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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.

MRXBOX95B-LP1H

Mechanical Ventilation Unit with Heat Recovery 

Summer Bypass & Integral Humidistat

Installation and Maintenance

Nuaire Limited

Western Industrial Estate  Caerphilly  United Kingdom  CF83 1NA  

T: 029 2085 8400  F: 029 2085 8444  E: [email protected]  W: www.nuaire.co.uk

1

24. 06. 13. Leaflet Number 671607

Spigot 1.

Spigot 4.

Spigot 3. 

Spigot 2.

Figure 1. Airflow through unit.

Spigots 1 to 4

1.

Intake air (Fresh Air from outside).

2. Supply Air (Supply in to house).

3. Extract Air (Warm air from house).

4. Exhaust Air (Waste air to outside).

The EMC Directive 
2004/108/EC  
The Low Voltage 
Directive 
2006/95/EC

Figure 2. Installing the unit using appropriate fixing bolts.

204 x 60mm 
ducting in 
ceiling void.

Side view of unit 
mounted in the ceiling void.

Air valve 
in ceiling.

Figure 3. Typical side view example of a unit mounted in a ceiling
void using 204 x 60mm rectangular ducting and air valves.

Steel mounting bracket

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.

1.0 Introduction

MRXBOX95B-LP1H ceiling void mounted unit is designed to 
provide mechanical supply and extract ventilation with heat
recovery, summer bypass & incorporates integral humidistat.

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.

The bypass damper opens automatically via a wax actuator when

the outside air reaches 20°C, when the outer air temperature

returns below this level the unit returns to its original state.

Outside air supplied through the bypass is still being filtered, 

so the air quality is optimal, irrespective of the bypass setting

(open or closed).

The unit is fitted with a frost protection mode, in the event of the

fresh air temperature dropping below -5 Deg C the supply fan will

switch off. The unit will then automatically switch back on when

the temperature raises back above -5 Deg C.

2.0 Installation

Installation must be carried out by competent personnel in

accordance with the appropriate authority and conforming 

to all statutory 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. 

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).

1. The unit is supplied with a steel mounting bracket.

2. 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.

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.

Summary of Contents for MRXBOX95B-LPIH

Page 1: ... 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 The bypass damper opens automatically via a wax actuator when the outside air reaches 20 C when the outer air temperature returns below this level the unit returns to its original state Outside air supplied through the bypass is still being filtered so the ...

Page 2: ...ustable valve types not supplied External grilles to have a minimum free area of 12 250 sq mm 2 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 ...

Page 3: ...nd 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 ...

Page 4: ...t no V125S in ceilings Exhaust air from kitchen bathroom to outside via air brick Part no PVC505NS Supply and extract ducts from external air bricks to the unit needs to be insulated Minimum 300mm Top of ceiling void Intake air from outside via air brick Part no PVC505NS 3 0 Dimensions mm Figure 5 Also shows the working space required View from top with lid A 700 View from control side 668 hole ce...

Page 5: ...itch Grey Grey Green yellow Unit serving kitchen and bathroom Unit serving kitchen and two bathrooms Figure 8 Figure 9 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 Figure 7 5 0 Electrical Connection Please note the electrical connection of the unit must be be carried out ...

Page 6: ...an to maximum airflow See wiring diagram for details of operating this facility 6 2 Humidity adjustment This product contains an internal humidity sensor fitted into the airflow extracting from the wet rooms When the unit senses that the humidity exceeds the set point the unit will boost to that set by the commissioned boost speed The set point can be found on the bottom of the unit see fig 10 and...

Page 7: ...the impeller being affected 3 2 When handling the equipment care should be taken with corners and edges and that the weight distribution within the unit is considered Lifting gear such as slings or ropes must be arranged so as not to bear on the casing 3 3 Equipment stored on site prior to installation should be protected from the weather and steps taken to prevent ingress of contaminants 4 0 OPER...

Page 8: ...lings assessed under The Building Regulations 2010 specifically SAP 2009 and Approved Documents L and F Completion of this document is therefore only required for dwellings assessed by SAP 2005 Customer Details Customer Name Address Telephone Number Date of Installation Name of Lead Contractor Design Project Number It should be noted that this guidance is not intended to replace product manufactur...

Page 9: ...or to overcome particular obstructions If flexible ducting has been used has it been pulled taut to minimise system resistance Has the number of duct bends been minimised to ensure adequate air flow and least resistance Bends should have a minimum radius at least the same as the diameter of the ducting used Refer to Figure 1 if using flexible ducting Have the fans and ducting placed in unheated vo...

Page 10: ...ry unit been fixed to a stable element of the building fabric e g wall or floor using manufacturer recommended supplied fixing brackets Has the condensation drain been fitted and the pipe insulated Have approved acoustic anti vibration mountings been used Note Special attention is needed to avoid transmission and stress to duct joints Has the unit been installed in a position that will permit acce...

Page 11: ... or N A Has the rating label been verified to establish suitability for the installation strategy and whether an earth is required e g voltage class I or II product status Has a local isolator been provided to enable the unit to be isolated for maintenance purposes Has the unit been fused in accordance with its power rating SECTION 2 COMMISSIONING GUIDANCE ...

Page 12: ...ution grilles been locked where possible to minimise unapproved occupant adjustment Figure 3 Ensure all external and internal windows and doors are closed Set fan speed using manufacturer data table Set normal daytime air flow on extract points starting at location furthest from unit Set normal daytime air flow on input points starting at location furthest from unit Step 1 Step 2 Step 3 Step 4 Ste...

Page 13: ...he customer been advised that opening windows is not recommended during normal use in order to ensure the energy efficient operation and performance of the balanced system Has the customer been advised not to seal natural air flows from room to room e g avoid door seals and thick pile carpets Has the customer been advised not to alter settings post commissioning Has the customer been advised to cl...

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