NuAire MRXBOXAB-ECO-LP2SW Instruction Manual

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nuaire.co.uk 029 2085 8400 20. 08. 19. Leaflet Number 671876
The EMC Directive
2014/30/EU
The Low Voltage
Directive
2014/35/EU
MRXBOXAB-ECO-LP2SW (Standard Unit)
MRXBOXAB-ECO-LP2OHSW (Opposite Hand Unit)
Mechanical Ventilation Unit with Heat Recovery for
Ceiling Void Mounting
Installation and Maintenance
1.0 SAFETY INFORMATION
•The provision of the electrical supply and the connection of the unit to the mains
must be carried out by a qualified electrician.
•Isolate from power supply before removing any covers. During installation /
maintenance ensure all covers are fitted before switching on the mains supply.
•All-pole disconnection from the mains as shown in the wiring diagram must be
incorporated within the fixed wiring and shall have a minimum contact separation of
3mm in accordance with latest edition of the wiring regulations.
•This unit must be earthed.
•Ducting must be securely fixed with screws to the spigot to prevent access to live
parts. Duct runs terminating close to the fan must be adequately protected by
suitable guards.
•If the supply cord is damaged, it must be replaced by the manufacturer, its service
agent or similarly qualified persons in order to avoid a hazard.
•Precautions must be taken to avoid the back-flow of gases into the room from the
open flue of gas or other fuel-burning appliances.
•This appliance should not be used by children or persons with reduced physical,
sensory or mental capabilities or lack of experience and knowledge, unless they
have been given supervision or instruction concerning the safe use of the appliance
by a person responsible for their safety. Children shall not play with the appliance.
Cleaning and user maintenance shall not be carried out by children.

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nuaire.co.uk 029 2085 8400 20. 08. 19. Leaflet Number 671876
Installation and Maintenance MRXBOXAB-ECO-LP2SW Mechanical Ventilation Unit with Heat Recovery
Spigot 3.
Spigot 2.
Spigot 1.
Spigot 4.
Figure 1. Airflow Through Unit (Standard Configuration)
Spigots 1 to 4
1. Intake Air (Fresh air from outside).
2. Supply Air (Supply in to house).
3. Extract Air (Warm stale air from house).
4. Exhaust Air (Waste air to oustide).
Spigot 1.
Spigot 4.
Spigot 3.
Spigot 2.
Figure 2. Airflow Through Unit (Opposite Handing)
Spigots 1 to 4
1. Intake Air (Fresh air from outside).
2. Supply Air (Supply in to house).
3. Extract Air (Warm stale air from house).
4. Exhaust Air (Waste air to oustide).
2.0 INTRODUCTION
The LP2 ceiling void mounted unit is designed to provide mechanical
supply and extract ventilation with heat recovery and incorporates HX
bypass.
The unit is fitted with two independent fans. Each fan has full speed
control for background and boost ventilation rates. To recover heat
from the extract air the heat exchanger block is utilised. The heat
exchanger can recover up to 80% of the normally wasted heat.
IMPORTANT
The unit must remain switched on at all times to maintain ventilation
within the dwelling. Turning the unit off will cause long term damage to
the unit and building fabric.
This appliance is not intended for use by persons (including children) with
reduced physical, sensory or mental capabilities, or lack of experience
and knowledge, unless they have been given supervision or instruction
concerning the use of the appliance by a person for their safety. Children
should be supervised so that they do not play with the appliance.
3.0 INSTALLATION
Installation must be carried out by competent personnel in accordance
with the appropriate authority and conforming to all statutory
governing regulations. Beware of sharp edges on unit when handling,
ensure appropriate PPE is used. 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.
Please note a clear working space is required around the installed unit
to allow the cover to be removed and provide sufficient access for
maintenance such as filter change.
The fan must be installed indoors, in a suitable ceiling void away from
direct sources of frost, heat, water spray or moisture generation. For a
vibration-free result the unit must be mounted to a solid surface in the
void.
The unit is designed for ceiling mounting only (Horizontal surface).
