7
221763A
FRONT CLEARANCE
Diagram 1.5
0906
700 (27
1/
2
in.)
BOILER
WALL OR
FIXTURE
1 General Data
2 Water Systems
Diagram 2.1
0869
27metre
Max.
PUMP
To Heating
Circuit
INDIRECT
CYLINDER
22mm VENT
15mm COLD FEED
REFER TO BS 5546
28mm
Distributor tube in
pumped return
connection
BOILER
CL
DRAIN OFF
COCK
To facilitate minimum clearances it may be necessary to modify
the kitchen units or fixtures, depending upon which type of
connections are used.
A front access clearance should be provided as shown in
diagram 1.5.
The minimum gap behind the top casing is as shown in diagram
1.1. The boiler can be sited further away from the wall if required
to align with kitchen units etc. Refer to Section 3.5.
Combustible wall material must be 25mm (1in) away from flue
components. Refer to Section 3.5.
A special top casing, part No. 425524, can be purchased to
enable the boiler casings to be arranged flush with 600mm (23
5
/
8
in) deep work tops and kitchen units.
Where the installation of the boiler will be in an unusual location,
special procedures are necessary, the current issue of BS6798
gives guidance on this.
A compartment used to enclose the boiler must be designed
and constructed specifically for this purpose. An existing
cupboard or compartment modified for the purpose may be
used. Details of essential features of cupboard design are
given in the current issue of BS6798.
If the boiler is to be installed in a compartment, make sure that
nothing will obstruct the openings/vents in the compartment.
2.1 Water Pressure Head
This boiler shall only be connected to a cistern supply, with a
minimum head of 1 metre (3ft) and a maximum of 27 metres
(90ft) and having an open vent in the system.
The boiler must not be connected to a sealed water system.
2.2 Inhibitor
Attention is drawn to the current issue of BS5449 and BS7593
on the use of inhibitors in central heating systems.
When an inhibitor is to be used in the system, contact should be
made with an inhibitor manufacturer so they can recommended
their most suitable product.
When using in an existing system take special care to drain the
entire system, including the radiators, then thoroughly cleaning
out before fitting the boiler whether or not adding an inhibitor.
2.3 Gravity Domestic and Pumped Heating
It is recommended that a cylinder thermostat is used to prevent
the stored water temperature becoming unnecessarily high.
The primary flow and return must be 28mm. The installation
must comply with the current issue of BS5546 and BS6700, see
diagram 2.1.
If the above conditions cannot be met, it is suggested that a fully
pumped system be used.
2.4 Fully Pumped System
Where a single pumped, flow and return is taken from the boiler,
refer to diagram 2.2.
2.5 Circulation Pump
The pump should be set to give a temperature difference of
11
o
C (20
o
F) across the system. At the appropriate flow rate the
resistance through the boiler can be found from the pressure
loss graph, diagram 2.3.
If possible use a pump with integral valves, if not fit valves as
close as possible each side of the pump.
Note: If the pump is to be fitted inside the boiler casing a heat
shield kit is required. Kit No. 425838.
1.8 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 of fuel and power, 1995 edition - Appendix
G, table 4b.
