vokera Unica 28 HE User guide

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Unica HE

High efficiency combi boiler

Installation

& Servicing

Instructions

THESE INSTRUCTIONS TO BE RETAINED BY USER

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.

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

2.9B Flue details (80/125) 4

2.10 Efficiency 4

2.11 Emissions 4

2.12 Pump duty 5

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

Servicing Page

6.1 General 18

6.2 Routine annual servicing 18

6.3 Replacement of components 18

6.4 Component removal procedure 18

6.5 Pump assembly 18

6.6 Safety valve 19

6.7 Lower automatic air release valves 19

6.8 Water pressure switch 19

6.9 Primary thermistor 19

6.10 Return thermistor 19

6.11 Printed circuit board 19

6.12 Gas valve 19

6.13 Electrodes and condense sensor 20

6.14 Flue fan & mixer 20

6.15 Burner 20

6.16 Main heat exchanger 20

6.17 Automatic by-pass 21

6.18 Expansion vessel 21

6.19 Condense trap removal 21

6.20 Flue collector removal 21

Checks, adjustments and fault finding Page

7.1 Checking appliance operation 23

7.2 Appliance modes of operation 23

7.3 Appliance fan speed 24

7.4 Checking the CO2 & adjusting the valve 24

7.5 Combustion analysis test 25

7.6 Checking the expansion vessel 25

7.7 External faults 25

7.8 Electrical checks 25

7.9 Fault finding 26

7.10 Component values & characteristics 26

7.11 Final fault codes 26

7.12 Boiler configuration 26

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.10 Inhibitors 9 3A.11 Showers 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 10

4.6 Connecting the gas & water 14

4.7 Electrical connections 15

Commissioning Page

5.1 Gas supply installation 16

5.2 The heating system 16

5.3 Initial filling of the system 16

5.4 Initial flushing of the system 16

5.5 Pre-operation checks 16

5.6 Initial lighting 16

5.7 Checking gas pressure & combustion analysis 16

5.8 Final flushing of the heating system 17

5.9 Setting the boiler operating temperature 17

5.10 Setting the system design pressure 17

5.11 Regulating the central heating system 17

5.12 Final checks 17

5.13 Instructing the user 17

Wiring diagrams Page

8.1 External wiring 27

8.2 Typical control applications 27

8.3 Other devices 27

8.4 Vokera twin-channel programmer 27

Exploded diagrams Page

9.1 Table 1 29

9.2 Table 2 30

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 35

Benchmark 36

INTRODUCTION

The Unica HE comprises a range of high-efficiency combination boilers with outputs to DHW of 28kW, 32kW, and 36kW respectively. These appliances – by design – incorporate electronic ignition, circulating pump, expansion vessel, safety valve, pressure gauge, and automatic by-pass.

The Unica range is produced as room sealed, category II2H3P appliances, suitable for internal wall mounting applications only. 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

fig. 1

R F G O I

Unica HE can also be used with the Vokera twin flue system. The Unica HE is approved for use with 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.

General layout (fig. 1)

1 Three porte valve actuator 2 Drain valve 3 Safety valve 4 Pressure switch 5 Pump 6 Bottom auto air vent (AAV) 7 Injector 8 Condense trap 9 Return sensor 10 Flue gas analysis test point 11 Flue outlet & air intake 12 Ignition transformer 13 Top AAV 14 Flow sensor 15 High limit thermostat 16 Limit thermostat 17 Sensing Electrode 18 Spark Electrode 19 Cylindric Burner 20 Condensate level sensor 21 Main heat exchanger 22 Top AAV pipe 23 Fan assembly 24 Mixer 25 Expansion vessel 26 Domestic hot water sensor 27 Domestic hot water heat exchanger 28 DHW flow switch 29 Gas valve 30 Condensing drain

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

R F G O I

The Unica HE is approved for use with C13 & C33 type flue applications.

