Wessex 220 M Series Instruction Manual

IMPORTANT NOTE
THESE INSTRUCTIONS MUST BE READ
AND UNDERSTOOD BEFORE INSTALLING,
COMMISSIONING, OPERATING OR
SERVICING EQUIPMENT

Technical Enquiries 01202 662527/662528
To supplement the detailed technical brochures, technical advice on the application and use of products in the
Hamworthy Heating range is available from our technical team in Poole and our accredited agents.
Site Assembly 01202 662555
Hamworthy offer a service of site assembly for many of our products in instances where plant room area is restricted.
Using our trained staff we offer a higher quality of build and assurance of a boiler built and tested by the manufacturer.
Commissioning 01202 662555
Commissioning of equipment by our own engineers, accredited agents or specialist sub – contractors will ensure the
equipment is operating safely and efficiently.
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Regular routine servicing of equipment by Hamworthy service engineers inspects the safety and integrity of the plant,
reducing the risk of failure and improving performance and efficiency. Maintenance agreements enable our customers to
plan and budget more efficiently.
Breakdown service, repair, replacement 01202 662555
Hamworthy provide a rapid response breakdown, repair or replacement service through head office at Poole and accred-
ited agents throughout the UK.
Spare Parts 01202 662525
A comprehensive spare parts service is operated from our factory in Poole, providing replacement parts for both current
and discontinued products. Delivery of parts and components is normally from stock within seven days. However, a next
day delivery service is available for breakdowns and emergencies.
Customer Services

HAMWORTHY HEATING LTD
WESSEX 220 M 500001110/E
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NOTE: THESE INSTRUCTIONS MUST BE READ AND UNDERSTOOD BEFORE
INSTALLING, COMMISSIONING, OPERATING OR SERVICING EQUIPMENT.
THE WESSEX 220 M BOILER IS INTENDED FOR USE AS A COMMERCIAL APPLIANCE.
THIS BOILER IS FOR USE ON GROUP H NATURAL GAS (2ND FAMILY) I2H OR LPG-
PROPANE (3RD FAMILY) I3P. PLEASE ENSURE RELEVANT INFORMATION REQUIRED
WITHIN DOCUMENT IS FOUND RELATING TO SPECIFIC GAS TO BE FIRED BEFORE
FIRING BOILER.
THIS BOILER COMPLIES WITH ALL RELEVANT EUROPEAN DIRECTIVES.
EC TYPE CERTIFICATE Nos. (GAD) EC-87/02/28, (BED) BE-87/02/06.
PRODUCT IDENTIFICATION No. 87BN28.
PUBLICATION NO. 500001110
ISSUE ‘E’
MAY 2006
Wessex 220 M Series Boilers
High Efficiency, Fully Modulating, Pre-Mix, Gas
Fired, Modular Boilers for Heating and Domestic
Hot Water Installations
Installation, Commissioning
and Servicing Instructions
Wessex 220 M220, M440 & M660 Models
NATURAL GAS
I
2H
LPG-PROPANE
I
3P

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CONTENTS
PAGE
1.0 INTRODUCTION.................................................................................................................................1
2.0 TECHNICAL DATA.............................................................................................................................4
3.0 GENERAL REQUIREMENTS.............................................................................................................5
3.1 Related Documents
3.2 Feed Water Quality
3.3 Adequate Water Flow
3.4 Time Clock Control
3.5 Minimum System Water Pressure
4.0 LOCATION..........................................................................................................................................6
5.0 GAS SUPPLY.....................................................................................................................................6
5.1 Service Pipes
5.2 Meters
5.3 Gas Supply Pipes
5.4 Boosted Supplies
5.5 Boiler House Control Valve
5.6 Boiler Gas System Leak Check
6.0 FLUE SYSTEM...................................................................................................................................7
6.1 Flue System General Requirements
6.2 Design Waste Gas Volume and Temperature
6.3 Materials
6.4 Suction
6.5 Disconnection
6.6 Flue Discharge
6.7 Surface Temperatures
6.8 Flue System Location
6.9 Condensate Discharge
7.0 AIR SUPPLY.......................................................................................................................................8
7.1 Air Supply By Natural Ventilation
7.2 Air Supply By Mechanical Ventilation
8.0 WATER CIRCULATION SYSTEM .....................................................................................................9
8.1 General
8.2 Pressure Relief Valve (Safety Valve)
8.3 Open Vent and Cold Feed Pipe
8.4 Altitude Gauge (Water Pressure Gauge)
8.5 Thermometer
8.6 Drain Valves
8.7 Circulating Pump
8.8 Minimum Water Flow Rates
8.9 Waterside Pressure Drop
8.10 Control Schemes
8.11 Unvented Systems
8.12 Modular Boiler Control Schemes

