Glowworm Micron 40FF User manual

Hepworth Heating Ltd.,
Nottingham Road, Belper, Derbyshire. DE56 1JT
General/Sales enquiries:
Tel: [phone] Fax: [phone]
One Contact Local Service
Customer Services:
Tel: [phone]
Fax: [phone]
221899A.03.01
All replacement parts
All labour charges
All call-out charges
Thank you for installing a new Glow-worm appliance in your home.
Glow-worm appliances' are manufactured to the very highest standard so we are pleased
to offer our customers' a Comprehensive First Year Guarantee.
In the centre pages are to be found your Guarantee Registration Card, which we recommend you complete and
return as soon as possible.
If this card is missing you can obtain a copy or record your registration by telephoning the Heatcall Customer
Service number 01773 828100.
Our Guarantee gives you peace of mind plus valuable protection against breakdown by covering the cost of:
Guarantee Registration
Fanned Flue Boiler
This is a Cat I2H Appliance
Reference in these instructions to British Standards and Statutory
Regulations/Requirements apply only to the United Kingdom.
For Ireland the rules in force must be used.
The instructions consist of three parts, User, Installation and Servicing Instructions, which includes the Guarantee Registration
Card. The instructions are an integral part of the appliance and must, to comply with the current issue of the Gas Safety
(Installation and Use) Regulations, be handed to the user on completion of the installation.
Tobeleftwiththeuser
7319
❏
✔
❏
✔
❏
✔
Instructions for Use
Installation and Servicing
G.C. No. 41-047-17
REGISTER YOUR GLOW-WORM APPLIANCE
FOR 1ST YEAR GUARANTEE PROTECTION
CALL 0208 247 9857
Micron
40FF

2
221899A
Important Information
General Information 3
Lighting the Boiler 3
General Data 1 4
Flue and Ventilation 2 6
Water Systems 3 7
Flue and Appliance Preparation 4 9
Boiler Installation 5 12
Commissioning 6 16
Instructions to the User 7 17
Servicing 8 18
Fault Finding 9 19
Replacement Parts 10 22
Spare Parts 11 24
CONTENTS DESCRIPTION SECTION PAGE No.
INSTRUCTIONS
FOR USE
INSTALLATION
INSTRUCTIONS
SERVICING
INSTRUCTIONS
TESTING AND CERTIFICATION
This boiler is tested and certificated to EN483 for safety and performance. It is therefore important that no alteration is made to the
boiler, without permission, in writing, from Hepworth Heating Ltd.
Any alteration not approved by Hepworth Heating Ltd., could invalidate the certification, boiler warranty and may also infringe the
current issue of the Statutory Requirements.
CE MARK
This boiler meets the requirements of Statutory Instrument No. 3083 The boiler (Efficiency) Regulations, and therefore is deemed
tomeettherequirementsofDirective92/42/EEContheefficiencyrequirementsfornewhotwaterboilersfiredwithliquidorgaseous
fuels.
Type test for purposes of Regulation 5 certified by: Notified body 0086.
Product/productioncertifiedby: Notified body 0086.
The CE mark on this appliance shows compliance with:
1.Directive 90/396/EECon theapproximation ofthe Lawsof theMember Statesrelating toappliances burninggaseous fuels.
2. Directive 73/23/EEC on the harmonization of the Laws of the Member States relating to the electrical equipment designed
for use within certain voltage limits.
3. Directive 89/336/EEC on the approximation of the Laws of the Member States relating to electromagnetic compatibility.
INFORMATION FOR THE INSTALLER AND SERVICE ENGINEER.
Under Section 6 of The Health and Safety at Work Act 1974, we are required to provide information on substances hazardous to
health.
Insulation pads and Glass yarn.
These can cause irritation to skin, eyes and the respiratory tract. If you have a history of skin complaint you may be susceptible to
irritation. High dust levels are usual only if the material is broken. Normal handling should not cause discomfort, but follow normal
good hygiene and wash your hands before eating, drinking or going to the lavatory. If you do suffer irritation of the eyes or severe
irritation to the skin seek medical attention.
SPARE PARTS
REMEMBER, When replacing a part on this appliance, use only spare parts that you can be assured conform to the safety and
performancespecificationthatwerequire. DonotusereconditionedorcopypartsthathavenotbeenclearlyauthorisedbyHepworth
Heating Ltd.

3221899A
Introduction
Pleasereadtheseinstructionsand followthemcarefullyforthe
safe and economical use of your boiler.
The Micron series are fanned flue boilers designed to provide
central heating and indirect domestic hot water.
The boiler is fully automatic in operation having only one user
control, the temperature control.
WARNING. It is important that the case is not disturbed or
removed other than for servicing by a competent person.
Gas Leak or Fault
If a gas leak or fault exists or is suspected, the boiler must be
turned off, including the electrical supply and must not be used
until the fault has been put right.
Advice/helpshouldbeobtainedfromyourinstallation/servicing
company or the local gas undertaking.
Electrical Supply Failure
Failure of the electrical supply will cause the burner to go out.
Should this occur, operation of the appliance will normally
resume after the electrical supply is restored.
Note: If the boiler is switched OFF, manually, wait at least 30
seconds before switching on again.
Safety Temperature Limiter
IftheoverheatSafetyTemperatureLimiteroperatesasindicated
by illuminated reset light, open the controls cover and turn
temperature control to “0” (anticlockwise) and then back to
original position, refer to diagram 9.1. If the overheat operates
again, turn the appliance off and contact your installation/
servicing company.
Protection Against Freezing.
If the boiler is to be out of use for any long period of time during
severeweatherconditionswerecommendthatthewholeofthe
system, including the boiler, be drained off to avoid the risk of
freezingup. Makesurethat,iffitted,theimmersionheaterinthe
cylinder is switched off. Alternatively, there is a built-in frost
protection which will cause the boiler when it is switched off at
thecontrolknobtooperateintheeventofthewatertemperature
in the boiler dropping to 6oC or 7oC. The boiler will switch off
again when the temperature of the water in the boiler reaches
about 15oC. This will only be fully effective if the external
controlsaresetsothatthepumprunscontinuously,thatisthey
are calling for heat.
Note:Thefrostprotectionwillnotoperateiftheelectricalsupply
is turned off.
Maintenance
To ensure the continued efficient and safe operation of the
boiler it is recommended that it is checked and serviced as
necessary at regular intervals. The frequency of servicing will
depend upon the particular installation conditions and usage,
but in general once a year should be enough.
If this appliance is installed in a rented property there is a duty
of care imposed on the owner of the property by the current
issue of The Gas Safety (Installation and Use) Regulations,
Section 35.
It is the law that any servicing is carried out by a competent
person.
To obtain service, please call your installer or Heatcall (Glow-
worm’sownServiceOrganisation)usingthetelephonenumber
given on the front cover of these instructions.
Please be advised that the ‘Benchmark’ logbook should be
completed by the installation engineer on completion of
commissioning and servicing.
Instructions for Use
All CORGI Registered Installers carry a CORGI ID card, and
have a registration number. Both should be recorded in your
boilerLogbook. YoucancheckyourinstallerisCORGIregistered
by calling CORGI direct on :- 01256 372300.
Cleaning
WARNING. Thisappliancecontainsmetalparts(components)
and care should be taken when handling and cleaning, with
particular regard to edges.
Clean the casing occasionally by wiping it over with a damp
cloth or dry polishing duster.
Do not use an abrasive cleaner.
To Light the Boiler
WARNING. Sealed Systems
A sealed water system must be filled and pressurised by a
competent person.
Onlylighttheboilerwhenyouaresurethatthesystemhasbeen
filled and pressurised.
Thepressure gauge shouldshowat least 0.7bar,anythingless
thanthisfigurecouldindicatealeakandyouMUSTcontactyour
installation/servicing company.
If there is any doubt about the boiler being full of water consult
your installation/servicing company.
ALL SYSTEMS.
Turn the electrical supply on to the boiler and check that all
remote controls are calling for heat. Check also that the
programmer (if fitted) is in the “ON” mode.
To Turn the Boiler On
Open the controls cover, see diagram 9.1.
Turnthecontrolknobclockwisetoanypositionbetween“0” and
MAX. Themaximumtemperaturesettingisabout82oC(180oF),
see diagram 9.1.
The boiler lighting operation is now automatic as follows:
The fan operates and after a short period of time, the spark
ignition operates, the solenoid opens, then the burner will light
shownbythe“BurnerOn”neononthecontrolpanellightingup.
The burner will remain alight until switched off by the control
thermostat, any remote control or the programmer.
Note: If the boiler is switched OFF, by hand, wait at least 30
seconds before switching on again.
When the boiler switches off, the burner will go out.
The automatic lighting sequence will operate again when heat
is required.
Shut the controls cover.
To Turn the Boiler Off
Forshortperiods,turnthecontrolknobanti-clockwiseto“0”Off.
Torelight,turnthecontrolknobtoanypositionbetween“0”and
“MAX”.
For longer periods, turn the control knob fully anti-clockwise to
“0” Off and switch off the electrical supply to the boiler.
To relight follow the lighting sequence given above.
Optional Programmer
Aprogrammerisavailable,whichwillautomatically switch your
central heating system on and off once or twice a day at
whatever times you choose.

