Bosch ZBR 28-3 A NG User Manual

Notes on installation and operation
Greenstar – 6721822579 (2021/01)
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6.7 Installing the 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 AC 20VA transformer provided on site.
When a different LWCO is used, it must be installed outside the wall-
mounted gas condensing boiler.
The Hydrolevel Safgard 1100 is installed in the supply pipe to the left of
the heat exchanger.
▶ Disconnect the boiler from power by shutting off the emergency
shutoff switch or disengaging the heating system circuit breaker.
▶Drain the boiler.
▶ Remove the safety clip from the dummy plug in the supply pipe
(step 1).
▶ Pull off the dummy plug (step 2) and place with the boiler
documentation.
▶ Ensure the O-ring remains in place on the pipe.
▶ Lubricate the O-ring.
Fig. 23 Installing a LWCO device - removing dummy plug
▶ Screw the LWCO as far as possible into LWCO adapter located in the
boiler accessory kit. Follow the Hydrolevel Safgard 1100
instructions.
Fig. 24 Installing a LWCO device - LWCO adapter
▶ Push the adapter with the LWCO onto the pipe (step 1) and secure
with the clip (step 2).
Fig. 25 Installing a LWCO devicesecuring with a clip
▶ Connect the wires of the LWCO ( chapter 49, page 7.4).
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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Bosch ZBR 28-3 A NG Specifications

General

Brand	Bosch
Model	ZBR 28-3 A NG
Category	Boiler
Language	English