The unit is supplied with a steel mounting bracket.
Position & secure the steel bracket to the ceiling using appropriate
fixings (supplied by others), ensuring that the two outer fixing holes on
the unit are accessible (Figure 3).
Note: The mounting bracket should be on the same side as the
condensate take off.
3. The unit can now be offered into position & located into the
mounting bracket.
4. Using appropriate fixings (supplied by others) fix the unit to the
ceiling. It is recommended that the unit is fixed through three holes on
the non-bracket side and the two outer holes on the bracket side.
Note: The unit must be installed in an upright position as shown for
the condensate drain and for compliance with safety regulations
relating to IP protection for water drip ingress.
Steel mounting bracket
Figure 3. Installing Unit Using Appropriate Fixing Bolts (Standard)
IMPORTANT
Isolation - Before commencing work, make sure that the unit, switched
live and Nuaire control are electrically isolated from the mains supply and
switched live supply.

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nuaire.co.uk 029 2085 8400 20. 08. 19. Leaflet Number 671876
Installation and Maintenance MRXBOXAB-ECO-LP2SW Mechanical Ventilation Unit with Heat Recovery
ducting in
204 x 60mm
ceiling void.
in ceiling.
Side view of unit
mounted in the ceiling void.
Air valve
Figure 4. Typical Side View Example of Unit (Standard) Mounted in
Ceiling Void Using 204 x 60mm Rectangular Ducting and Air Valves
3.1 Condensate Drain Installation
1. Unit comes complete with external drain pipe (21.5mm waste pipe).
Use conventional plumbing connections to link up with U-trap,
detachable compression fit connections are recommended to allow
removal of condensate tray for maintenance of the heat exchanger.
2. This condensate discharge connection is suitable for 21.5mm
diameter overflow pipe.
3. If using a U-trap please ensure the U-trap has been filled to a
suitable level of water to avoid any air locks.
4. If the condensation pipe is fitted in an unheated space the pipe
should be in insulated to prevent freezing.
Nuaire recommend MVHR-DRAIN be used as the primary condensate
take-off (see fig. 5 and 6).
CORRECT INCORRECT
Flow
Side elevation
When installed horizontally the ribs must be at the bottom to
ensure correct operation.
Figure 5. MVHR-DRAIN Condensate Drain, Running to SVP (Standard
Unit)
Figure 6. MVHR-DRAIN Correct Installation
3.1.1 Fixing
Offer up the MVHR-DRAIN inlet to the threaded tail of the appliance
waste outlet or MVHR-DRAIN knuckle or running adaptor, and tighten
the threaded cap sufficiently hand-tight to provide a water-tight seal
(check that the cap screws on square and does not ‘cross-thread’).
When the screwed cap is tight, the MVHR-DRAIN body is secure.
1. Cut the pipe to length, allowing for the full compression socket
depth (using an appropriate pipe cutter, such as a Hepworth ratchet
pipe cutter).
2. Remove any ‘swarf’ from the end of the plastic pipe. Ream the
copper pipe end to remove any ‘burr’, and file if necessary to remove
any external sharp edges. Mark the socket depth on the pipe, and
check that the pipe section to be jointed is free of any surface
damage which may affect the joint seal.
3. Unscrew the cap from the MVHR-DRAIN outlet, and slide the cap
and rubber seal onto the pipe.
4. Insert the pipe end fully into the socket.
5. Slide the rubber seal and screwed cap up against the face of the
socket, and tighten the cap sufficiently hand-tight (check that the
cap is square to the body and does not ‘cross thread’). Hand tight
should be adequate to form a proper seal.
3.2 Extract/Input Areas
The unit is designed to extract air from all wet rooms e.g. bathroom,
kitchen, en-suite, utility room (with sink).
WC’s do not need to be ventilated if openable windows are fitted.
Supply air should be to all habitable rooms e.g. bedrooms and lounge.
Extract / input grilles should be adjustable valve types (not supplied).
External grilles must have a minimum free area of 12,250 mm2.
