VOKERA Unica BHE Installation & Servicing Instructions Manual

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Unica BHE

High efficiency combi boiler

Installation
& Servicing
Instructions

0694

0694BR1207

THESE INSTRUCTIONS
TO BE RETAINED
BY USER

G.C. NUMBER

UNICA 32 BHE N° 47-094-99

Vokèra is a licensed member of the Benchmark scheme
which aims to improve the standards of installation and
commissioning of domestic hot water systems in the UK.

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Contents

Design principles & operating sequence Page

1.1 Principle components 3

1.2 Mode of operation (at rest) 3

1.3 Mode of operation (heating) 3

1.4 Mode of operation (Hot water) 3

1.5 Safety devices 3

Technical data Page

2.1 Central heating 4

2.2 Domestic hot water 4

2.3 Gas pressures 4

2.4 Expansion vessel 4

2.5 Dimensions 4

2.6 Clearances 4

2.7 Connections 4

2.8 Electrical 4

2.9 Flue details (concentric) 4

2.9A Flue details (twin pipes) 4

2.10 Efficiency 4

2.11 Emissions 4

2.12 Pump duty 5

Servicing Page

6.1 General 19

6.2 Routine annual servicing 19

6.3 Replacement of components 19

6.4 Component removal procedure 19

6.5 Pump assembly 19

6.6 Safety valve 20

6.7 Lower automatic air release valves 20

6.8 Water pressure switch 20

6.9 Primary thermistor 20

6.10 Return thermistor 20

6.11 Printed circuit board 20

6.12 Gas valve 20

6.13 Electrodes and condense sensor 21

6.14 Flue fan & mixer 21

6.15 Burner 21

6.16 Main heat exchanger 22

6.17 Automatic by-pass 22

6.18 Expansion vessel 22

6.19 Condense trap removal 22

6.20 Flue collector removal 23

General requirements (UK) Page

3.1 Related documents 6

3.2 Location of appliance 6

3.3 Gas supply 6

3.4 Flue system 6

3.5 Air supply 6

3.6 Water circulation 6

3.7 Electrical supply 7

3.8 Mounting on a combustible surface 7

3.9 Timber framed buildings 7

3.10 Inhibitors 7

3.11 Showers 7

General requirements (EIRE) Page

3A.1 Related documents 8
3A.2 Location of appliance 8
3A.3 Gas supply 8
3A.4 Flue system 8
3A.5 Air supply 8
3A.6 Water circulation 8
3A.7 Electrical supply 9
3A.8 Mounting on a combustible surface 9
3A.9 Timber framed buildings 9
3A.10Inhibitors 9
3A.11Showers 9
3A.12 Declaration of conformity 9

Installation Page

4.1 Delivery 10

4.2 Contents 10

4.3 Unpacking 10

4.4 Preparation for mounting the appliance 10

4.5 Fitting the flue 11

4.6 Connecting the gas & water 15

4.7 Electrical connections 16

Checks, adjustments and fault finding Page

7.1 Checking appliance operation 24

7.2 Appliance modes of operation 24

7.3 Appliance fan speed 25

7.4 Checking the CO2 & adjusting the valve 25

7.5 Combustion analysis test 26

7.6 Checking the expansion vessel 26

7.7 External faults 26

7.8 Electrical checks 26

7.9 Fault finding 27

7.10 Boiler configuration 27

7.11 Final fault codes 27

Wiring diagrams Page

8.1 External wiring 28

8.2 Typical control applications 28

8.3 Other devices 28

Exploded diagrams Page

9.1 Table 1 30

9.2 Table 2 31

9.3 Table 3 31

9.4 Table 4 32

9.5 Table 5 33

L.P.G. instructions Page

10.1 Related documents 34

10.2 Technical data 34

10.3 Converting the appliance gas type 34

10.4 Gas supply 34

10.5 Gas supply installation 34

10.6 Adjusting the gas valve 34

10.7 Appliance fan speed 3 5

Benchmark 36-37

Commissioning Page

5.1 Gas supply installation 17

5.2 The heating system 17

5.3 Initial filling of the system 17

5.4 Initial flushing of the system 17

5.5 Pre-operation checks 17

5.6 Initial lighting 17

5.7 Checking gas pressure & combustion analysis 17

5.8 Final flushing of the heating system 18

5.9 Setting the boiler operating temperature 18

5.10 Setting the system design pressure 18

5.11 Regulating the central heating system 18

5.12 Final checks 18

5.13 Instructing the user 18

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INTRODUCTION

The Unica BHE is a high-efficiency combination boiler with
an output to DHW of 32kW. This appliance – by design –
incorporates electronic ignition, circulating pump, expansion
vessel, safety valve, pressure gauge and automatic by­pass.
The Unica is produced as room sealed, category II2H3P
appliances, suitable for internal and external wall mounting
applications. Each appliance is provided with a fan powered
flue outlet with an annular co-axial combustion air intake
that can be rotated – horizontally – through 360 degrees for
various horizontal or vertical applications. The Unica BHE
can also be used with the Vokera twin flue system.