4
221899A
Installation - 1 General
Important Notice
This boiler is for use on natural gas (G20) as distributed in the
United Kingdom and Ireland and cannot be used on any other
gas.
Thisboilercanbeusedonopenventedorsealedwatersystems.
Domestic hot water must be provided by pumped circulation.
Wherever possible, all materials, appliances and components
used shall comply with the requirements of applicable British
Standards.
Where no British Standards exists, materials and equipment
should be fit for their purpose and of suitable quality and
workmanship.
Sheet Metal Parts
WARNING. When installing or servicing this boiler care should
betakenwhenhandlingsheetmetalparts,toavoidanypossibility
of personal injury.
1.1 Statutory Requirements
The installation of the boiler must be carried out by a CORGI
registeredinstallerinaccordancewiththerelevantrequirements
of the current issue of:
The manufacturer’s instructions supplied.
TheGasSafety(Installationand Use) Regulations,TheBuilding
Regulations, The Building Standards (Scotland) Regulations
(applicable in Scotland), Local Water Company Bye-laws,
The Health and Safety at Work Act, Control of Substances
Hazardous to Health (COSHH), The Electricity at Work
Regulations and any local regulations which may apply.
Detailed recommendations are contained in the current issue of
the following British Standards and Codes of Practice:
BS4814,BS6798,BS5440Part1and2,BS5546 Part1,BS5449,
BS6891, BS6700, BS7074 Part 1 and 2, BS7593, BS7671.
Manufacturer’s instructions must not be taken as overriding
statutory requirements.
1.2 Data
See Table 1 and diagrams 1.1 and 1.2.
All dimensions are given in millimetres (except as noted).
The Seasonal Efficiency Domestic Boilers UK (SEDBUK) is
77.3%.
ThevalueisusedintheUKGovernment’sStandardAssessment
Procedure (SAP) for energy rating of dwellings. The test data
from which it has been calculated have been certified by B.S.I.
1.3 Range Rating
This boiler is range rated and may be adjusted to suit individual
systemrequirements,refertodiagram1.2fordatalabelposition,
ratings and settings.
1.4 Heating System Controls
The heating system should have installed: a programmer and
room thermostat controlling the boiler.
Thermostatic radiator valves may be installed in addition to the
room thermostat.
Note: For further information, see The Building Regulations
1991- Conservation offueland power,1995edition - Appendix
G, table 4b.
Anoptionalprogrammerforfittingontheboilerisavailble,kitno.
458065.
1.5 Gas Supply
Thegasinstallationshallbeinaccordancewiththecurrentissue
of BS6891. The supply from the governed meter must be of
adequate size to provide a steady inlet working pressure of
20mbar (8in wg) at the boiler.
On completion test the gas installation for soundness using the
pressure drop method, purge in accordance with the above
standard.
1.6 Electrical Supply
WARNING. This boiler must be earthed.
All system components shall be of an approved type and shall
be connected in accordance with the current issue of BS7671
and any applicable local regulations.
All external wiring between the appliance and the electrical
supply and earthing requirements shall comply with the current
IEE Regulations.
Connectionoftheboilerandsystemcontrolstothemainssupply
must be through a common isolator and must be fused 3A,
maximum. This method of connection must be by a fused
doublepoleisolatingswitch,withaminimumcontactseparation
of3mm onboth poles. Theswitch should bereadily accessible
and preferably adjacent to the appliance. It should supply the
appliance only and be easily identifiable as so doing.
Diagram 1.1
All dimensions are given in millimetres
AB
C
D
E
M
FG
PUMPED
RETURN
PUMPED
FLOW
C
WATER CONNECTIONS
22mm COPPER PIPE
GAS CONNECTION
RC 1/2(1/2in. BSPT)
6784
L
H
J
K
P
N
Q
TOP / SIDE
FLUE OPTION
REAR
FLUE OPTION
R
MODEL A B C D E F G H J K L M N P Q R
40FF 262 75 102 360 139 500 68 85 115 115 126 156 100 104 4 40 68 108
STD/EXD. EASYFIT STD/EXD. EASYFIT

5221899A
FRONT
VIEW
2mm 2mm
*
6mm
10mm FROM A NON-PERMANENT
300mm FROM A PERMANENT
6mm 6mm
50mm
Diagram 1.3
1.12 Boiler Clearances
Refer to diagram 1.3.
This boiler must be positioned so that at least the minimum
operational and servicing clearances are provided.
Additional clearances may be required for installation.
If fixtures are positioned next to the boiler ensure access is
provided for pipework installation.
At least a minimum clearance of 300mm from a permanently
fixed surface must be left in front of the boiler for servicing, see
diagram 1.3.
1.13 Room Ventilation
The boiler is room sealed and does not require the room or
space containing it to have permanent air vents.
7064
1 General
Alternatively, an unswitched shuttered socket outlet and 3A
fused 3 pin plug, both to the current issue of BS1363 may be
usedprovidedthattheyarenotusedinaroomcontainingabath
or shower.
WiringtotheboilermustbePVC 850C insulated cable,notless
than 0.75mm2(24/0.20mm).
1.7 Contents of Packaging
Theboilerisdeliveredinone packwiththe fluesystempacked
separately.
1.8 Water System
This boiler may be fitted to an open vented or a sealed water
system.
1.9 Draining Tap
System
A draining tap must be provided at the lowest points of the
systemwhichwillallowtheentiresystemandhotwatercylinder
to be drained.
Draining taps should be to the current issue of BS2879.
Boiler
Adrainingpointisfittedatthebottomrighthandsideoftheheat
exchanger.
When draining is required cover the controls to avoid water
damage.
If required remove the combustion chamber front cover to
improve access.
1.10 Safety Valve
A safety valve need not be fitted to an open vented system.
1.11 Location
This boiler is not suitable for outdoor installation.
This boiler may be installed in any room, although particular
attention is drawn to the requirements of the current issue of
BS7671 with respect to the installation of a boiler in a room
containing a bath or shower. Any electrical switch or boiler
control utilising mains electricity should be placed so that it
cannot be touched by a person using the bath or shower.
The electrical provisions of the Building Standards (Scotland)
apply to such installations in Scotland.
The boiler must be mounted on a flat wall which is sufficiently
robust to take its total weight.
Theboilermaybefittedtoawallmadeofcombustiblematerial. Diagram 1.2
7262
HEPWORTH HEATINGLTD.,
BELPER,DERBYS.DE561JT
MICRON 40FF
458111
SERIALNo.
GCNo. 41-047-17
0086
86/AU/000
GB IE
230V 50Hz 66W Fused at 3A
For use on G20 gas only
Supply pressure 20 mbar
This boiler is intended exclusively
to be installed on a gas supply
withagovernedmeter
~
RANGERATING MIN MID MAX
HEAT
INPUT NETT kW
kW
Btu/h
Btu/h
HEAT
OUTPUT
HOT BURNER
PRESSURE mbar
in wg 5.7
14.3
40000
44493
13.04
11.50
4.4
11.0
35000
10.26
39222
9.95
3.1
7.8
30000
8.79
33957 11.72
INJECTOR:3.0mm 205757
Cat.
EN437
I2H
TYPE C C PMS= 3.0 bar
Q=
P=
NO Class 2
x
32,12,
C
52
PMS = 3.0 bar, is: Maximum water-side operating pressure.
The appliance flue type is a C12, C32 and C52. This refers to a
concentric or twin flue where the fan is downstream of the heat
exchanger. The C12 is a horizontal flue termination, the C32 is a
vertical flue termination and the C52 has seperate ducts to two
terminals that may terminate in zones of different pressure.
DATA
LABEL
7316
190mm with Easyfit top flue fitted,
160mm with standard/extended top flue fitted,
20mm without top flue fitted
Increased top clearance is required if flow pipe enters from
below to permit access to air vent.
MINIMUM CLEARANCES FROM WALLS, CEILING, FLOOR,
CUPBOARD, WORKTOPS AND INFLAMMABLE MATERIALS
*
*