3.3 Ducting
Before commencing ducting installation reference should be made
to building regulations document “Domestic ventilation compliance
guide”. This document supports ADF2010 and details installation,
testing and commissioning of all ventilation systems.
It is recommended that rigid ducting must be used it all times. Flexible
ducting has a very high resistance and it is impossible to calculate
how much resistance will be on a system if used. If used the flexible
ducting must be kept to a minimum and should always be pulled taut.
A maximum of 300mm should be used on each leg.
To prevent condensation on the outside of the outside air inlet duct and
the air outlet duct from the MRXBOXAB-ECO-LP2, these ducts should
be insulated.
Ducting must be installed in such a way that resistance to airflow is
minimised. Bends should be kept to a minimum.
A minimum distance of 300mm between the appliance and any bends
in ductwork is recommended.
204 x 60mm rectangular ducting should be used (refer to dwelling
ducting design drawing, Figure 8 on page 5 for further information).
Ducting joints must be sealed with silicone type sealant and needs
to be taped. Ducting shall be adequately and reliably fixed to the
appliance with screws to prevent access to live parts.

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nuaire.co.uk 029 2085 8400 20. 08. 19. Leaflet Number 671876
Installation and Maintenance MRXBOXAB-ECO-LP2SW Mechanical Ventilation Unit with Heat Recovery
Table 1. ADF 2010 - Extract ventilation rates.
Table 2. Whole dwelling ventilation rates.
Notes:
1. In addition, the minimum ventilation rate should be no less than
0.3 l/s per m2 of internal floor area. (This includes all floors, e.g.
for a two-story building add the ground and first floor areas).
2. This is based on two occupants in the main bedroom and a single
occupant in all other bedrooms. This should be used as the default
value. If a greater level of occupancy is expected add 4 l/s per
occupant.
Room Min high rate Min low rate
Kitchen 13 l/s Total extract rate
should be at least
the whole dwelling
ventilation rate given
in table 2.
Utility Room 8 l/s
Bathroom 8 l/s
Sanitary
Accommodation 6 l/s
Number of bedrooms in dwelling
1 2 3 4 5
Whole dwelling
ventilation rate
(l/s)
1,2
13 17 21 25 29
3.4 Ventilation Flow Rates
3.5 ADF 2010 Ventilation Calculations Design of MVHR
Systems
The MVHR system has been sized for the winter period. Additional
ventilation may be required during the warmer months and it has
been assumed that the provisions for purge ventilation (e.g. openable
windows) could be used.
Step 1: For any design air permeability, determine the whole dwelling
ventilation supply rate from Table 2.
As an alternative where the design air permeability is intended to be
leakier than (>) 5m3/(h.m2) 50 Pa, allow for infiltration for all dwelling
types by subtracting from the whole dwelling ventilation supply rate
from Table 2; 0.04 x gross internal volume of the dwelling heated space
(m3).
Step 2: Calculate the whole dwelling extract ventilation rate by
summing the individual room rates for ‘minimum high rate’ from Table
1. (For sanitary accommodation only, as an alternative, the purge
ventilation provisions given in ADF 2010 can be used where security is
not an issue. In this case ‘minimum high extract rate’ for the sanitary
accommodation should be omitted from the step 2 calculation).
Step 3: The required airflow rates are as follows:
The maximum whole dwelling extract ventilation rate (e.g. boost)
should be at least the greater of step 1 and step 2.
Note that the maximum individual room extract rate should be at least
those given in table 1 for minimum high rate.
The minimum air supply rate should be at least the whole building
ventilation rate found in step 1.
For Scotland refer to BRE Digest 398.
For further information refer to the “Domestic Ventilation Compliance
Guide”.
IMPORTANT
Any air intake terminal MUST be installed in accordance with the appropri-
ate regulation.
As a guide, the BS5440 series of British Standards deals with this issue
and currently states that an air intake must be at a minimum distance of
300mm from a gas boiler balanced flue.
