Installing A Low Water Cut Off (Lwco) - Bosch ZBR16-3A Installation And Service Instructions Manual

42 | Installation
5.7

Installing a low water cut off (LWCO)

The boiler is equipped with several sensors that prevent
firing or running the boiler in case of low water pressure or
low water levels. Nevertheless code may require the
installation of a separate low water cut off (LWCO).
The boiler is equipped with a dedicated port for
installation of a LWCO on the supply pipe inside the boiler
cabinet. This location represents the minimum water level
for safe operation of the boiler.
The LWCO device must be specified for an ambient
temperature of 176 °F (80 °C) and a water temperature of
250 °F (121 °C). It needs a dry contact.
The following LWCO is approved with the boiler:
• Hydrolevel Safgard 1100
The device is available at most Bosch wholesalers.
It requires an external 24VAC 20VA transformer provided
on site.
If other LWCO devices are to be used, they
must be installed external to the boiler.
The Hydrolevel Safgard 1100 is installed in the supply pipe
to the left of the heat exchanger.
B Disconnect the boiler from power by shutting off the
emergency shutoff switch or disengaging the heating
system circuit breaker.
B Drain the boiler.
B Remove the safety clip from the dummy plug in the
supply pipe (step 1).
B Pull off the dummy plug (step 2) and place with the
boiler documentation.
B Ensure the O-ring remains in place on the pipe.
B Lubricate the O-ring.
Fig. 19 Installing a LWCO device - removing dummy plug
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B Screw the LWCO as far as possible into LWCO adapter
located in the boiler accessory kit. Follow the
Hydrolevel Safgard 1100 instructions.
Fig. 20 Installing a LWCO device - LWCO adapter
B Push the adapter with the LWCO onto the pipe (step 1)
and secure with the clip (step 2).
Fig. 21 Installing a LWCO device – securing with a clip
B Connect the wires of the LWCO (
page 57).
The LWCO is positioned upright for technical
reasons. Tests have shown that all air will
bleed from the pipe during commissioning
and full functionality is established.
If fault d3 is displayed when commissioning
the boiler, purge the boiler properly and check
the boiler water pressure.
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chapter 6.4,
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