15
British Gas 4100 & 4125 RD2 -
Installation & Servicing
INSTALLATION
FLUE OUTLET
12 PREPARING THE BOILER
Notes
.
z
Before placing the boiler in the selected position any gas
and water connections at the rear of the boiler should be
prepared, due to the possible lack of access.
z
The pump may be fitted to the FLOW or the RETURN.
13 REAR FLUE ASSEMBLY - Exploded view
5 6
7
8
1
2
3 4
Mex
1842
LEGEND
1.
Terminal.
2.
Weather seal.
3.
Flue assembly.
4.
Boiler sealing ring.
5.
Flue extension tube.
6.
Sealing plate.
7.
Flue connector.
8.
Turret access cover.
1.
The boiler turret assembly is factory built for rear flue installation.
2.
Remove the turret access cover.
3.
Fit the flue extension tube (supplied with the boiler) to the flue connector,
rotate in the bayonet slot and secure with the M4 screws.
For wall thickness 114mm to 600mm
Connections
Sensor Position
(as viewed at front)
Back Section
Front Section
CH
DHW
Flow
Return O/heat
Flow Return Flow
Return Top
Bottom Bottom
LH
LH
RH
RH
LH
LH
RH
LH
RH
RH
LH
LH
RH
LH
RH
RH
LH
LH
RH
RH
LH
RH
LH
LH
RH
RH
LH
RH
Table 8 - Gravity Dom. Hot Water & Pumped Central Heating
Table 7 - Fully Pumped Systems
Connections
Sensor Position
(as viewed at front)
Back Section
Front Section
Flow
Return
Flow
Return
O/heat
Top
Bottom
Top
Bottom
Bottom
LH
LH
LH
LH
RH
LH
RH
LH
RH
LH
RH
RH
RH
RH
LH
RH
LH
RH
LH
RH
1.
Screw the distributor tube (supplied with a 1" BSP x 28mm
copper adaptor) into the selected heating return tapping,
using an appropriate jointing material.
IMPORTANT.
It is
IMPERATIVE
that the index mark on the distributor tube
bush is in alignment with the mark on the section boss, as
shown in Frame 3.
DO NOT disturb it when connecting subsequent pipework.
Fully pumped systems using more than 1 pump, serving
separate zones, must have a common return connection to the
distributor tube.
2.
Select the desired pumped flow tapping and fit a 28mm x
1"BSP adapter.
3.
Fit the boiler return sensor pocket into the appropriate front
section tapping as follows:
a.
Screws the hexagon bush into the tapping using
approved jointing material. Refer to Tables 7 and 8.
b.
Fit the 'O' ring into the bush.
c.
Insert the sensor pocket, ensuring that it enters the hole
in the end of the distributor tube.
d.
Secure the pocket with the 3 screws and washers
provided.
4.
Screw the supplied overheat thermostat sensor pocket into
the appropriate front section tapping using approved
jointing material. Refer to Tables 7 and 8.
5.
Screw the supplied boiler flow sensor pocket into the
appropriate front section tapping, using an approved
jointing material. Refer to Tables 7 and 8.
6.
Fit 28mm x 1"BSP adapter pipe fittings to the appropriate
rear tappings for DHW if required and plug any unused
tappings.