6
221899A
1.14 Boilers in a Compartment
Wherethe installationof theboilerwill bein anunusual position,
the current issue of BS6798 gives detailed guidance on these
requirements.
An existing cupboard or compartment modified for the purpose
may be used, providing minimum clearances are maintained.
Details of essential requirements for cupboard or compartment
design are given in the current issue of BS6798.
Thedoorwayopeningshouldbeofsufficientsizetoallowforeasy
removal of the boiler.
Wheretheboilerisfittedinacupboardorcompartment,permanent
ventilation is not required.
1.15 Timber Frame Building
IIf the boiler is to be installed in a timber frame building it should
be fitted in accordance with the Institute of Gas Engineers
documentIGE/UP/7/1998. Ifindoubt seekadvicefromthelocal
gas undertaking or Hepworth Heating Ltd.
TABLE 1.
TOTAL DRY WEIGHT
(Including Terminal)
LIFT WEIGHT
WATER CONTENT
GAS CONNECTION
ELECTRICITY RATING
WATER CONNECTION
ELECTRICITY SUPPLY
DATA LABEL
36.4 kg (80lb)
29.7 kg (65.34lb)
2.2 litre (0.48 gallon)
Rc 1/2in.
66W Internal fuse Type F4A
2x22mm copper pipes from
back of case
230V~50Hz,fused 3A
Top left hand inside of case
The flue must be installed in accordance with the rules in force
in the countries of destination.
2.1 Terminal Position
The minimum acceptable siting dimensions for the terminal
fromobstructions, other terminalsandventilation openingsare
shown in diagram 2.1.
The terminal must be exposed to the external air, the position
allowing free passage of air across it at all times.
Car ports or similar extensions of a roof only, or a roof and one
wall,requirespecialconsiderationwithrespecttoanyopenings,
doors, vents or windows under the roof. Care is required to
protect the roof if it is made of plastic sheeting. If the car port
consists of a roof and two or more walls, seek advice from the
local gas company before installing the boiler.
If the terminal is fitted within 600mm below plastic guttering or
paintedsoffitanaluminiumshield1500mmlongshouldbefitted
immediately beneath the guttering or eaves. If the terminal is
fittedwithin450mmbelowpaintedeavesorapaintedgutter,an
aluminium shield 750mm long should be fitted immediately
beneath the guttering or eaves.
2.2 Flue Options
There are various flue systems to choose from, as follows:
Standard Top Outlet Flue Pack - Pt.No. 230483
Easyfit Top Outlet Flue Pack - Pt. No. 232057
Standard Rear Outlet Flue Pack - Pt. No. 230482
Extended Top Outlet Flue Pack - Pt. No. 230487
1 Metre Extension Kit - Pt. No. 230484
A flue system up to 3 metres in length can be made by
connecting 1 metre flue extension kits together.
Optional Wall Liner Kit No. 900862
A Flue Bend Kit or Vertical Flue Kit up to 4 metres can be
supplied, see Hepworth Heating "Flue Options Guide" for
configurations available.
45oFlue Bend Pack - Pt. No. 230485
90oFlue Bend Pack - Pt. No. 230486
In Line Flue Adapter Kit - Pt. No. 230488
Vertical Flue Kit No. 458115
1 General
2 Flue andVentilation
Diagram 2.1
0103M
A
A
FGEA
G
G
G
B,C B,C
FF
K
K
K
C
G
LL
Under Car Port etc.
H,I
JD
F
K
M
MINIMUM SITING DIMENSIONS FOR
FANNED FLUE TERMINALS POSITION
A DIRECTLY BELOW, ABOVE OR HORIZONTALLY
TO AN OPENING, AIR BRICK, OPENING
WINDOWS, AIR VENT OR ANY OTHER
VENTILATION OPENING. 300
B BELOW GUTTER, DRAIN/SOIL PIPE 25
C BELOW EAVES 25
D BELOW A BALCONY OR CAR PORT 25
E FROM VERTICAL DRAIN PIPES AND SOIL PIPES 25
F FROM EXTERNAL CORNERS 25
G ABOVE ADJACENT GROUND OR BALCONY LEVEL 300
H FROM A SURFACE FACING THE TERMINAL 600
I FACING TERMINALS 1200
J FROM OPENING (DOOR/WINDOW) IN
CAR PORT INTO DWELLING 1200
K VERTICAL FROM A TERMINAL 1500
L HORIZONTALLY FROM A TERMINAL 300
M FROM INTERNAL CORNERS 25
MINIMUM
SPACING in mm
1.16 Anti-theft Kits
Anti-theft kits are available for these appliances, contact
Hepworth Heating Ltd. for further information.

7221899A
Diagram 3.1
2.3 Terminal Guard
A terminal guard is required if persons could come into contact
with the terminal or the terminal could be subject to damage.
If a terminal guard is required, it must be positioned to provide
aminimumof50mmclearancefromanypartoftheterminaland
be central over the terminal, see diagram 2.2.
A suitable guard, reference Type “K3”, can be obtained from:
Tower Flue Components Ltd.,
Morley Road, Tonbridge,
Kent. TN9 1RA
Diagram 2.2
7056
Theinstallationoftheboilermustcomplywiththerequirements
of the current issue of BS6798.
3.1 Frost Protection
Thereisabuilt-infroststatinthisboiler.SeeProtectionAgainst
Freezing in Instructions for Use. Where other parts of the
systemarevulnerablethisshouldalsobeconsideredasspecified
in the current issue of BS5422.
3.2 Pump
The pump, with integral valves, should be fitted in the heating
flow pipework from the boiler, it should be set to produce a
temperature difference of 11oC (20oF), between the flow and
return, with the boiler thermostat set at “MAX”, which is about
82oC (180oF).
The pressure loss of the boiler at 15.3 litre/minute giving 11oC
temperature difference is 150mm head of water.
High resistance microbore systems may require a higher duty
pump.
3.3 Bypass
A bypass is unnecessary, unless thermostatic radiator valves
are fitted to all radiators.
Ifrequired,a15mmbypassmustbefittedatleast2mawayfrom
theboilerandadjustedsuchthatthereisatemperaturedifference
no greater than 200C between flow and return.
3.4 Water System
Foranopenvented system theboilermustbesuppliedfrom an
unrestricted water supply taken from a feed and expansion
cisternfittedatamaximumheightof27metresabovetheboiler.
The cold feed must be 15mm minimum size.
It is important that the relative positions of the pump, cold feed
and open vent are as shown in diagram 3.1.
Theunrestrictedopenventfromtheboilermustrisecontinuously
to discharge over the feed and expansion cistern.
3.5 Domestic Hot Water System
General. Thedomestichotwaterservicemustbeinaccordance
withthe currentissueof BS5546,referalso tothecurrent issue
of BS6700.
3.6 Cylinder
Forall systemssupplying domestic hotwater thecylinder must
be indirect. It is recommended that the cylinder be fitted with
some form of temperature control.
3.7 Open Vented Fully Pumped Heating and
Domestic Hot Water
TheconnectionsforthesystemMUSTbeasshownindiagrams
3.1 and 3.2.
3.8 Inhibitor
Attention is drawn to the current issue of BS5449 and BS7593
on the use of inhibitors in central heating systems.
When installing in an existing system take special care to drain
theentiresystem,includingradiators,thenthoroughlycleaning
outbeforeinstallingtheboilerwhetherornotaddinganinhibitor.
2 Flue andVentilation
3Water Systems
7065
FEED AND
EXPANSION
CISTERN
22mm VENT
(MIN.)
15mm (MINIMUM)
COLD FEED
OPEN VENTED FULLY PUMPED WATER SYSTEM
RECOMMENDED RELATIONSHIP BETWEEN
PUMP COLD FEED AND VENT
450mm
MIN.
HEIGHT
1METRE
MIN.
RETURN FLOW
CYLINDER
PUMP
HEATING
150mm
MAX.
BOILER IF REQUIRED
15mm (MINIMUM)
BY-PASS WITH
LOCKSHIELD VALVE
FLOW
RET.
There must
always be a cold
water path to the
return connection
of the boiler.