fig. 1

The Unica BHE is approved for use with B23, C13 & C33
type flue applications.
These appliances are designed for use with a sealed
system only; consequently they are not intended for use
on open vented systems.
This booklet is an integral part of the appliance. It is
therefore necessary to ensure that the booklet is handed
to the person responsible for the property in which the
appliance is located/installed. A replacement copy can be
obtained from Vokera customer services.
There are no banned substances used in the manufacture
of these appliances.

R

F

OI G

General layout (fig. 1)

1 Electrical connection box
2 Safety valve
3 Three port valve actuator
4 Domestic hot water heat exchanger
5 Pump
6 Bottom auto air vent (AAV)
7 Condense trap
8 Return sensor
9 Expansion vessel
10 Fumes thermostat
11 Flue gas analysis test point
12 Flue outlet & air intake
13 Ignition transformer
14 Top AAV
15 Flow sensor
16 High limit thermostat
17 Sensing Electrode
18 Spark Electrode

UNICA BHE

19 Top AAV pipe
20 Condensate level sensor
21 Cylindrical Burner
22 Main heat exchanger
23 Fan assembly
24 Mixer
25 Injector
26 Pressure switch
27 Domestic hot water sensor
28 Gas valve
29 DHW flow switch
30 Pressure gauge

R Heating return connection
F Heating flow connection
G Gas connection
O Hot water outlet
I Cold water inlet

1

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DHW

TEMPERATURE

SELECTOR

Fig. 1A

GREEN LED

2-digit LED

display

RED LED

MODE SELECTOR

SWITCH

HEATING

TEMPERATURE

SELECTOR

Hot water only Select this position if you want the boiler to supply hot water only (no heating)
Boiler at OFF/standby Select this position when you want the boiler to be s witched off f or short

periods (days) or if the boiler requires to be reset (refer to users handbook)

Heating & hot water (economy) Select this position when you want the boiler to respond to a heating request

from the time-clock/programmer

Heating & hot water with pre-heat Select this position when you want the boiler to respond to a heating request

from the time-clock/programmer (comf ort) and you want the domestic hot
water to be pre-heated

DHW temperature selector Move the selector clockwise to increase the hot water outlet temperature, or

counter-clockwise to reduce the temperature

Heating temperature selector Move the selector clockwise to increase the heating outlet temperature, or

counter-clockwise to reduce the temperature

2-digit LED display Displays the current outlet temperature of the boiler . During a fault condition,

the appropriate fault code will be displayed (refere to the users handbook for
instructions regarding fault codes)

Green LED lit Boiler is working/responding to a heating/hot water request
Red LED lit Boiler has identified a fault and has failed-safe. Refer to users handbook for

instructions on how to reset

2

UNICA BHE

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SECTION 1 DESIGN PRINCIPLES AND OPERATING SEQUENCE

1.1 PRINCIPLE COMPONENTS

• A fully integrated electronic control board featur­ing electronic temperature control, anti-cycle
control, pump over-run, self-diagnostic fault in­dicator, full air/gas modulation.

• Radial aluminium heat exchanger.

• Electronic ignition with flame supervision

• Integral high-head pump

• Fan

• Expansion vessel

• Water pressure switch

• Condensate level sensor

• Pressure gauge

• Safety valve

1.2 MODE OF OPERATION (at rest)

When the appliance is at rest and there are no
requests for heating or hot water, the following
functions are active:

• frost-protection system – the frost-protection
system protects the appliance against the risk
of frost damage both for CH and DHW. For CH
line, if the main temperature falls to 6°C, the
appliance will function on minimum power until
the temperature on main reaches 35°C.
Moreover if the DHW temperature falls to 4°C,
the appliance will function on minimum power
until the temperature on main reaches 55°C.

• anti-block function – the anti-block function
enables the pump and divertor valve actuator to
be energised for short periods, when the appli­ance has been inactive for more than 24-hours.

1.3 MODE OF OPERATION (Heating)

When there is a request for heat via the time clock
and/or any external control, the pump and fan are
started, the fan speed will modulate until the
correct signal voltage is received at the control
PCB. At this point an ignition sequence is enabled.

Ignition is sensed by the electronic circuit to
ensure flame stability at the burner. Once suc­cessful ignition has been achieved, the electronic
circuitry increases the gas rate to 75% for a period
of 15 minutes. Thereafter, the boiler’s output will
either be increase to maximum or modulate to suit
the set requirement.

