19
4.
Tighten union nuts so that they form a tight seal.
Tighten the union nuts as tightly as necessary and
ensure that the components are undamaged and
are functioning correctly throughout service life.
Observe torque settings if a torque wrench is avail-
able.
Check for gas tightness to BSI 6891.
Torque settings:
■
Union nuts G
¾
: 30 Nm
■
Union nuts G
½
: 24 Nm
When carrying out any work on gas connection fit-
tings, hold with a suitable tool. Never transfer any
forces to the internal components.
Connections on the heating water and DHW sides
If the connections have not been fitted previously,
make the connections on the heating water and DHW
sides.
Gas condensing system boiler
B
C
D
E
F
A
Fig. 8
Specifications for threads in conjunction with
connection accessories
A
Heating flow R
¾
(male thread)
B
Cylinder flow G
¾
(male thread)
C
Gas connection R
¾
(male thread)
D
Cylinder return G
¾
(male thread)
E
Heating return R
¾
(male thread)
F
Filling/draining
Connection on the heating water side of the DHW
cylinder:
The required intermediate pieces (Rp
¾
, female
thread) on the cylinder flow and return are part of the
connection set for the DHW cylinder.
If no DHW cylinder is being connected, seal off the
connections with caps.
Gas condensing combi boiler
F
A
B
C
D
E
Fig. 9
Specifications for threads in conjunction with
connection accessories
A
Heating flow R
¾
(male thread)
B
DHW R
½
(male thread)
C
Gas connection R
¾
(male thread)
D
Cold water R
½
(male thread)
E
Heating return R
¾
(male thread)
F
Filling/draining
Scald protection
DHW temperatures of over 60 °C can occur with gas
condensing combi boilers. As a result, scald protection
should be installed on site in the DHW pipe.
Installation sequence
Mounting the boiler and making connections
(cont.)
6173886
Installation