8
221899A
3Water Systems
3.9 Sealed Water Systems
Theinstallationshouldcomplywiththeappropriaterequirements
of the current issue of BS4814, BS5449, BS6759, BS6798 and
BS7074 Part 1 and 2.
3.10 Safety Valve
A safety valve must be fitted to a sealed water system.
It shall be preset, nonadjustable with a lift pressure of 3bar,
incorporating seating of a resilient material, a test device and a
connection for drain.
The drain from the safety valve must be routed clear of any
electrical fittings and positioned so that any discharge can be
seen.
3.11 Expansion Vessel - Sealed Systems Only
A diaphragm type expansion vessel, conforming to the current
issue of BS4814 (see also BS7074 Part 1 and 2) must be
connected at a point close to the inlet side of the circulating
pump, unless laid down differently by the manufacturer.
The expansion vessel volume depends upon the total water
systemvolume andthe initialsystem designpressure. For any
systeman accuratecalculationof thevessel size isgiven inthe
current issue of BS7074 Part 1.
Example: For an initial system design pressure of 0.7bar the
minimum total vessel volume required is 0.063xTotal System
volume.
Note. A higher initial design pressure requires a larger volume
expansion vessel.
Guidance on vessel sizing is also given in the current issue of
BS5449 and BS7074 Part 1.
Thechargepressuremustnotbelessthanthestaticheadofthe
system, that is, the height of the highest point of the system
above the expansion vessel.
The water content of the boiler is given in Data Table 1.
3.12 Pressure Gauge - Sealed Systems Only
A pressure gauge with a set pointer and covering at least the
rangeof0to4bar(0to60lb/in2)shallbepermanentlyfittedtothe
system in a position where it can be seen when filling the
system.
3.13 Domestic Hot Water Cylinder
SINGLEFEEDINDIRECTCYLINDERSARE NOT SUITABLE.
Thedomestichotwatercylindermustbeoftheindirectcoiltype.
It must be suitable for working at a gauge pressure of 0.35bar
above the safety valve setting.
3.14 Domestic Hot Water System - Unvented
Wherea storagesystem willnot havea ventto atmospherethe
installation must comply with Building Regulations and local
WaterCompanyBye-laws,seealsothecurrentissueofBS6700.
If fitting into an existing system the local authority must also be
advised.
Diagram 3.2
PUMPED
RETURN
PUMPED
FLOW
6770
22mm
PIPE
22mm
PIPE
22mm
PIPE
22mm
PIPE
1metre Min.
27 metres
Max.
INDIRECT
CYLINDER ALTERNATIVE
SYSTEM
CONTROL
VALVES
HEATING
SYSTEM
PUMP
7067
IF REQUIRED
BYPASS 15mm
MIN WITH
LOCKSHIELD
VALVE
1metre Min.
27 metres
Max.
INDIRECT
CYLINDER
ALTERNATIVE
SYSTEM
CONTROL
VALVES
HEATING
SYSTEM
PUMP
IF REQUIRED
BYPASS 15mm
MIN WITH
LOCKSHIELD
VALVE
FULLY PUMPED CIRCULATION
BYPASS (DIAGRAMMATIC)
22mmFORCOMBINEDFEED&VENTTOBEFITTED
IN ACCORDANCE WITH BS5449
FULLY PUMPED CIRCULATION
BYPASS (DIAGRAMMATIC)
22mmVENT&15mmCOLDFEEDTOBEFITTED
IN ACCORDANCE WITH BS5449
3.15 Filling a Sealed Water System
Provision for filling the system at low level must be made.
Theinstallationshouldcomplywiththeappropriaterequirements
of the current issue of BS 5449.
3.16 Water Makeup
Provision must be made for replacing water lost from the
system. A make up vessel mounted above the highest point of
the system and connected through a non-return valve to the
system on the return side of either the hot water cylinder or
heating system.

9221899A
Diagram 4.1
4 Flue and Appliance Preparation
TOP OUTLET/REAR FLUE
TOP OUTLET/SIDE FLUE
15mm
VIEW 'B'
510mm
MAX. 15mm
52mm
VIEW 'A'
VIEW 'A'
SPIGOT
FLUE
Note: Outer casing, mounting brackets & boiler details removed for clarity
REAR OUTLET FLUE PACK
STD/EXTD.TOP OUTLET FLUE PACK
& 1 METRE EXTENSION KIT
SCREW
& TAPE
SCREW
& TAPE
SCREW
& TAPE
FOAM
SEAL
9353
1 metre extension kits
may be joined together,
but the total flue
system must not
exceed 3 metres.
44.5mm*
52mm
FLUE LENGTH
MAX 840mm (extd.)
MAX 570mm (std/Easyfit)
FLUE LENGTH
MAX 840mm (extd.)
MAX 570mm (std/Easyfit)
15mm
SCREW
& TAPE
4mm*
140mm*
TOP OUTLET FLUE PACK
Note: Outer casing, mounting brackets &
boiler details removed for clarity
Note: Outer casing, mounting brackets & boiler details removed for clarity
'X'
STD/EXTD
'X' plus 19mm (RH)
155mm (LH) = flue length
VIEW 'B' 15mm
Total must not exceed 3m MAX.
SCREW
& TAPE
SCREW
& TAPE
STD/EXTD SIDE FLUE
'X' plus 19mm (RH)
155mm (LH) = flue length
EASYFIT
'X' plus 47mm (RH)
'X' plus 183mm (LH) = flue length
STD/EXTD REAR FLUE
'Y' plus 22.5mm = flue length
EASYFIT
'Y' plus 50.5mm = flue length
'Y'
'X'
'Y' plus 67mm
= flue length
'Y'
STD/EXTD
'Y' plus 22.5mm
= flue length
EASYFIT
'Y' plus 50.5mm
= flue length
'Y'
15mm
52mm
'Y' plus 67mm = flue length
'Y'
SCREW
& TAPE
Total must not exceed 2m MAX.
SCREW
& TAPE
STD. REAR OUTLET FLUE PACK
& 1 METRE EXTENSION KIT
FOAM
SEAL
1 metre extension kits may be
joined together, but the total
flue system must not
exceed 2 metres.
EASYFIT
'X' plus 47mm (RH)
(must include 50mm min.
side clearance)
'X' plus 183mm (LH) = flue length
*STD/EXTD flue only
TOP STD/
EASYFIT
REAR
SIDE R.H.
SIDE L.H.
TOP EXTD.
REAR
SIDE R.H.
SIDE L.H.
REAR STD.
REAR 75 142 510 443 -
MINIMUM
WALL
THICKNESS
MINIMUM
FLUE
LENGTH
MAXIMUM
FLUE
LENGTH
"Y"
BOILER MOUNTING FACE
TO EXTERNALWALL FACE
"X"
BOILER CASINGTO
EXTERNALWALL FACE
MAXIMUM DISTANCE FROM
97
96
232
547
-
-
-
551
415
75
75
75
75
75
75
97
96
232
840
840
840
817
-
-
-
821
685
570
570
570
FLUE
PACKS
NOTE :
IF IT IS NECESSARY TO CUT THE DUCTS
TO ACHIEVETHE "FLUE LENGTH" MAKE SURE
THAT THE OVERLAPS ARE AS FOLLOWS :-
THE OVERLAP FOR AIR DUCT = 25mm
THE OVERLAP FOR FLUE DUCT = 50mm
9354

