Bosch ZWB28-3A - Connecting Additional Accessories

54 | Making the electrical connections
Copyright (optional information)6 720 643 068 (2011/06)
6.2.4 Connecting additional accessories
B For splash-proof (IP) strain relief, cut the grommet to
match the diameter of the cable.
Fig. 39 Cut off grommets
B Feed cable through strain relief and connect
accordingly.
B Secure the cable on the strain relief.
Bosch room controls
Connect only Bosch room controls to the internal BUS of
this boiler.
For installation and electrical connection of the FB 100
remote control, see installation instructions for the remote
control.
Connecting temperature guard TB 1 (external manual
reset high limit or low water cut off (LWCO))
This connection allows the installation of external safety
switches.
• External manual reset high limit
• Low water cut-off (LWCO)
• Radiant overheat protection
Fig. 40 Electrical wiring TB1
When the temperature guard trips, central heating and
DHW modes are interrupted.
Connecting the supply temperature sensor (e.g. for low-
loss header or system supply pipe)
Do not exceed a sensor cable length of 33 feet (10 m).
Fig. 41 Mounting supply temperature sensor right next to
boiler supply
1 System secondary line – supply pipe ≥ 1-1/2"
2 Supply temperature sensor for system supply pipe
3 Boiler primary line – supply pipe 1"
4 Boiler primary line – return pipe 1"
5 System secondary line – return pipe ≥ 1-1/2"
Fig. 42 Electrical wiring of external supply temperature
sensor
The service function 7.d connection of an external supply
temperature sensor is automatically set to 01
(Æ page 72).
6 720 641 933-91.1o
TB1
6 720 641 933-44.1O
B
B
4
2
1
F
A
LS NS
LP
NP
9
8
7
1
2
C
ϑ
Supply temperature sensor for system supply
pipe (Æ Fig. 41 [2]) must be installed in
closest vicinity with boiler supply Tee.
6 720 641 933-97.1o
ϑ
1
2
3
4
5
≤ 4"
(102 mm)
6 720 612 664-25.2O