DHW

TEMPERATURE

SELECTOR

HYDROMETRE

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 switched off 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 (comfort) 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

Pressure gauge Ensure the system pressure is set correctly (minimum 0.5-bar)

SECTION 1 DESIGN PRINCIPLES AND OPERATING SEQUENCE

1.1 PRINCIPLE COMPONENTS

• A fully integrated electronic control board featuring electronic temperature control, anticycle 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 24hours.

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.

electronic circuitry increases the gas rate to maximum or will modulate output to stabilise the temperature.

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

Top AAV

Flow temperature

sensor

Main heat

exchanger

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.

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 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

Expansion

vessel

Fig. 2

Pump

Diverter

valve

Automatic

by-pass

Safety

valve

Bottom

AAV

return

Pressure

switch

Drain valve

flow

DHW

non return

valve

DHW heat exchanger

DHW

outlet

DHW

temperature

sensor

DHW flow

DHW

inlet

Flow

regulator

switch

SECTION 2 TECHNICAL DATA

2.1 Central Heating Unica 28HE Unica 32HE Unica36HE

Heat input (kW) 20 25 30 Maximum heat output (kW) 60/80°C 19.6 24.45 29.31 Minimum heat output (kW) 60/80°C 5.9 6.9 6.84 Maximum heat output (kW) 30/50°C 21.00 26.30 31.83 Minimum heat output (kW) 30/50°C 6.40 7.47 7.41 Minimum working pressure 0.5 bar Maximum working pressure 2.7 bar Minimum flow rate 350 l/h

2.2 Domestic Hot Water Unica 28HE Unica 32HE Unica36HE

Heat input (kW) 28 32 36 Flow Rate: ∆T35oC 11.5 l/pm 13.1 l/pm 14.7 l/pm Maximum inlet pressure 6.0 bar Minimum inlet pressure 0.15 bar Minimum flow rate 2.0 l/min

2.3 Gas Pressures Unica 28HE Unica 32HE Unica36HE

Inlet pressure (G20) 20.0 mbar Heating maximum gas rate (m3/hr) 2.12 2.64 3.17 DHW maximum gas rate (m3/hr) 2.96 3.38 3.81 Minimum gas rate (m3/hr) 0.63 0.74 0.74 Injector size (mm) 6.7 6.7 7.0

2.4 Expansion Vessel Unica 28HE Unica 32HE Unica36HE

Capacity 8-litres 10-litres 10-litres Maximum system volume 76-litres 91-litres 91-litres Pre-charge pressure 1.0 bar

2.5 Dimensions Unica 28HE Unica 32HE Unica36HE

Height (mm) 780 780 780 Width (mm) 400 450 450 Depth (mm) 358 358 358 Dry weight (kg) 40 42 45

2.6 Clearances UNICA HE Range

Sides 12mm Top 150mm from casing or 25mm above flue elbow (whichever is applicable) Bottom 150mm Front 600mm

2.7 Connections UNICA HE Range

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

2.8 Electrical Unica 28HE Unica 32HE Unica36HE

Power consumption (Watts) 150W 150W 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 28HE Unica 32HE Unica36HE

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

2.9A Flue Details (twin pipes) Unica 28HE Unica 32HE Unica36HE

Maximum horizontal flue length (80mm/80mm) 40m/40m 35m/35m 35m/35m Maximum vertical flue length (80mm/80mm) 40m/40m 35m/35m 35m/35m

2.10 Efficiency Unica 28HE Unica 32HE Unica36HE SEDBUK (%) 90.3 90.2 90.1

2.11 Emissions Unica 28HE Unica 32HE Unica36HE

CO2 @ maximum output (%) 9.0 9.0 9.0 CO2 @ minimum output (%) 9.0 9.0 9.0 CO/CO2 ratio @ maximum output 0.002 to 1 0.002 to 1 0.002 to 1 CO/CO2 ratio @ minimum output 0.0004 to 1 0.0004 to 1 0.0004 to 1 CO @ maximum output (mg/kWh) 182.8 215.0 215.0 CO @ minimum output (mg/kWh) 53.8 32.3 32.3 NOx @ maximum output mg/kWh) 105.9 105.9 88.3 NOx @ minimum output (mg/kWh) 61.8 61.8 70.6 NOx rating class 5 class 5 class 5

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 H From internal/external corner or boundary 300 mm

I Above ground, roof, or balcony level 300 mm J From a surface or boundary facing the terminal 1200 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 500 mm

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

of the vertical terminal

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

the appliance gas inlet connection must not be used. The installation must be tested for soundness 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.