10
221899A
SIDE FLUE
115mm
TOP FLUE OUTLETS
115mm
MINIMUM
HOLES
BOILER
CENTRE LINE
FLUE
CENTRE LINE
BOILER
FIXING POINT
BOILER
FIXING POINT
REAR FLUE
OUTLET
115mm
MINIMUM
HOLE
EASYFIT TOP
FLUE OUTLET
115mm MINIMUM
HOLE
EASYFIT TOP
FLUE OUTLET
115mm MINIMUM
HOLE
4 Flue and Appliance Preparation
NOTE:Makesurethattheductingsdonotslopedowntowards
the boiler.
4.1 Flue Position and Length
Determineflue application,lengthand terminal positionbefore
starting.
Refer to diagram 4.1.
IfyouareusingaFlueBendoraVerticalFlueKit,pleasefollow
the instructions supplied with the kit.
To make a neat finish to the flue outlet a flue collar kit, part No.
900850, with instructions, is available, see diagram 4.2.
Note: If required an optional wall liner kit, part no. 900862, is
available complete with instructions.
4.2 Flue Preparation
All flue assemblies are designed for internal installation, given
that there is sufficient clearances opposite to the flue for the
installation of the flue.
If there is insufficient clearance the flue can be installed from
outside.
For a wall thickness up to 300mm, provided that there is
sufficient space and the optional wall liner kit is used, the flue
can be installed from the inside.
For a wall thickness of over 300mm the external flue hole will
needto bemade good fromthe outside,thisalso appliesif you
use the flue kit without the optional wall liner kit, irrespective of
wall thicness.
4.3 Rear, Top and Side Flue Application
Select the boiler location and flue application, with due regard
to the terminal position, see diagram 2.1.
Takethetemplatefromtheboilerpackandtemporarilyposition
it on the wall, making sure that the minimum clearances are
maintained, see diagram 4.3.
Mark the centre line position of the flue, "Top" or "Rear" as
diagram 4.3.
Forasideflue,extendcentrelineof"Top"toL.H.orR.H.corner.
Mark the position of the centre of the flue and boiler, as
diagram 4.3.
4.4 Flue Hole Cutting
Having marked out the flue centre cut a hole for the flue using,
preferably, a 115mm minimum core drill.
4.5 Wall Mounting Bracket
Repositionthetemplate,makingsureofdimensionalalignment
with the flue hole.
Mark the boiler fixing points and mounting bracket positions,
see diagram 4.4, drill and insert plugs.
Note: The lower mounting bracket is fixed to the boiler.
Drill the holes and insert wall plugs.
SecurethetopmountingbrackettothewallwithtwoNo.12x2in
woodscrewsoneoneachsideofthebracket,seediagram4.4.
Alternative fixing positions are provided in the bracket, if
required.
4.6 Flue Duct
Extend the telescopic flue to the required length, making sure
that the minimum overlap is no less than 25mm, and that the
flue terminal projects 15mm minmum beyond wall face, see
diagram 4.1.
Carefully drill though air duct pilot hole and secure with self
tapping screw provided in fittings pack, see diagram 4.1.
Diagram 4.3
9351
Diagram 4.4
7317
MOUNTING
BRACKET
SECURING
SCREW
WALL
PLUG
MOUNTING
BRACKET
FIXED TO BOILER
WALL
PLUG
Diagram 4.2
7148
OPTIONAL
FLUE
COLLAR

11 221899A
Seal the joint with the tape provided.
If the flue system requires the addition of flue extension kits,
drill,sealandsecure themwiththeselftappingscrew andtape
provided. Thecompletedfluesystemmustnotexceed3metres,
see relevant part of diagram 4.1.
Note: Should any one of the flue sections require cutting to
obtain desired flue system length, cut the 1metre extension kit
at the end opposite the expanded end.
Iftheboileris nottobefittedforsome timecovertheholeinthe
wall.
Note: If a horizontal flue extension is required it must be used
in conjunction with the standard flue, see diagram 4.1.
IMPORTANT: When using the standard flue kit (either rear
outlet or top outlet fixing), the terminal restrictor must be
fitted.Thisisnotfittedforanyotherfluetype/arrangement.
Note:Therearetworestrictorsinthelooseitemspack,use
the one stamped “A” for the Micron 40FF.
Take the terminal restrictor and position the clamping bracket
makingsuretheclampingbracketnibprotrudesintheslotofthe
terminal restrictor and secure with locking screw, but do not
tighten, see diagram 4.6.
Engage the terminal restrictor on the flue terminal by hooking
it over the terminal end and engaging the clamping bracket
behindtheinnerringoftheterminalsecuringitbytighteningthe
locking screw, see diagram 4.6
4.7 Internal Access Flue
Ifaccesstotheoutsidewallisnotpractical,thefluesystemcan
be installed from inside. Use of the optional wall liner kit is
required.
4.8 Rear Flue Fixing
Fittheselfadhesivefoamsealprovidedinthefluepackaround
the air duct at the position shown in diagram 4.1.
Make sure that the ductings do not slope down towards the
boiler.
Make good around the flue outside after installation of the
boiler.
Important:Ifthewalllinerkitisused,theselfadhesivefoamseal
included in the wall liner kit must be used in place of the one
supplied with the flue pack, see diagram 4.5 for position of self
adhesive seal.
4.9 Top, Side Flue Fixing
Make sure that the ductings do not slope down towards the
boiler.
Make good the area around the flue inside and outside after
installation of the boiler.
Important:Ifthewalllinerkitisused,theselfadhesivefoamseal
included in the wall liner kit must be used in place of the one
supplied with the flue pack, see diagram 4.5 for position of self
adhesive seal.
4.10 Flue Positioning
Pushthe flueassembly into andthrough thehole such thatit is
withinthewall,anddoesnotstickoutintotheroom. Donotpush
theflueassemblytoofarintotheholeasithastobepulledback
into the boiler and secured.
4 Flue and Appliance Preparation
Diagram 4.5
FOAM SEAL
FOAM SEAL
WALL THICKNESS-
OVER 300mm
15mm
WALL THICKNESS-
UP TO 300mm
Q-35mm
Q
Q
7102
Diagram 4.6
7323
RESTRICTOR
CLAMPING
BRACKET
CLAMPING
BRACKET NIB
FLUE
TERMINAL
LOCKING
SCREW
TERMINAL RESTRICTOR
SHOWN FITTED
WITH WALL LINER KIT ONLY
STANDARD 510mm REAR AND
STANDARD 570mm TOP FLUE ONLY
7332

