Connections; Connecting Power; Connecting Heating System; Proper Piping Practice - Viessmann Vitocrossal 300 CU3A 26 Installation Instructions Manual

Vitocrossal 300 CU3A 26 to 199 Installation

Connections

rear view
Legend
A Safety connection
(pressure relief valve and air vent valve) 1a in. NPT
B Boiler supply 1a in. NPT
C Boiler return 1a in. NPT
D Condensate drain Ø ¾ in. (19 mm) barbed fitting
E Safety return and drain (diaphragm expansion vessel)
1 in. NPT
F Gas connection ¾ in. NPT
G Boiler flue termination
H Combustion air intake
Note: The Vitocrossal is only suitable for fully pumped
hot water heating systems. Never install 4-way
mixing valves, overflow valves or other flow/return
bypass devices. Never connect a heating return
to the safety return.
CAUTION
To prevent equipment damage, install all pipework
free of load and torque stresses.

Connecting power

The Vitocrossal 300 CU3A boiler has external accessories
connection modules installed behind the front cover,
which requires a 120VAC power supply from a wall
receptacle. Refer to the wiring diagram (see page 57).

Connecting heating system

Flush heating system thoroughly prior to connecting boiler

Proper piping practice

Support piping by proper suspension method. Piping
must not rest on or be supported by boiler. Use moderate
amount of dope.
Use an approved pipe sealant or teflon tape when
connecting the following installation fittings.
2 imperfect threads
Boiler Connections
Leave 2 threads bare
11