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PAGE
9.0 ELECTRICAL SUPPLY....................................................................................................................11
9.1 Site Wiring
9.2 Indication Signals and Volt Free Contacts
9.3 Sequencing Interface Module (Optional)
10.0 BOILER ASSEMBLY AND INSTALLATION ...................................................................................16
10.1 General
10.2 Connection of Boilers to the Flue System
10.3 Water Connections
11.0 COMMISSIONING AND TESTING...................................................................................................16
11.1 Electrical Installation
11.2 Gas Installation
11.3 Water Circulation System
11.4 Commissioning the Boiler
12.0 FAULT FINDING...............................................................................................................................20
12.1 Safety Features Summary
12.2 Fault Finding Procedures
12.3 Possible Causes of Boiler Lockout
13.0 SERVICING.......................................................................................................................................24
14.0 REPLACEMENT OF FAILED COMPONENTS................................................................................26
15.0 RECOMMENDED SPARES .............................................................................................................29
APPENDIX ‘A’ – INFORMATION RELATING TO PROPANE FIRING................................................................30
FIGURES PAGE
Figure 1.1 Schematic Layout of Typical Boiler Installations.................................................................................2
Figure 2.1 Boiler Dimensions & Clearances.........................................................................................................3
Figure 2.2 Performance & General Data Information – Natural Gas ...................................................................4
Figure 5.1 Gas Valve & Pipework Leak Test Procedure......................................................................................7
Figure 7.1 Mechanical Ventilation Flow Rates.....................................................................................................9
Figure 8.3 Cold Feed and Vent Pipe Sizes..........................................................................................................9
Figure 8.10 Temperature Controls and Boiler On/Off Switch...............................................................................10
Figure 8.12 Site Wiring Diagram .....................................................................................................................13/14
Figure 9.1 Wiring Schematic ..............................................................................................................................15
Figure 9.1.1 Site Wiring Connections—Control Panel Layout ..............................................................................12
Figure 11.1 General Layout of Boiler ...................................................................................................................19
Figure 12.1 Fault Finding Procedures..................................................................................................................21
Figure 12.2 Fault Finding Procedures..................................................................................................................22
Figure 12.3 Fault Finding Procedures..................................................................................................................23
Figure 13.2 Diagram of Hot Surface Igniter and Flame Sensing Probe...............................................................25
Figure 2.2 Performance & General Data Information – LPG Propane...............................................................30

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WESSEX 220 M 500001110/E
1.0 INTRODUCTION
1.1 This boiler must be installed by a competent person
holding 'CORGI' registration or equivalent. All
installations MUST conform to the relevant Gas Safety
and Building Regulations. Health & Safety
requirements must also be taken into account when
installing any equipment. Failure to comply with the
above may lead to prosecution.
1.2 This boiler is intended for use on Group H Natural
Gas (2nd Family) and LPG-Propane (3rd Family). The
information relating to propane firing is to be found in
Appendix ‘A’. Boilers MUST NOT use gas other than
that for which they are designed and adjusted.
1.3 The Wessex 220 M is a gas fired, fully modulating,
fan assisted, open flued central heating / hot water
boiler. Using the latest gas / air ratio control technology
it is able to provide clean efficient operation across a
large output range. The boiler can be supplied in a
modular format, a maximum of three vertically stacked
modules being arranged into a single unit sharing a
common flue
1.3.1 Each boiler module utilises a metal fibre, fan
assisted, pre-mix burner. Operation is initiated by a full
sequence ignition control that incorporates a Hot
Surface Ignition system and rectification supervision of
the flame.
1.3.2 Each of the boiler models is designed for direct
connection to a flue system. The Technical Data for the
various arrangements is given in Section 2. The flue
outlets from more than one unit may be connected to a
single chimney. No draught diverter is fitted to the boiler
nor is a fixed diverter required in the flue system.
However a draught stabiliser is recommended for some
installations.
1.3.3 The Wessex 220 M is floor mounted and is
intended for the heating of Commercial and Industrial
premises. It may also be used to supply hot water for
these premises via an indirect cylinder.
1.3.4 The Wessex 220 M has a low water content and
water flow rates MUST be maintained at or above the
recommended levels shown in Section 8 and Figure
2.2.
1.4 If the boiler is to be connected to an un-vented
(pressurised) heating system, care must be taken to
ensure all extra safety requirements are satisfied and
that the relevant interlocks will shut the boiler(s) off
should a high or low pressure fault occur.
The pressurisation unit must also incorporate a low level
water switch which protects the water pumps and will
directly or indirectly shut down the boiler plant should a
low water condition occur. Consideration should also
be given to the maximum working pressure of the boiler
as given in Section 2: TECHNICAL DATA. Consult
Hamworthy Heating Technical Department for help or
assistance if in doubt.
1.5 The Wessex 220 M boiler is not suitable for direct
connection to domestic hot water supplies.
1.6 The Wessex 220 M boiler can be installed with
either reverse return water flow, (optional kits available)
or with single pipe headers, (non HHL supply).See
Figure 1.1. for typical schematic layout.
BOILER VARIATIONS
Wessex 220 M220 - Single 220 kW unit.
Wessex 220 M440 - Single 440 kW unit created by
stacking 2 – 220 kW modules vertically.
Wessex 220 M660 - Single 660 kW unit created by
stacking 3 – 220 kW modules vertically.
1.7 The fully assembled unit is supplied covered with a
protective sleeve. The flue assemblies for the M440 and
M660 models are supplied in a separate pack.
1.8 Options
1.8.1 Optional reverse return header kits are available
for models M440 and M660. These kits are free-
standing allowing installation to the system prior to
installing the boiler and can incorporate all necessary
valves, inter connecting pipework, and flexible flow and
return connections. Refer to individual kit instructions for
details.
1.8.2 Milton boiler sequence control system for timed
remote control of single and multiple modulating boilers,
with outside temperature compensation and optimised
start. Refer to Milton kit instructions for details.
1.8.3 Sequencing Interface Module – Hamworthy
Heating can supply an interface module fitted within the
boiler module control panel to enable the remote fully
modulating control of the boiler module via a 0-10V
analogue control signal from a non-HHL control system.
An interface module will be required for each boiler
module, and a 0-10V control signal will be required for
each boiler module. Refer to sections 8.12 and 9.3 for
further details.