12
221899A
Diagram 5.3
7199
TAIL PIPE
TUBING
NUT RUBBER
WASHER
AIR VENT
FLOW
RETURN
5 Boiler Installation
Diagram 5.1
CONTROLS COVER
6769
CASE
SECURING
SCREWS
VIEW ON
COVER TOP
5.1 Unpacking
Open the carton, check the items supplied against the boiler
pack contents list on the carton flap.
5.2 Boiler Preparation
With the boiler still in the bottom tray, remove the casing front
cover. To do this open the controls cover first, then by undoing
thetwoscrews at thebottomandtheone atthetop,liftthe front
cover off, see diagram 5.1.
Place front cover in a safe place on one side until required.
Remove boiler from carton.
From the fittings pack, slide a tubing nut and washer on to the
returnand flowtailpipeswhicharesuppliedwiththeboiler,see
diagram 5.2.
Connectthereturnandflowtailpipestotheboiler,seediagram
5.2.
Fit suitable compression fittings to the tail pipes.
For pipework entering the boiler from below, an optional flow
pipe incorporating an air vent is available, kit No. 458130. The
return tail pipe supplied with the boiler will need to be cut, see
diagram 5.3.
Note: If the installer wishes to adapt the standard pipework he
maydoso,but must incorporateanair-ventatthehighest point
on the flow pipe, see diagram 5.11.
5.3 Mounting the Boiler
Ensuretofittheblankingplate andgasketontheboilerflue
outlet not being utilised, see diagram 5.6.
Iftherearflueoutletistobeutilisedfortheinstallationoftheflue,
it will be necessary to connect the flue spigot and gasket to the
outlet, using self tapping screws provided, see diagram 5.6.
Note:Thespigotwouldonlybefittedtothetopflueoutletwhere
averticalfluekitorincertainfluebendorientationsisincorporated.
Instructions are supplied with these kits.
Lift the boiler into position, hooking over the top mounting
bracket.
Note: Anti-theft screw kits are are available, part no’s: 458113,
458114.
Important:Securelowerbrackettowallwithscrewintowall
plug already prepared.
Note:It willbe necessary tomove thecontrolbox toaccess the
bracketby slackeningitsretaining screw andswingingit outon
its hinge, see diagram 5.10.
Where the boiler is located in a restricted place, see diagram
1.3, it may be necessary to remove the control knob to enable
the control box to be fully swung out.
If the top flue outlet is to be utilised, secure the top turret and
gasket or flue spigot and gasket depending on desired flue
orientation in position with the 2 taptite and 2 self tapping
screws provided, see diagram 5.9.
Note:Ensurethatthetaptiteandself-tapscrewsarepositioned
as shown in diagram 5.8 to enable the air deflector to be fitted
correctly.
Iffixingtothebackoftheboiler,i.e.spigot,slidetheflueinto the
spigotuntil itengages inthebayonet connectionand thentwist
anticlockwise to lock, see diagram 4.1.
Make sure the fitting of the flue to the boiler is correct.
The fan assembly may also be removed or slid forward about
halfway out of the boiler, to ease access, by removing the
securing screw at the front, see diagram 5.5.
The fan assembly may also be removed or slid forward about
halfway out of the boiler, to ease access.
Disconnectthethe blueandpurpleelectricalconnectionstothe
fan,and the airpressureswitch tube connections,seediagram
5.5.
Diagram 5.2
7200
TAIL PIPE
TUBING
NUT
RUBBER
WASHER
FLOW
RETURN

13 221899A
5 Boiler Installation
Diagram 5.4
MOUNTING
BRACKET
NOTE:
PIPES REMOVED FOR CLARITY
SECURING
SCREW
Note: Remove the electrical connections by pulling insulation
boots only.
Remove the securing screw at the front, see diagram 5.5.
The fan assembly may now be slid forward.
Rear Flue fixing
Fitthefanelbowandsecurewithjubileecliptothefanoutlet,do
not tighten yet, see diagram 5.7.
Fit the retaining clamp of the fan elbow, bending the straps
aroundthefanelbowraisedclampingsurfacesbutdonotfasten
the clasp, see diagram 5.7.
It is important that the retaining clamp is fitted the correct way
round, so that the straps locate on to the fan elbow raised
clamping surfaces.
Reconnecttheblueandpurpleelectricalconnectionstothefan,
the polarity of the connections is not important.
Pull the flue duct into the fan elbow to engage.
Important: It is essential to make certain that the flue duct
is fully located into the fan elbow until it can go no further.
Fastenthefanelbowretainingclampclaspthussecuringit,see
diagram 5.7.
Secure the fan elbow to the fan outlet with the Jubilee clip.
Reposition fan assembly.
Top Flue fixing
Fitthetwo“O”ringsfromthelooseitemspackontotheflueduct
extension, there are recesses on the flue duct extension for
locating them, see diagram 5.7.
Fit the air deflector in position using the rear left hand taptite
screw and the one diametrically opposite which hold the top
turret and secure with the wing nuts provided but do not fully
tighten, see diagram 5.8.
Swing the air deflector out from right hand side (the slot in air
deflectorallowsyoutodothis)toalloweasyaccesstofittingfan
assembly.
Note: Apply soap to seals on flue duct extension piece to help
it slide in, be careful not to damage ‘O’ ring.
Insertflueductextensionpieceintotop turret, seediagram5.7.
Note:Makesurethattheflueductextensionpieceispositioned
so that the nibs are upper most, see diagram 5.7.
Locate the fan elbow with jubilee clip on the fan outlet, do not
tighten yet, see diagram 5.7.
Reconnecttheblueandpurpleelectricalconnectionstothefan,
the polarity of the connections is not important.
Reposition the fan assembly and draw down the flue duct
extension piece onto the fan elbow, see diagram 5.7.
Fit the retaining clamp on the fan elbow raised clamping
surfaces,bendingthestrapsaroundthefanelbow andfastening
theclaspthussecuringittotheflueductextension,seediagram
5.7.
It is important that the retaining clamp is fitted the correct way
round, so that the straps locate on to the fan elbow raised
clamping surfaces.
Secure the fan elbow to the fan outlet with the Jubilee clip.
Swingtheair deflector inpositionandsecure, see diagram8.7.
Continued.
Secure the fan assembly by replacing securing screw, see
diagram 5.5.
Reconnect the air pressure switch tube, see diagram 5.5.
5.4 Water Circulation System
Complete the water connections to the boiler.
Fill, vent and flush the system.
Check for any water leaks and put right.
7107
MOUNTING
BRACKET
Diagram 5.5
ELECTRICAL
CONNECTIONS
7131
SECURING
SCREW
CLEAR AIR
PRESSURE TUBE
IMPORTANT:
REMOVE ELECTRICAL CONNECTIONS
BY GRIPPING THE BOOT ONLY

14
221899A
FLUE
DUCT
EXTENSION
JUBILEE
CLIP
TOP
TURRET
9355
RETAINING
CLAMP
" O " RINGS
NIBS
Diagram 5.7
5 Boiler Installation
JUBILEE
CLIP
REAR
CONNECTION
(within casing)
Diagram 5.6
BLANKING
PLATE
7150
TOP
CONNECTION
RETAINING
CLAMP
5.5 Gas Connection
Make the gas connection to the Rc1/2in gas service cock, see
diagram 6.2.
Thewholeofthegasinstallation,includingthemeter,shouldbe
inspected,testedforsoundnessandpurgedinaccordancewith
the current issue of BS6891.
5.6 Control Box Access
Slacken the control box securing screw, see diagram 5.10.
Swing the box out on its hinge.
5.7 Electrical Connection
WARNING. This boiler must be earthed.
Note: If an optional programmer is to be installed, it should be
fittedatthisstage,seeseparateinstallationinstructionssupplied
with programmer
Take care not to damage any internal wiring.
Using heat resistant (85oC) cable of at least 0.75mm2 (24/
0.2mm)andofasuitablelength,threadthroughthegrommetat
therearofthecontrolbox,throughthecableclampandconnect
to appropriate terminals. Tighten cable clamp screws, see
diagram 5.10.
Standard colours are, brown - live (L), blue - neutral (N) and
green/yellow - earth ( )
The mains cable outer insulation must not be cut back external
to the cable clamp.
Make sure the cable is suitably secured.
Whenmakingconnections, makesurethatthe earth conductor
ismadeofagreaterlengththanthecurrentcarryingconductors,
so that if the cable is strained the earth conductor would be the
last to become disconnected.
FAN ELBOW
GASKET
6791
SCREWS
(4)
SPIGOT
REAR FLUE FIXING
TOP FLUE FIXING
FLUE DUCT
EXTENSION
PRESS PRESS
RETAINING
CLAMP
FAN
ELBOW
PRESS
CLASP
SCREWS
(4)
FAN ELBOW
CLAMPING
SURFACE