When the appliance reaches the desired tempera­ture the burner will shut down and the boiler will
perform a three-minute anti-cycle (timer delay).
When the request for heat has been satisfied the
appliance pump and fan may continue to operate
to dissipate any residual heat within the appliance.

In the event of the appliance exceeding the de­sired temperature (set point) the burner will shut
down until the temperature drops. When the re­quest for DHW has been satisfied the appliance
pump and fan may continue to operate to dissi­pate any residual heat within the appliance.

1.5 SAFETY DEVICES

When the appliance is in use, safe operation is
ensured by:

• a water pressure switch that monitors system
water pressure and will de-activate the pump,
fan, and burner should the system water pressure
drop below the rated tolerance;

• fan speed sensor to ensure safe operation of the
burner;

• a high limit thermostat that over-rides the tem­perature control circuit to prevent or interrupt the
operation of the burner;

• flame sensor that will shut down the burner when
no flame signal is detected;

• a sensor that interrupts the operation of the
appliance if the condense pipe becomes blocked;

• a safety valve which releases excess pressure
from the primary circuit.

Return

temperature

sensor

Expansion

vessel

Pump

Bottom

AAV

Pressure

switch

DHW heat
exchanger

Top AAV

Flow temperature

sensor

Main heat

exchanger

DHW

temperature

sensor

1.4 MODE OF OPERATION (Hot water)

When there is a request for DHW via a hot water
outlet or tap, the pump and fan are star ted, the
fan speed will modulate until the correct signal
voltage is received at the control PCB. At this
point an ignition sequence is enabled.

Ignition is sensed by the electronic circuit to en­sure flame stability at the burner. Once success­ful ignition has been achieved, the electronic cir­cuitry increases the gas rate to maximum or will

Fig. 2

modulate output to stabilise the temperature.

UNICA BHE

Diverter

valve

Automatic

by-pass

CH

return

Drain
valve

CH

flow

DHW

outlet

DHW

inlet

DHW flow

switch

3

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SECTION 2 TECHNICAL DATA

2.1 Central Heating Unica 32BHE

Heat input (kW) 25
Maximum heat output (kW) 60/80°C 24.45
Minimum heat output (kW) 60/80°C 6.90
Maximum heat output (kW) 30/50°C 26.30
Minimum heat output (kW) 30/50°C 7.47
Minimum working pressure 0.5 bar
Maximum working pressure 3 bar
Minimum flow rate 1000 l/h

2.2 Domestic Hot Water Unica 32BHE

Heat input (kW) 32
Flow Rate: ∆T35oC 13.1 l/pm
Maximum inlet pressure 6.0 bar
Minimum inlet pressure 0.15 bar
Minimum flow rate 350 l/h

2.3 Gas Pressures Unica 32BHE

Inlet pressure (G20) 20.0 mbar
Heating maximum gas rate (m3/hr) 2.64
DHW maximum gas rate (m3/hr) 3.38
Minimum gas rate (m3/hr) 0.74
Injector size (mm) 6.7

2.4 Expansion Vessel Unica 32BHE

Capacity 10-litres
Maximum system volume 91-litres
Pre-charge pressure 1.0 bar

2.5 Dimensions Unica 32BHE

Height (mm) 785
Width (mm) 553
Depth (mm) 268
Dry weight (kg) ??

2.6 Clearances UNICA BHE Range

Sides Left= 12mm - Right= 25mm
To p 150mm from casing or 25mm above flue elbow (whichever is applicable)
Bottom 150mm
Front 600mm

2.7 Connections UNICA BHE Range

Flow & return 22mm
Gas 15mm
DHW hot & cold 15mm
Safety valve 15mm
Condense 21mm

2.8 Electrical Unica 32BHE

Power consumption (Watts) 150W
Voltage (V/Hz) 230/50
Internal fuse 3.15A T (for PCB) - 3.15A F (for connections block)
External fuse 3A

2.9 Flue Details (concentric) Unica 32BHE

Maximum horizontal flue length (60/100mm) 7.8m
Maximum vertical flue length (60/100mm) 8.8m
Maximum horizontal flue length (80/125mm) 20 m
Maximum vertical flue length (80/125mm) 25m

2.9A Flue Details (twin pipes) Unica 32BHE

Maximum horizontal flue length (80mm/80mm) 40m/40m
Maximum vertical flue length (80mm/80mm) 40m/40m

2.10 Efficiency Unica 32BHE
SEDBUK (%) 90.2

2.11 Emissions Unica 32BHE

CO2 @ maximum output (%) 9.0
CO2 @ minimum output (%) 9.0
CO/CO2 ratio @ maximum output 0.002 to 1
CO/CO2 ratio @ minimum output 0.0001 to 1
CO @ maximum output (mg/kWh) 156.0
CO @ minimum output (mg/kWh) 7.0
NOx @ maximum output mg/kWh) 45.0
NOx @ minimum output (mg/kWh) 20.0
NOx rating class 5

4

UNICA BHE

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2.12 PUMP DUTY

Fig. 3 shows the flow-rate available – after allowing
for pressure loss through the appliance – for
system requirements. When using this graph,
apply only the pressure loss of the system. The
graph is based on a 20oC temperature differential.