Installers are advised to be aware of the requirements of this standard
when installing ‘through the wall’ supply air ducting.
Pre Commissioning MRXBOXAB MVHR Units
MRXBOXAB units are designed to ventilate the whole dwelling
and must not be used during site construction or the clean-up
period. Cement and plaster dust can be abrasive and can affect
fan performance and reliability. Please ensure that the filters are
checked prior to commissioning to ensure there is no build-up of
dust or debris.
While the property is drying out, very high moisture levels are likely
to occur. Therefore it is advisable that if the installation and building
works are complete the unit is left running. If the building works are
not complete please close the air valves or cover up the air valves to
prevent condensation forming in the ductwork and the MRXBOXAB
unit due to natural migration of warm air.

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nuaire.co.uk 029 2085 8400 20. 08. 19. Leaflet Number 671876
Installation and Maintenance MRXBOXAB-ECO-LP2SW Mechanical Ventilation Unit with Heat Recovery
4.0 DIMENSIONS (mm) STANDARD CONFIGURATION
5.0 DUCTING ARRANGEMENTS, STANDARD CONFIGURATION
700
View from top (A)
668 hole centres
View from control side
900
371
857
885 hole centres
121
End view
200
67
(B)
(A)
600
Spigot 2.
View from underside with cover removed (B)
Air
Supply
Spigot 3.
Extract
Air
Spigot 4.
Air
Exhaust
Spigot 1.
Air
250
Intake
Heat
exchanger
Bypass
chamber
Supply
fan
Extract
fan
21.5mm condensate pipe
Drip tray
Wire
frame
filter
Wire
frame
filter
Bypass
4.
damper
1.
2.
3
735 (Filter access distance)
Removable
access
filter
Removable
access
filter
69
97 342
Access
Requirements
Supply air to
lounge via
in ceilings.
Air Valve
Extract air from
kitchen via
in ceilings.
Air Valve
Supply air to
bedrooms via
in ceilings.
MVHR-DRAIN
Air Valve
condensate drain,
running to SVP.
mounted unit.
Nuaire ceiling void
Extract air from
bathroom via
in ceilings.
Air Valve
Exhaust air from
kitchen/bathroom to
outside via air brick.
Supply and extract
ducts from external
air bricks to the unit
needs to be insulated.
Top of ceiling void.
Minimum distance as
specified in Building
Regulations.
Intake air from
outside via air brick.
Figure 7. Dimensions & Access Requirements (Standard)
Figure 8. Typical Ducted Arrangement for a Void Mounted Unit (Standard) Using Rectangular Ducting and Ceiling Air Valves

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nuaire.co.uk 029 2085 8400 20. 08. 19. Leaflet Number 671876
Installation and Maintenance MRXBOXAB-ECO-LP2SW Mechanical Ventilation Unit with Heat Recovery
6.0 DIMENSIONS (mm) OPPOSITE HAND CONFIGURATION
7.0 DUCTING ARRANGEMENTS, OPPOSITE HAND CONFIGURATION
688 Hole Centres
View from top (A)
700
View from control side
900
371
857
885 hole centres
121
End view
200
67
(B)
(A)
600
Spigot 2.
View from underside with cover removed (B)
Air
Supply
Spigot 3.
Extract
Air
Spigot 4.
Air
Exhaust
Spigot 1.
Air
250
Intake
Heat
exchanger
Bypass
chamber
Supply
fan Extract
fan
21.5mm condensate pipe
Drip tray
Wire
frame
filter
Wire
frame
filter
Bypass
4.
damper
1.
2.
3.
735 (Filter access distance)
Removable
access
filter
Removable
access
filter
69 97 342
Access
Requirements
Supply air to
lounge via
in ceilings.
Air Valve
Extract air from
kitchen via
in ceilings.
Air Valve
Supply air to
bedrooms via
in ceilings.
MVHR-DRAIN
Air Valve
condensate drain,
running to SVP.
mounted unit.
Nuaire ceiling void
Extract air from
bathroom via
in ceilings.