15 221899A
MAINS
SUPPLY
230V~50Hz
BLOCK
CONNECTOR
bl
LSN
g/yg/y
g/y
br
b
b
Diagram 5.10
5 Boiler Installation
SECURING
SCREW
6767
CONTROL
BOX
5.8 Pump Connection
The pump must be connected to the external controls.
5.9 Testing
Checks to ensure electrical safety must be carried out by a
competent person.
After installation of the system, preliminary electrical system
checks as below should be carried out:
Diagram 5.9
TOP
TURRET
6793
GASKET
SCREWS
(4)
TOP TURRET
FLUE OUTLET
FLUE
DUCT
EXTENSION
HINGE PIN
7665
Diagram 5.8
CABLE
CLAMP
GROMMET
1. Test insulation resistance to earth.
2. Test earth continuity and short circuit of all cables.
3. Test the polarity of the mains.
The installer is requested to advise and give guidance to the
user of the controls scheme used with the boiler.
Fit the casing.
Diagram 5.11
7333
TAIL PIPE
TUBING
NUT
AIR VENT
RETURN
FLOW
RUBBER
WASHER
AIR
DEFLECTOR
WING NUT
TAPTITE
SCREWS (2)
SELF-TAP
SCREWS (2)

16
221899A
6 Commissioning
Diagram 6.2
BURNER
PRESSURE
TEST POINT
NOTE: Do not adjust any
other setting screws
6792
GAS PRESSURE
ADJUSTMENT
SCREW
(CUP REMOVED)
MULTIFUNCTIONAL
CONTROL
Important Note : The warning notice attached to the
front of the boiler casing must only be removed by
the user.
Please ensure the “Benchmark” logbook is completed and left
with the user.
6.1 All Systems
Commissioningshouldbecarriedoutbyacompetentpersonin
accordance with the current issue of BS6798.
UNDER ALL CIRCUMSTANCES the case must be correctly
fitted and sealed, unless fault finding.
Makesurethatthesystemhasbeenthoroughlyflushedoutwith
cold water without the pump in place.
Refit the pump, fill the system with water, ensuring that all the
air is properly vented from the system and pump.
6.2 Sealed Water Systems Only
Fill until the pressure gauge registers 2.7bar (40lbf/in2). Clear
any air locks and check for water soundness.
Check the operation of the safety valve, by allowing the water
pressure to rise until the valve opens. The valve should open
within +/- 0.3bar (+/- 4.3lbf/in2) of the pre-set pressure. Where
this is not possible conduct a manual check and test.
Note:Fita suitabledischargepipeto thesafetyvalveand route
it to outside the building so that any discharge can be seen but
will not cause injury to persons, damage to property or any
electrical installation.
Release cold water to initial system design pressure.
Thesetpointeronthepressuregaugeshouldbesettocoincide
with the indicating pointer.
6.3 Initial Lighting and Testing
CAUTION. This work must be carried out by a competent
person, in accordance with the current issue of BS6798.
Make sure that boiler case is fitted securely
Make sure that all naked lights and cigarettes are out.
Open the control cover, refer to 'Instructions for Use' and
identify the controls, see diagram 9.1.
Remove fascia, see diagram 6.1.
Check that the boiler is isolated from the electrical supply.
Makesure thatthetemperature controlisturned tothe “0” “Off”
position, see diagram 9.1.
Undo the screw which holds control box , see diagram 5.10.
Swing open control box.
Turn the gas service cock “On”, see diagram 6.2. A 14mm
spanner may be required for this.
Purge in accordance with the current issue of BS6891.
Replace control box.
Turn on the electrical supply.
WARNING. The multifunctional control and fan operate on
mains voltage, terminals will become live.
If programmer control fitted, make sure it is in the ON mode.
Make sure that any remote controls are calling for heat.
Turn the temperature control clockwise to “Max”.
The ignition system will operate to light the boiler. After a pre-
set time if ignition has not taken place the boiler will shutdown.
To re-start the lighting sequence, turn the temperature control
to “0”, then fully clockwise to “Max”.
Aftertheburnerhaslit,the“Burneron”neononthecontrolpanel
will come on.
GAS COCK
(ON)
Diagram 6.1
CONTROLS COVER
7318
FASCIA
SECURING
SCREWS
FASCIA
GAS COCK
(OFF)
Isolate the boiler from the electrical supply.
Loosen the burner pressure test point screw and connect a
suitable pressure gauge, see diagram 6.2.
Replace control box.
Switch on the electrical supply to the boiler.
40FF MIN. MED. MAX.
APPROX. m3/h 1.07 1.23 1.40
GAS RATE ft3/h 37.69 43.53 49.4
Table 2

17 221899A
6 Commissioning
6.4 Testing - Electrical
Turn the boiler temperature control knob fully clockwise to the
maximum setting, which is about 82oC (180oF).
The lighting sequence is automatic as follows:
The fan operates and after a short period of time, the spark
ignition operates, the solenoid opens, then the burner will light
shownbythe"BurnerOn"neononthecontrolpanellightingup.
The burner will stay alight until switched off, either by the
temperature control or a remote system control.
To make sure that the flame supervision device is working
correctly the following should be done.
With the burner alight, turn the gas service cock “Off”, see
diagram 6.2.
After a short period the burner will go out.
Thecorrectworkingoftheflamesupervisiondeviceisshownby
the “Burner On” neon going out and the ignition sequence
starting up.
After a short period the boiler will shut down.
If the above does not happen, refer to fault finding Section 9.
To carry on turn the gas service cock “On”, see diagram 6.2.
To re-start the lighting sequence, turn the temperature control
knob to “0” then fully clockwise to Max.
During normal operation when the boiler switches “Off”, the
burner will go out. The automatic lighting sequence will work
again when heat is required.
6.5 Testing - Gas
With the boiler on proceed as follows:
Undo the screw which secures control box, see diagram 5.10,
Open control box, see diagram 5.10.
WARNING. The multifunctional control and fan operate on
mains voltage, terminals will be live.
Test for gas soundness around the boiler gas components
using a suitable leak detection fluid, in accordance with the
current issue of BS6891.
Check the burner gas pressure at least 10 minutes after the
boiler has lit, refer to Data Label.
If necessary remove cap and adjust the gas pressure to obtain
the required setting turning screw clockwise, to decrease
pressure, see diagram 6.2.
Replace cap.
Shouldanydoubtexistaboutthegasrate,checkitusingthegas
meter test dial and stop watch, at least 10 minutes after the
burnerhaslit,makingsurethatallothergasburningappliances
and pilot lights are off.
ThegasratesshowninTable2areforguidanceonly,dependent
on the heat setting.
Turn the temperature control knob fully anticlockwise to “0”.
Isolate from the electrical supply.
Removethe pressuregauge from thetest pointand refit screw,
making sure a gas tight seal is made.
Refit control box and fascia.
Note: The fixing holes of the fascia are slotted to allow fine
adjustment to align control cover with casing.
When the temperature control is turned to the “0” position, by
hand, wait at least 30 seconds before turning On again.
Theremaybeaninitialsmellgivenofffromtheboilerwhennew,
this is quite normal and it will disappear after a short period of
time.
6.6 Testing - All Water Systems
Allow the system to reach maximum working temperature and
examine for water leaks.
There should be no undue noise in the system.
The boiler should then be turned off and the system drained off
as rapidly as possible, whilst still hot.
Refill system.
6.7 Open Vented System
Ensure there is no pumping over of water or entry of air at the
open vent above the feed and expansion cistern.
6.8 Adjustment - Fully Pumped Open Vented
and Sealed Water Systems
When commissioning the system the boiler should first be fired
on full service, that is, central heating and domestic hot water.
Adjust the pump to the system design setting then balance the
system, making adjustments as necessary. .
6.9 Thermostatic Radiator Valves
If thermostatic radiator valves are fitted care must be taken to
ensure that there is an adequate flow rate through the boiler
when they close, refer to the current issue of BS7478 for
guidance. If fitted to all radiators ensure a bypass is fitted and
adjusttoachieveatemperaturedifferencenogreaterthan20oC
between flow and return with the thermostatic valves closed.
6.10 Completion
Adjusttheboilertemperaturecontrolandanysystemcontrolsto
their required settings.
Instruct and demonstrate the safe and efficient operation of the boiler, heating system and domestic hot water system.
Advisetheuser,thattoensurethecontinuedefficientandsafeoperationoftheboileritisrecommendedthatitischeckedandserviced
at regular intervals. The frequency of servicing will depend upon the particular installation and usage, but in general once a year
should be enough.
Draw attention, if applicable, to the current issue of the Gas Safety (Installation and Use) Regulations, Section 35, which imposes
a duty of care on all persons who let out any property containing a gas appliance.
It is the Law that servicing is carried out by a competent person.
Advisethe user oftheprecautions necessary topreventdamage tothesystemand buildingintheevent oftheheatingsystem being
out of use during frost and freezing conditions.
Reminder - Leave these instructions and the “Benchmark” logbook with the user.
7 Instructions to the User