Fig. 3

5,0
4,8
4,6
4,4
4,2
4,0
3,8
3,6
3,4
3,2
3,0
2,8
2,6
2,4
2,2
2,0
1,8
1,6
1,4
1,2
1,0

Residual head (x 100 mbar)

0,8
0,6
0,4
0,2
0,0

0 100 200 300 400 500 600 700 800 900 1000 1100 1200 1300 1400 1500

1st speed

2nd speed

3rd speed

Flow rate (l/h)

Fig. 4

Key Location Minimum distance

A Below an opening (window, air-brick, etc.) 300 mm
B Above an opening (window, air-brick, etc.) 300 mm
C To the side of an opening (window, air-brick, etc.) 300 mm
D Below gutter, drain-pipe, etc. 25 mm
E Below eaves 25 mm

F Below balcony, car-port roof, etc. 25 mm
G To the side of a soil/drain-pipe, etc. 25 mm (60mm for 80/125, 5” flue)
H From internal/external corner 25 mm (60mm for 80/125, 5” flue)

I Above ground, roof, or balcony level 300 mm
J From a surface or boundary facing the terminal 600 mm
K From a terminal facing a terminal 1200 mm
L From an opening in the car-port into the building 1200 mm

M Vertically from a terminal on the same wall 1500 mm
N Horizontally from a terminal on the same wall 300 mm

P From a structure to the side of the vertical terminal 300 mm

Q From the top of the vertical terminal to the roof flashing As determined by the fixed collar

of the terminal

R To the side of a boundary 300 mm

S To the side of an opening or window on a pitched roof 600 mm
T Below an opening or window on a pitched roof 2000 mm
V From a vertical terminal to an adjacent opening (window, air-brick, etc) (call Vokera technical for advice)

W From a vertical terminal to an adjacent vertical terminal 300 mm* (Only if both terminals are the same hight)

UNICA BHE

5

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SECTION 3 GENERAL REQUIREMENTS (UK)

This appliance must be installed by a competent
person in accordance with the Gas Safety (In­stallation & Use) Regulations.

3.1 RELATED DOCUMENTS

The installation of this boiler must be in accord­ance with the relevant requirements of the Gas
Safety (Installation & Use) Regulations, the local
building regulations, the current I.E.E. wiring regu­lations, the bylaws of the local water undertaking,
the Building Standards (Scotland) Regulation and
Building Standards (Northern Ireland) Regulations.
It should be in accordance also with any relevant
requirements of the local authority and the rel­evant recommendations of the following British
Standard Codes of Practice.

3.2 LOCATION OF APPLIANCE

The appliance may be installed in any room or
internal space, although particular attention is
drawn to the requirements of the current I.E.E.
wiring regulations, and in Scotland, the electrical
provisions of the Building Regulations, with respect
to the installation of the appliance in a room or
internal space containing a bath or shower.
When an appliance is installed in a room or internal
space containing a bath or shower, the appliance

adequate air supply for combustion purposes and
an adequate space for servicing and air circulation
around the appliance. Where the installation of the
appliance will be in an unusual location special
procedures may be necessary, refer to I.S. 813 for
detailed guidance on this aspect.
A compartment used to enclose the appliance
must be designed and constructed specifically for
this purpose. An existing compartment/cupboard
may be utilised provided that it is modified to suit.

3.3 GAS SUPPLY

The gas meter – as supplied by the gas supplier –
must be checked to ensure that it is of adequate
size to deal with the maximum rated input of all the
appliances that it serves. Installation pipes must
be fitted in accordance with BS 6891.

Pipe work from the meter to the appliance must
be of adequate size. Pipes of a smaller size than
the appliance gas inlet connection must not be
used. The installation must be tested f or tightness
in accordance with BS6891.
If the gas supply serves more than one appliance,
it must be ensured that an adequate supply is
maintained to each appliance when they are in
use at the same time.

