• This boiler is only suitable for installing
internally within a property at a suitable
location onto a fixed rigid surface of the same
size as the boiler and capable of supporting
the boiler weight.
• The boiler must be installed on a flat level
surface to ensure condensate does not enter
the primary heat exchanger.
• The boiler is not suitable for external
installation unless a suitable enclosure is
provided.
• Roof space installations must fully conform to
BS 5410 part 1 section 4.6.9.
Open flue model (CF):
• In order to ensure clean and efficient
combustion an adequate supply of air must
be delivered to the combustion chamber.
• To provide sufficient air a suitable inlet must
be provided into the room or space in which
the boiler is situated.
An air brick or other form of continuous air
supply may have to be built into the installation
in order to ensure an adequate supply of air.
• If the appliance is to be installed in a confined
space or compartment two air vents are
required, one at high level and one at low level.
The minimum free area of each vent is
shown opposite and depends whether the
air is taken from another room or from
outside the building.
• Where the air is taken from another room that
room must contain an air inlet as described
above.
Room sealed balanced flue model (RS):
The appliance does not require a separate vent
for combustion air.
• Installation in cupboards or compartments
require permanent vents for cooling purposes,
one at high level and one at low level, either
direct to outside air or to a room.
• Both vents must pass to the same room or be
on the same wall to the outside air.
The minimum air vent free area is given in the
table opposite.
a: INSTALLATION CLEARANCES:
Diagram ( a ) shows the minimum space
recommended to install the boiler only.
b: SERVICE CLEARANCES:
Diagram ( b ) shows the minimum space
required to carry out an annual service.
c: MAINTENANCE & REPAIR CLEARANCES:
The appliance is suitable for an under worktop
installation providing that the worktop above the
boiler (min 10mm clearance) is removable for
maintenance and repair and the front of the
boiler is not enclosed.
* Remove the flue 'knock-out' panel sections if
this clearance is less than 75mm.
** Due to changes to BS 5410 and modern
building design, these figures no longer
incorporate the adventitious ventilation allowance.
600mm
300mm
100mm
100mm
720mm
1200mm
1
1
55mm
a: RECOMMENDED
INSTALLATION CLEARANCES
b: ANNUAL SERVICE CLEARANCES
600mm
10mm
5mm*
5mm*
530mm
1200mm
865mm
c: MAINTENANCE & REPAIR CLEARANCES
600mm
300mm
5mm*
5mm*
530mm
1200mm
1
1
55mm
MINIMUM AIR VENT AREA (cm
2
) FOR APPLIANCES INSTALLED IN A COMPARTMENT:
1Internal air to and from a space/room inside the building. 2External air to and from directly outside the building.
12/18kW
CF minimum air inlet sizes**
99
138
176
18/25kW
25/32kW
Output
Size cm
2
BOILER LOCATION &
CLEARANCES
Conventional flue
kW
Internal
1
ventilation External
2
ventilation
High
Level
Low
Level
High
Level
Low
Level
12/18
198
279
99
198
18/25
275
413
138
275
25/32
352
528
176
352
Room Sealed flue:
kW
Internal
1
ventilation External
2
ventilation
High
Level
Low
Level
High
Level
Low
Level
12/18
198
198
99
99
18/25
275
275
138
138
25/32
352
352
176
176
BOILER LOCATION &
CLEARANCES
INSTALLATION & SERVICING INSTRUCTIONS FOR WORCESTER GREENSTAR HEATSLAVE 12/18-18/25-25/32
6 720 802 432 issue A 04/2012
17
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