18
221899A
Diagram 8.4
COMBUSTION
CHAMBER
COVER
7226
SCREW
BURNER
RETAINING
SCREW
BURNER
SCREW
Diagram 8.3
6778
8 Servicing
Diagram 8.2
BAFFLE
(6 off)
6779
REMEMBER,Whenreplacingapartonthisappliance,useonly
spare parts that you can be assured conform to the safety and
performance specification that we require. Do not use
reconditionedorcopypartsthathavenotbeenclearlyauthorised
by Hepworth Heating Ltd.
Products of Combustion Check
Note: To obtain a products of combustion reading, remove the
capfromthesampling point,locatedontopofthe inner casing,
see diagram 8.1.
Connect the analyser tube onto the nipple.
Switchontheelectricalsupplyandgassupplythenoperatethe
boiler.
Oncompletionofthetestswitchofftheelectricalsupplyandthe
gas supply, remove analyser tube and replace sampling point
cap.
Servicing
Beforeservicingturnoffthegasandisolatetheelectricalsupply
to the boiler.
Aftercompletingaservicealwaystestforgassoundness,make
electrical checks and carry out functional check on controls.
Unless stated otherwise all parts are replaced in the reverse
order to removal.
8.1 Access
Remove the boiler case, see diagram 5.1 and Section 5.2.
8.2 Burner
Remove front combustion chamber cover which is secured by
two screws, see diagram 8.3.
Pullbackelectrodeprotectionsleeveanddisconnectelectrode
connection along with earth connection, see diagram 8.6.
Remove the burner retaining screw located at the right hand
side of the burner, see diagram 8.4.
When completed, take hold of burner and slide it to the left
clearingtheinjectorand remove. Takecarenottodamagethe
combustion chamber insulation
Usea vacuumcleaner orsuitable stiffbrush (notwire) toclean
theburnerthoroughly,makingsure that alltheburnerportsare
clear and unobstructed.
On refitting and after cleaning the heat exchanger make sure
the burnerisfittedcorrectly,thatis,locatedonthe injectorand
horizontal.
Note: It is advisable while servicing the burner to check the
combustion chamber insulation and replace if damaged, see
Section 10.10.
8.3 Cleaning Heat Exchanger Flueways
Disconnectthe airpressureswitch tubeconnection, bothclear
tubes from test nipple, see diagram 8.1.
Removetheblueandpurpleelectricalconnectionsfromthefan
see diagram 5.5.
If top outlet installation: Remove air deflector, or it may just be
swungbackbylooseningthewing-nuts,toenablefanassembly
to be removed, see diagram 8.7 and Section 5.3.
Remove the fan assembly complete with the flue elbow, see
diagram 5.5 and Section 5.3
Place a sheet of paper in the base of the combustion chamber
and over the injector to prevent particles entering.
Remove the baffles, see diagram 8.2.
Diagram 8.1
CLEAR AIR
PRESSURE
TUBES
SAMPLING
POINT
7231

19 221899A
8 Servicing
Diagram 8.5
BURNER
INJECTOR
6801
Clean the heat exchanger flueways with a suitable stiff brush.
Remove the paper together with any debris.
8.4 Injector
With the burner removed the injector can be inspected and
cleaned as necessary, see diagram 8.5.
Forcleaning donot use awire orsharpinstrument onthe hole.
If removed, use a little suitable sealant on the external thread
when refitting to make sure a gas tight seal is made.
8.5 Operational Checks
After completing a service and before fitting the case, check
condition of the case seal and renew if necessary.
Examine flue hood and terminal to make sure they are clean
and clear of obstructions.
Refit all parts.
Lighttheboilerandcarryoutthefunctionalchecksasdescribed
in Section 6.
9.1 Electrical
Important. On completion of the Service/Fault Finding task
which has required the breaking and remaking of the electrical
connections the earth continuity, polarity, short circuit and
resistance to earth checks must be repeated using a suitable
multimeter.
Refer to: Boiler Fault Finding, see diagram 9.2, Fault Finding
WiringDiagram,seediagram9.3,PictorialWiringDiagram,see
diagram 9.4.
9.2 Electrical Supply Failure
Failure of the electrical supply will cause the burner to go out.
Operationwillnormallyresumeontherestorationoftheelectrical
supply.
If the burner does not relight after an electrical supply failure
openthe control cover,seediagram 9.1andif the resetneonis
lit, see diagram 9.1, turn control knob on the front of the control
box to “0”, and then back again, see diagram 9.1.
If the safety temperature limiter operates at any other time, do
as above, the burner should relight. If the fault persists refer to
fault finding chart.
9 Fault Finding
CONTROLS COVER
7166
Diagram 9.1
CONTROL
KNOB
6771
Diagram 8.7
7229
AIR
DEFLECTOR
WING NUT
(2)
Diagram 8.6
ELECTRODE
7389
SCREW
PROTECTION
SLEEVE
EARTH
3.6 +1.1

20
221899A
9 Fault Finding
Diagram 9.3
7424
Diagram 9.2
7315
FUSE
TYPE F4A
AIR PRESSURE SWITCH CONNECTIONS
FAN
EV1
EV2
SPARK
ELECTRODE
AIR
PRESSURE
SWITCH
SL
(N/O)
(C)
(N/C)
br
br
bk prgy y br bk
KEY
bk BLACK
br BROWN
b BLUE
p PURLPLE
r RED
y YELLOW
gy GREY
MAIN TERMINAL STRIP CONNECTIONS
PRINTED CIRCUIT BOARD CONNECTIONS
O/H
CUTOFF
b
b
b
N
b
Check for 230V ac
between N and common
contact on air
pressure switch.
Check for 230V ac
between N and normally
closed contact of air
pressure switch.
Is there 230V ac between
Ls and N
Ensure that any external controls are calling for heat and circuit water is cold. If overheat neon
lit - check water system for overheating, reset by turning temperature control knob off and on.
If neon 6 is lit flame failure has occured. Reset boiler by turning temperature control to off and then on.
Do not operate the boiler without combustion chamber front fitted.
Before carrying out fault finding, ensure that gas, electricity and water are available at the boiler.
Is neon 1 lit? NO Check power supply
Is neon 2 lit? NO
YES YES
Faulty thermistor.
Replace.
Disconnect the 2 way
thermistor plug from the PCB.
Check that there is a resistance
between 14k - 2.5kOhms.
Faulty PCB.
Replace.
Is neon 3 lit? Faulty PCB.
Replace.
YES
NO
NO
YES
YES
Faulty air pressure
switch. Replace.
Does sparking take place
(Listen for spark discharge.)
?Faulty PCB.
Replace. Check for 230V ac
between N and brown
and between N and black,
3 way connector on PCB.
Faulty PCB.
Replace.
NO
NO
Check continuity of
gas valve harness.
Faulty gas valve.
Replace.
Faulty harness.
Replace.
NO
YES
NO
Is the fan turning?
YES NO Is there 230Vac
on fan?
Faulty
PCB. Faulty
fan.
Does burner light?
YES
YES
YES
YES
NO
NO
Is neon 4 lit? NO
YES
Appliance working
satisfactorily.
Is integrity of
electrode and
HT lead good?
Replace as
necessary Faulty
PCB.
YES
NO
YES
NO
NO