BS 5440 PART 1 FLUES
BS 5440 PART 2 FLUES & VENTILATION
BS 5449 PART 1 FORCED CIRCULATION HOT WATER SYSTEMS
BS 5546 INSTALLATION OF GAS HOT WATER SUPPLIES FOR DOMESTIC PURPOSES
BS 6798 INSTALLATION OF BOILERS OF RATED INPUT NOT EXCEEDING 60kW
BS 6891 LOW PRESSURE INSTALLATION PIPES
BS 7074 PART 1 APPLICATION, SELECTION, AND INSTALLTION OF EXPANSION VESSELS

AND ANCILLARY EQUIPMENT FOR SEALED WATER SYSTEMS

or any control pertaining to it must not be within
reach of a person using the bath or shower.
The location chosen for the appliance must permit
the provision of a safe and satisfactory flue and
termination. The location must also permit an
adequate air supply for combustion purposes and
an adequate space for servicing and air circulation
around the appliance. Where the installation of the
appliance will be in an unusual location special
procedures may be necessary, BS 6798 gives
detailed guidance on this aspect.
A compartment used to enclose the appliance
must be designed and constructed specifically for
this purpose. An existing compartment/cupboard
may be utilised provided that it is modified to suit.
Details of essential features of compartment/
cupboard design including airing cupboard
installations are given in BS 6798.

3A.2 LOCATION OF APPLIANCE

The appliance may be installed in any room or
internal space, although particular attention is
drawn to the requirements of the current ETCI
National Rules for Electrical Installations, and I.S.
813, Annex K.
When an appliance is installed in a room or internal
space containing a bath or shower, the appliance
or any control pertaining to it must not be within
reach of a person using the bath or shower.
The location chosen for the appliance must permit
the provision of a safe and satisfactory flue and
termination. The location must also permit an

3.4 FLUE SYSTEM

The terminal should be located where the disper­sal of combustion products is not impeded and
with due regard for the damage and discoloration
that may occur to building products located nearby.
The terminal must not be located in a place where
it is likely to cause a nuisance (see fig. 4).
In cold and/or humid weather, water vapour will
condense on leaving the terminal; the effect of
such pluming must be considered.
If installed less than 2m above a pavement or
platform to which people have access (including
balconies or flat roofs) the terminal must be
protected by a guard of durable material.
The guard must be fitted centrally over the termi­nal. Refer to BS 5440 Part 1, when the terminal is

0.5 metres (or less) below plastic guttering or 1
metre (or less) below painted eaves.

3.5 AIR SUPPLY

The following notes are intended for general guid­ance only. This appliance is a room-sealed, fan­flued boiler, consequently it does not require a
permanent air vent for combustion air supply.
When installed in a cupboard or compartment,
ventilation for cooling purposes is also not required.

3.6 WATER CIRCULATION

Detailed recommendations are given in BS 5449
Part 1 and BS 6798. The following notes are for
general guidance only.

3.6.1 PIPEWORK

It is recommended that copper tubing to BS 2871

6

UNICA BHE

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Part 1 is used in conjunction with soldered capil­lary joints. Where possible pipes should have a
gradient to ensure air is carried naturally to air
release points and that water flows naturally to
drain cocks. Except where providing useful heat,
pipes should be insulated to avoid heat loss and in
particular to avoid the possibility of freezing.
Particular attention should be paid to pipes pass­ing through ventilated areas such as under floors,
loft space and void areas.

3.6.2 AUTOMATIC BY-PASS

The appliance has a built-in automatic by-pass,
consequently there is no requirement for an exter­nal by-pass, however the design of the system
should be such that it prevents boiler ‘cycling’.

3.6.3 DRAIN COCKS

These must be located in accessible positions to
facilitate draining of the appliance and all water
pipes connected to the appliance. The drain cocks
must be manufactured in accordance with BS 2879.

3.6.4 AIR RELEASE POINTS

These must be positioned at the highest points in
the system where air is likely to be trapped. They
should be used to expel trapped air and allow
complete filling of the system.

3.6.5 EXPANSION VESSEL

The appliance has an integral expansion vessel to
accommodate the increased volume of water
when the system is heated. It can accept up to 8
(28HE) or 10 (32 & 36HE) litres of expansion from
within the system, generally this is sufficient,
however if the system has an unusually high water
content, it may be necessary to provide additional
expansion capacity (see 6.19).

3.6.6 FILLING POINT

A method for initial filling of the system and replac­ing water lost during servicing etc. directly from the
mains supply , is provided (see fig. 5). This method
of filling complies with the current Water Supply
(Water Fittings) Regulations 1999 and Water By­laws 2000 (Scotland). If an alternative location is
preferred, it should be connected as detailed in fig.5.

pipe

control

valve

temporary

connection

double

check valve

control

valve

supply

pipe

fig.5

flow/return

3.6.7 LOW PRESSURE SEALED SYSTEM

An alternative method of filling the system would
be from an independent make-up vessel or tank
mounted in a position at least 1 metre above the
highest point in the system and at least 5 metres
above the boiler (see fig. 5A).
The cold feed from the make-up vessel or tank
must be fitted with an approved non-return valve
and stopcock for isolation purposes. The f eed pipe
should be connected to the return pipe as close
to the boiler as possible.

