the input air is kept above 0°C, so the
MRXBOX90L unit can continue the balanced ventilation also at very
low atmospheric temperatures. The option pcb contains a control for
a preheater up to 1000 W. The pre-heater can be connected to the
option pcb without separate control. The hook-up wire of the pre-
heater must be fed into the appliance; the 230V power cable must
separately be connected to the option pcb.
Control for post-heater up to 1000 W
(MRXBOX90-POST-HEATER)
The post-heater ensures that the supply air that is blown into the
dwelling can be kept at the preset temperature. That way additional
warmth can be brought into the dwelling. The option pcb contains a
control for a pre-heater up to 1000 W. The pre-heater can be connected
to the option pcb without separate control. The hook-up wire of the
pre-heater must be fed into the appliance; the 230V power cable must
separately be connected to the option pcb.
Two freely programmable make contact inputs
These inputs make it possible :
• to open the bypass without regard for the temperature
conditions;
• to switch the inlet or outlet low or high, to circumvent the
frost protection;
• to switch the inlet low when the bypass opens.
Switching input for emergency
For instance a fire alarm can be connected to this input. As soon as
the fire alarm is triggered, the appliance switches to emergency mode.
As standard that is set to switch off the fans.
5.0 Installation
Installation must be carried out by competent personnel in
accordance with the appropriate authority and conforming to all
statutory and governing regulations.
All mains wiring must be in accordance with the current I.E.E.
Regulations, or the appropriate standards.
Ensure that the mains supply (Voltage, Frequency and Phase)
complies with the rating label. It is recommended that the connection
to the unit is made with flexible cable.
The unit must be fitted indoors, away from any direct sources of heat,
water spray or moisture generation.
The units condensate drain must be connected to the building foul
water drainage system.
If an extract grille associated with the unit is sited in a room containing
a fuel burning unit, the installer must ensure that air replacement is
adequate for both units. Also ensure that the units external grilles are
located at least 600mm away from any flue outlet.
If the ductwork passes through an unheated loft void or similar
location, it should be insulated.
Certain applications may require the installation of sound attenuation
to achieve the sound levels required.
Unit installation procedure can be summarised
as follows:
1. Placing the unit (5.1)
2. Connecting the ducts (5.2)
3. Connecting the condensate discharge (5.3)
4. Electric wiring diagram:
connecting the multiple switch and the power supply (5.4)
MRXBOX90L units must be installed in accordance with:
• the regulations for ventilation of dwellings and residential
buildings
• the safety regulations for low-voltage installations (current
IEE regulations)
• the regulations for connection to interior sewers in dwellings
and residential buildings
• any additional regulations of the local utilities
• the installation instructions for MRXBOX90L
5.1 Placing the unit
MRXBOX90L units can be directly mounted to the wall using the
suspension strips supplied for that purpose. For a vibration-free
result the unit must be mounted to a solid wall with a minimum mass
of 200kg/m
2
. (NB. a gypsum block or metal stud wall does not
suffice. Additional measures such as double panelling or extra studs
are required).
A mounting support for floor mounting is available (article code
217031) if required. In addition, the following aspects must be taken
into account:
• the unit must be placed level
• the installation room must be such that a good condensate
dis charge with air trap and pitch for condensate can be made
• the installation room must be frost-free
• make sure there is a free space of at least 70cm at the front of
the unit and a free headroom of 1.8m for cleaning the filters
and carrying out maintenance
4
Leaflet Number 611272 January 2012
Installation and Maintenance
MRXBOX90L Mechanical Ventilation with Heat Recovery