HAMWORTHY HEATING LTD
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WESSEX 220 M 500001110/E
Figure 1.1 Boiler Installation (Typical)

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WESSEX 220 M 500001110/E
Figure 2.1 Boiler Dimensions/Clearances

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WESSEX 220 M 500001110/E
2.0 TECHNICAL DATA
2.1 The Wessex 220 M boilers can be installed as
single units or in modular form. Each module has an
independent door for access to the controls and other
working components.
Overall dimensions are shown in Figure 2.1. For both
single and multiple boiler arrangements.
It is recommended that a maximum of 2 boilers can be
positioned on 750mm centres if required, Larger
numbers should be split into banks with adequate
access to the rear of each boiler.
2.2 General Information and Technical Data relating to
Natural Gas is shown in Figure 2.2.
Technical data relating to propane firing can be found in
Appendix ‘A’.
2.3 Screw threads: All screw threads used in the
Wessex 220 M boiler conform to the following:-
ISO 7/1 or ISO 228/1 for pipe threads where applicable.
ISO 262 for all general screw threads.
Figure 2.2 Performance and General Data Information – Natural Gas
GENERAL DATA
Wessex 220 M series BOILER MODEL
M220 M440 M660
Boiler Input (maximum) - kW (Gross) 262.22 524.44 786.66
Boiler Input (maximum) - kW (Nett) 236.13 472.26 708.39
Boiler Output kW (maximum) - kW 220 440 660
Boiler Module Output (minimum) - kW 44
FLUE DATA
Nominal Flue Diameter - mm 153 (6”) 254 (10”) 305 (12”)
Approx. Flue Gas Temperature - °C (Gross) 135
Approx. Flue Gas Volume @ 8.7 – 9.3% CO2- m3/h* 329 659 988
GAS DATA
Gas Inlet Connection Pipe Thread Size R1
Nominal Gas Inlet Pressure - mbar 20
Maximum Gas Inlet Pressure - mbar 25
Gas Supply Pressure Switch Setting - mbar
Gas Flow Rate (maximum) - m3/h 24.99 49.97 74.96
Gas Valve Offset Pressure Setting - mbar 0.00
WATER DATA
Water Connections (Flow & Return) G2½ male
Maximum Water Pressure - bar g 10
Water Content (not including headers) - litres 17 34 51
System Design Flow Rate @ 11°C ΔT Rise - litre/s 4.78 9.56 14.33
Minimum Flow Rate @ 15°C ΔT Rise - litre/s 3.50 7.01 10.51
Waterside Pressure Loss @ 11°C ΔT Rise - mbar 64.0
Waterside Pressure Loss @ 15°C ΔT Rise - mbar 34.5
PHYSICAL DATA
Shipping Weight (excluding flue headers) - kg 220 430 635
ELECTRICAL DATA
Normal Supply Voltage 230V ~ 50Hz
Power Consumption (maximum) - W 250 500 750
Start and Run Current (per module) - A 1.07
12.5
* Note:- Flue gas volumes are corrected to a flue gas temperature of 15°C and barometric pressure of
1013.25mbar.