3.6.8 FREQUENT FILLING

Frequent filling or venting of the system may be

indicative of a leak. Care should be taken during
the installation of the appliance to ensure all
aspects of the system are capable of withstanding
pressures up to at least 3 bar.

Make-up vessel
or tank

Automatic
air-vent

Non-return

valve

fig.5A

Stopcock

5.0 metres minimum

Heating
return

3.7 ELECTRICAL SUPPLY

The appliance is supplied for operation on 230V @
50Hz electrical supply; it must be protected with a
3-amp fuse. The method of connection to the
mains electricity supply must allow for complete

isolation from the supply. The preferred method is
by using a double-pole switch with a contact
separation of at least 3

,5mm (3° high-voltage

category). The switch must only supply the appli-

ance and its corresponding controls, i.e. time
clock, room thermostat, etc. Alternatively an un­switched shuttered socket with a fused 3-pin plug
both complying with BS 1363 is acceptable.

3.8 MOUNTING ON A COMBUSTIBLE SURFACE
If the appliance is to be fitted on a wall of combus­tible material, a sheet of fireproof material must
protect the wall.

3.9 TIMBER FRAMED BUILDINGS

If the appliance is to be fitted in a timber framed
building, it should be fitted in accordance with the
Institute of Gas Engineers publication (IGE/UP/7)
‘Guide for Gas Installations in Timber Frame
Buildings’.

3.10 INHIBITORS

Vokera recommend that an inhibitor - suitable for
use with copper and aluminium heat exchangers

- is used to protect the boiler and system from
the effects of corrosion and/or electrolytic action.
The inhibitor must be administered in strict ac­cordance with the manufacturers instructions*.

*Water treatment of the complete heating system

- including the boiler - should be carried out in
accordance with BS 7593 and the Domestic Water
Treatment Association’s (DWTA) code of prac­tice.

3.11 SHOWERS

If the appliance is intended for use with a shower,
the shower must be thermostatically controlled
and be suitable for use with a combination boiler.

UNICA BHE

7

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SECTION 3A GENERAL REQUIREMENTS (EIRE)

This appliance must be installed by a competent
person in accordance with and defined by, the
Standard Specification (Domestic Gas Installa­tions) Declaration (I.S. 813).

3A.1 RELATED DOCUMENTS

The installation of this boiler must be in accord­ance with the relevant requirements of the local
building regulations, the current ETCI National
Rules for Electrical Installations and the bylaws of
the local water undertaking.
It should be in accordance also with any relevant
requirements of the local and/or district authority.

3A.2 LOCATION OF APPLIANCE

The appliance may be installed in any room or
internal space, although particular attention is
drawn to the requirements of the current ETCI
National Rules for Electrical Installations, and I.S.
813, Annex K.
When an appliance is installed in a room or internal
space containing a bath or shower, the appliance
or any control pertaining to it must not be within
reach of a person using the bath or shower.
The location chosen for the appliance must permit
the provision of a safe and satisfactory flue and
termination. The location must also permit an
adequate air supply for combustion purposes and
an adequate space for servicing and air circulation
around the appliance. Where the installation of the
appliance will be in an unusual location special
procedures may be necessary, refer to I.S. 813 for
detailed guidance on this aspect.
A compartment used to enclose the appliance
must be designed and constructed specifically for
this purpose. An existing compartment/cupboard
may be utilised provided that it is modified to suit.
This appliance is not suitable for external instal­lation.

3A.3 GAS SUPPLY

The gas meter – as supplied by the gas supplier –
must be checked to ensure that it is of adequate
size to deal with the maximum rated input of all the
appliances that it serves. Installation pipes must
be fitted in accordance with I.S. 813.
Pipe work from the meter to the appliance must
be of adequate size. Pipes of a smaller size than
the appliance gas inlet connection must not be
used. The installation must be tested for tightness
in accordance with I.S. 813.
If the gas supply serves more than one appliance,
it must be ensured that an adequate supply is
maintained to each appliance when they are in
use at the same time.

3A.4 FLUE SYSTEM

The terminal should be located where the disper­sal of combustion products is not impeded and
with due regard for the damage and discoloration
that may occur to building products located nearby.
The terminal must not be located in a place where
it is likely to cause a nuisance (see I.S. 813).
In cold and/or humid weather, water vapour will
condense on leaving the terminal; the effect of
such pluming must be considered.
If installed less than 2m above a pavement or
platform to which people have access (including
balconies or flat roofs) the terminal must be
protected by a guard of durable material. The
guard must be fitted centrally over the terminal.

Refer to I.S. 813, when the terminal is 0.5 metres
(or less) below plastic guttering or 1 metre (or less)
below painted eaves.