Air Valve
Exhaust air from
kitchen/bathroom to
outside via air brick.
Supply and extract
ducts from external
air bricks to the unit
needs to be insulated.
Top of ceiling void.
Minimum distance as
specified in Building
Regulations.
Intake air from
outside via air brick.
Figure 9. Dimensions & Access Requirements (Opposite Hand Unit)
Figure 10. Typical Ducted Arrangement for a Void Mounted Unit (Opposite Hand) Using Rectangular Ducting and Ceiling Air Valves

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nuaire.co.uk 029 2085 8400 20. 08. 19. Leaflet Number 671876
Installation and Maintenance MRXBOXAB-ECO-LP2SW Mechanical Ventilation Unit with Heat Recovery
EXTRA
EXTRA
CT F
CT F
AN
LIAF
Supply Extract Supply Extract Supply Extract
SPEED 1 SPEED 2 SPEED 3
3
2
8.0 ELECTRICAL CONNECTION
IMPORTANT
For good EMC engineering practice, any sensor cables or switched live
cables should not be placed within 50mm of other cables or on the same
metal cable tray as other cables.
Please note: the electrical connection of the unit
must be carried out by a qualified electrician.
The unit is supplied with a flexible cord for
connection to the mains supply.
Electrical details:-
Voltage: 240V 1ph 50Hz
Consumption: LP2 - 1.3 Amps
Fuse rating: 3 Amps
NOTE: This unit must be earthed.
The cable from the mains power supply should
be connected to a fixed wiring installation, via
a fused isolator, in accordance with current IEE
wiring regulations.
Note: for Ecosmart sensors/controls cut a slit in the
grommet and feed the Ecosmart connector through
to retain sufficient protection against water ingress.
Ensure Ecosmart cabling is secured with P-clips
supplied to provide suitable cable retention.
Note: Wiring is for reference
purposes only as the
connections above are
factory fitted.
Connection to Remote Fail
Indicator Ref: MRXBOX95-RFI
(optional).
Fuse 2A
MAINS
230V
50Hz
light
Room
Light
switch
(Double
Pole)
N
L
3 Pole
isolator
Kitchen switch
Blue
Brown
Black
Optional speed 3 switch
Supply cord
from unit
Grey
Green/yellow
Fuse 2A
MAINS
230V
50Hz
Room
lights
Light
switches
(Double
Pole)
N
L
3 Pole
isolator
Kitchen switch
Blue
Green/yellow
Brown
Black
Supply cord
from unit
Optional speed 3 switch
Grey
Unit serving kitchen and bathroom
Unit serving kitchen and two bathrooms
Figure 11. PCB Details
Figure 12.
Figure 13.
Disconnection from the supply mains
must be incorporated within the fixed
wiring in accordance with the wiring
regulations and shall have a minimum
contact separation of 3mm.
Disconnection from the supply mains
must be incorporated within the fixed
wiring in accordance with the wiring
regulations and shall have a minimum
contact separation of 3mm.
Figure 14.
Connection of summer/winter switch
Black
2 core cable
from unit
Red
Volt free Summer / Winter Switch (supplied with unit)
Polarity is inconsequential
Warning! - Do not connect to mains!
8.1 Examples of Typical Wiring Layouts

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nuaire.co.uk 029 2085 8400 20. 08. 19. Leaflet Number 671876
Installation and Maintenance MRXBOXAB-ECO-LP2SW Mechanical Ventilation Unit with Heat Recovery
1. For the required air flow rates please refer to the design specification
for the property, follow 2.4, or refer to building regulations ADF
2010.
2. The unit is supplied with independent control for both normal and
boost airflows. (see fig. 10).
3. Correct commissioning is essential to ensure the ventilation air
flowrates are met. It also ensures the unit is not over ventilating and
causing excessive power consumption.
4. Commissioning should be carried out in accordance with building
regulations document “Domestic ventilation compliance guide”.
A calibrated moving vane anemometer and hood will be required to
carry out commissioning.
5. Adjustment valves should be locked in place to prevent further
adjustment.