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.

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

It should be in accordance also with any relevant requirements of the local authority and the relevant recommendations of the following British Standard

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).

Codes of Practice.

In cold and/or humid weather, water vapour will

3.2 LOCATION OF APPLIANCE

The appliance may be installed in any room or

condense on leaving the terminal; the effect of such pluming must be considered.

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

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

internal space containing a bath or shower.

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

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, 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. This appliance is not suitable for external installation.

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

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, 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.

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 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. ). 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.

control

fig.5

flow/return

pipe

valve

temporary

connection

double

check valve

control

valve

supply

pipe

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 feed 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

appliance 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.

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.

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.3 GAS SUPPLY

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 soundness 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

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 EXPANSION VESSEL

3A.6.6 FILLING POINT

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.

3A.6.7 LOW PRESSURE SEALED SYSTEM

3A.6.8 FREQUENT FILLING

3A.7 ELECTRICAL SUPPLY

,5 mm (3° high-voltage

category). The switch must only supply the

appliance and its corresponding controls, i.e. time clock, room thermostat, etc.

fig. 6

115

114

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.

fig. 7

Hot water

outlet

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. 8

C/H flow

valve

C/H return

valve

Gas

cock

Cold water inlet

stopcock/filling

valve

Filling loop

Safety valve outlet

Default screws position of fixing jig: No. 3

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.

4.2 CONTENTS

Contained within the carton is:

• The boiler

• The wall bracket & fixing jig

• Template

• An accessories pack containing appliance

service 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.

4.4 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).

horizontal plane (see 2.9). A reduction must also be made to the maximum length (see table below) when additional bends are used.

Reduction for additional bends Bend Reduction in maximum flue length for

each bend 45º bend 0.5 metre 90º bend 1.0 metre

Horizontal flue terminals and accessories

Part No. Description Length

520 Horizontal flue kit 900mm 521 Telescopic flue kit 350/530mm 522 Plume management kit 1370mm 523 90-degree bend N/A 524 45-degree bends (pair) N/A 525 500mm extension 500mm 526 1000mm extension 1000mm 527 2000m extension 2000mm 528 Telescopic extension 350/730mm 529 Wall bracket pack (5) 208mm

Using the template provided, mark and drill a 115mm hole for the passage of the flue pipe. The hole should be drilled to ensure any condense fluid that forms, is allowed to drain back to the appliance (see fig. 9A).

The fixing holes for the wall-mounting bracket/ fixing jig should now be drilled and plugged, an appropriate type and quantity of fixing should be used to ensure that the bracket is mounted securely. Once the bracket has been secured to the wall, mount the appliance onto the bracket.

4.5 FITTING THE FLUE

The top flue outlet permits both horizontal and vertical flue applications to be considered, alternatively, the Vokera twin flue system can be utilised if longer flue runs are required.

4.5.1 CONCENTRIC HORIZONTAL FLUE

(For concentric vertical flue, see 4.5.2) (For twin flue applications, see 4.5.3) The appliance can be used with either the Vokera condensing 60/100mm concentric flue system or the optional 80/125mm concentric flue system.

NOTE

These instructions relate only to the Vokera condensing 60/100mm concentric flue system. For specific details on the installation of the 80/ 125mm concentric flue system please refer to the instructions supplied.

The appliance flue outlet elbow can be rotated through 360º on its vertical axis. In addition the flue may be extended from the outlet elbow in the

Fig. 9

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vokera Unica 28 HE User guide

Specifications and Main Features

Frequently Asked Questions

User Manual