3A.5 AIR SUPPLY

The following notes are intended for general guid­ance only.
This appliance is a room-sealed, fan-flued boiler,
consequently it does not require a permanent air
vent for combustion air supply.
When installed in a cupboard or compartment,
ventilation for cooling purposes is also not re­quired.

3A.6 WATER CIRCULATION

Specific recommendations are given in I.S. 813.
The following notes are for general guidance only.

3A.6.1 PIPEWORK

It is recommended that copper tubing be used in
conjunction with soldered capillary joints.
Where possible pipes should have a gradient to
ensure air is carried naturally to air release points
and that water flows naturally to drain cocks.
Except where providing useful heat, pipes should
be insulated to avoid heat loss and in particular to
avoid the possibility of freezing. Particular atten­tion should be paid to pipes passing through
ventilated areas such as under floors, loft space
and void areas.

3A.6.2 AUTOMATIC BY-PASS

The appliance has a built-in automatic by-pass,
consequently there is no requirement for an exter­nal by-pass, however the design of the system
should be such that it prevents boiler ‘cycling’.

3A.6.3 DRAIN COCKS

These must be located in accessible positions to
facilitate draining of the appliance and all water
pipes connected to the appliance.

3A.6.4 AIR RELEASE POINTS

These must be positioned at the highest points in
the system where air is likely to be trapped. They
should be used to expel trapped air and allow
complete filling of the system.

3A.6.5

3A.6.6 FILLING POINT

3A.6.7 LOW PRESSURE SEALED SYSTEM

EXPANSION VESSEL

The appliance has an integral expansion vessel to
accommodate the increased volume of water
when the system is heated. It can accept up to 8
(28HE) or 10 (32 & 36HE) litres of expansion from
within the system, generally this is sufficient,
however if the system has an unusually high water
content, it may be necessary to provide additional
expansion capacity (see 6.19).

A method for initial filling of the system and
replacing water lost during servicing etc. is pro­vided (see fig.8). You should ensure this method
of filling complies with the local water authority
regulations.

An alternative method of filling the system would
be from an independent make-up vessel or tank
mounted in a position at least 1 metre above the
highest point in the system and at least 5 metres
above the boiler (see fig. 5A). The cold feed from
the make-up vessel or tank must be fitted with an
approved non-return valve and stopcock for isola­tion purposes. The feed pipe should be connected
to the return pipe as close to the boiler as possible.

8

UNICA BHE

Supplied By www.heating spares.co Tel. [phone]

3A.6.8 FREQUENT FILLING

Frequent filling or venting of the system may be
indicative of a leak. Care should be taken during
the installation of the appliance to ensure all
aspects of the system are capable of withstanding
pressures up to at least 3 bar.

3A.7 ELECTRICAL SUPPLY

The appliance is supplied for operation on 230V @
50Hz electrical supply; it must be protected with a
3-amp fuse. The method of connection to the
mains electricity supply must allow for complete
isolation from the supply. The preferred method is
by using a double-pole switch with a contact
separation of at least 3,5 mm (3° high-voltage
category). The switch must only supply the appli­ance and its corresponding controls, i.e. time
clock, room thermostat, etc.

3A.8 MOUNTING ON A COMBUSTIBLE SURFACE

If the appliance is to be fitted on a wall of combus­tible material, a sheet of fireproof material must
protect the wall.

3A.9 TIMBER FRAMED BUILDINGS

If the appliance is to be fitted in a timber framed
building, it should be fitted in accordance with I.S.
813 and local Building Regulations.

The Institute of Gas Engineers publication (IGE/
UP/7) ‘Guide for Gas Installations in Timber Frame
Buildings’ gives specific advice on this type of
installation.

3A.10 INHIBITORS

Vokera recommend that an inhibitor - suitable for
use with aluminium heat exchangers - is used to
protect the boiler and system from the effects of
corrosion and/or electrolytic action. The inhibitor
must be administered in strict accordance with
the manufacturers instructions*.

*Water treatment of the complete heating system

- including the boiler - should be carried out in
accordance with I.S. 813 and the Domestic Water
Treatment Association’s (DWTA) code of prac­tice.

3A.11 SHOWERS

If the appliance is intended for use with a shower,
the shower must be thermostatically controlled
and be suitable for use with a combination boiler.

3A.12 DECLARATION OF CONFORMITY

A Declaration of Conformity (as defined in I.S.

813) must be provided on completion of the in­stallation.
A copy of the declaration must be given to the
responsible person and also to the gas supplier if
required.

fig. 6

fig. 7

Cold water inlet

stopcock/filling

valve

fig. 8

UNICA BHE

C/H flow

valve

C/H return

valve

Hot water

outlet

Default screws position of fixing jig: No. 3

Gas

cock

9

Supplied By www.heating spares.co Tel. [phone]

SECTION 4 INSTALLATION

4.1 DELIVERY

Due to the weight of the appliance it may be
necessary for two people to lift and attach the
appliance to its mounting. The appliance is con­tained within a heavy-duty cardboard carton. Lay
the carton on the floor with the writing the correct
way up.