6. Once commissioned the home owner / tenant should be informed
that the unit should not be adjusted as it will have a detrimental
effect on the indoor air quality and could result in condensation and
mould growth. The label covering the control has an adhesive panel
which should be removed post commissioning to prevent tampering.
Control module
+ - - + - + - + - +
Power
Post commissioning remove
adhesive backing under
this section
060905
Ventilation Controls
For commissioning:
refer to user manual
+ -
9.0 COMMISSIONING
IMPORTANT
The filters fitted inside the unit are protected with a plastic film. Prior to
commissioning remove the covers (fig. 13), take off the film and replace.
Figure 15. PCB inside enclosure.
HX Bypass
(AB units only)
Speed 1
Speed 2
Speed 3
Supply Fan Fault
Extract Fan Fault
Frost Protection
Filter Change
10.0 STATUS INDICATION
The status of the unit is indicated by a series of LED’s on the control box
cover. The variants are listed below.
10.1 Integral automatic HX bypass (AB units only)
Intake and extract temperatures are monitored at the point the
airflows enter the unit, if the range falls within the set parameters the
bypass damper is opened automatically to target an indoor comfort
temperature all year round.
10.2 Summer / Winter Switch
When the switch position is set to Summer, the integral automatic
summer bypass is fully operational. In the alternative Winter position,
the HX bypass is disabled to ensure the unit is constantly in heat
recovery mode.
10.3 Frost Protection
In the event of the intake air temperature at the unit dropping below
the predetermined set point (-5°C as standard) the supply fan will
reduce to minimum speed, once the temperature rises above the set
point the fan will return to its commissioned speed.
Please note this mode will only activate after ten days of continuous
run time. If commissioning of the unit is outside of this timeframe
please notify the after sales department prior to site visit.
11.0 MAINTENANCE/CLEANING
We recommend that the two filters are inspected after 6 months, and
replaced every 12 to 18 months.
The filters can be removed from the unit by removing the two filter
covers on the bottom panel of the unit. Take hold of the two circular
tabs either end of the filter covers and pull to remove (see fig. 11).
The filter can now be extracted by pulling the removal loop on the edge
of the filter. Once the filters have been inspected return or replace them
as necessary.
8.2 Optional Controls For further information contact Nuaire on 02920 858 400.
Note: The display on the unit control panel will not indicate when a
higher speed setting has been triggered by an external source, such
as an ES-PIR2 etc.

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nuaire.co.uk 029 2085 8400 20. 08. 19. Leaflet Number 671876
Installation and Maintenance MRXBOXAB-ECO-LP2SW Mechanical Ventilation Unit with Heat Recovery
12.0 REPLACEMENT OF PARTS
Nuaire keep extensive stocks for quick delivery, should any component
need replacing. Ensure that the unit is electrically isolated, before
carrying out any work.
Note: The supply cable must be replaced by an electrically competent
person.
When ordering spare parts, please quote the serial number of the unit
and the ARC number of the purchase if possible (this information will
be available on the fan label).
13.0 WARRANTY
Nuaire recommend that filters are inspected every 6 months and
replaced every 12 months. A flashing LED (section 10.0) will indicate
that a filter change is required. This indication repeats every 12 months
and will turn off automatically after 5 Days.
Remove the filter covers on the front panel of the unit by gripping the
two circular tabs either end of the filter covers and pulling away from
the unit. The filter can now be extracted by pulling the removal loop on
the front edge of the filter. Once the filters have been inspected return
or replace them as necessary.
Inspect the heat exchanger every 5 years. Generally check for damage
and security of components. Refit cover.
14.0 AFTER SALES ENQUIRIES
For technical assistance or further product information, including spare
parts and replacement components, please contact the After Sales
Department.
Telephone [phone]
[e-mail]
Access to second filter Filter cover and
filter being removed
Control module
Figure 16. Remove the two filter covers on the underside panel of the
unit, and the filters can be pulled out of the unit using the tab on the
lower edge of the filter.