4.1.2 APPLICATION

The Unica BHE can be installed within the property
or external to the property. Although the appliance
is certified IPx5D, if it’s to be installed externally,
it may be necessary to provide reasonable
protection from heavy or persistent rain however
this will be purely dependant on the location of the
appliance and local conditions. Alternatively, the
appliance enclosure (see fig 1B) can be used (not
supplied).

4.2 CONTENTS

Contained within the carton is:

• the boiler

• the wall bracket & fixing jig

• template

• an accessories pack containing appliance serv-

ice connections and washers

• the instruction pack containing the installation &
servicing instructions, user instructions, guar­antee registration card and a 3-amp fuse.

4.3 UNPACKING

At the top of the carton pull both sides open – do
not use a knife – unfold the rest of the carton from
around the appliance, carefully remove all protec­tive packaging from the appliance and lay the
accessories etc. to one side. Protective gloves
should be used to lift the appliance, the appliance
back-frame should be used for lifting points.

4.3.2 PREPARATION FOR MOUNTING THE
APPLIANCE (external application)
The appliance and/or the appliance enclosure

should be mounted on a smooth, vertical,
noncombustible surface, which must be capable
of supporting the full weight of the appliance and/
or enclosure. Care should be exercised when
determining the position of the appliance with
respect to hidden obstructions such as pipes,
cables, etc. When the position of the appliance
has been decided - using the template supplied ­carefully mark the position of the wall-mounting
bracket (see fig. 6) and flue-hole (if applicable).

4.3.3 IMPORTANT

The Unica BHE can be used on various applications

(4.1.2). The following instructions relate to
external applications, i.e. external to the
property or dwelling.

4.4 PREPARATION FOR MOUNTING THE APPLI­ANCE

The appliance should be mounted on a smooth,
vertical, non-combustible surface, which must be
capable of supporting the full weight of the appli­ance. Care should be exercised when determining
the position of the appliance with respect to hidden
obstructions such as pipes, cables, etc.
When the position of the appliance has been

decided – using the template supplied – carefully
mark the position of the wall-mounting bracket
(see fig. 8) and flue-hole (if applicable). If you
intend to run the pipe-work vertically behind the
boiler, move the screws on the fixing jig from the
default position (No. 3) to position No. 5. You will
also require a spacer kit, part No. 435 (see 4.6).

4.4.1 EXTERNAL APPLICATIONS USING THE
ENCLOSURE

The Unica BHE boiler can be used withthe enclosure
(fig 1B). The Enclosure has been designed to be
recessed into an external wall or surface to give a
flush finish. It can however, be mounted onto an
external wall if required.
Should this application be preferred, it’s
recommended that any openings on the top of the
enclosure are sealed with a suitable silicone sealant
in order to minimise the ingress or rainwater.
The use of the enclosure allows the installation
pipework to be installed prior to the appliance
being installed.
Due to the enclosure being installed external to the
property, the flueing arrangements for the appliance
can be simplified.

PREPARATION

Refer to the enclosure instructions (supplied) for
specific installation instructions and details on the
required size of opening.
The enclosure is supplied with ‘knock-out’ panels
that allow the appliance flue outlet to routed to the
left, right, or vertically.
In addition, the flue can be routed through the front
of the enclosure.
The route and termination of the flue outlet must be
considered prior to the installation of the enclosure.
Refer to the relevant sections within this installation
booklet and the enclosure instructions for guidance,
and Install the pipework and electrical supply prior
to the fixing of the enclosure. Additionally, if the
flue system is to be routed within the fabric of the
property, then it’s advisable to carry this out before
fitting the enclosure.
At this point it will be necessary to remove the
‘knock-out’ panels that are specific to the route of
the flue system and pipework.

FIXING

Secure the enclosure to the wall using the relevant
fixing points, taking care to ensure that it is level
and corresponds to the pre-installed pipework and/
or flue system.
Alternatively the enclosure can be secured to an
external wall by modifying the rear panel to accept
fixing screws or bolts.

MOUNTING THE APPLIANCE

Mount the appliance onto the enclosure as indicated
in the enclosure instructions.

4.4.2 EXTERNAL APPLICATIONS WITHOUT THE
ENCLOSURE

The Unica boiler can be installed without the
requirement of an enclosure providing that some
form of protection is used to minimise the risk of
water penetration into the appliance (see fig 9A).

PREPARATION

Using the template and details in figure 6 and 7 as
a guide, secure the appliance wall bracket to the
external wall and mount the appliance to the wall
bracket.

10

UNICA BHE