Viessmann Vitocrossal 300 CA3 2.5 Installation And Service Instructions Manual page 16

Installation
Boiler Connections
Legend
A Boiler supply
B Temperature/pressure gauge
C Pressure relief valve
D Boiler return
E Drain valve
F Precharged expansion tank
G Automatic fill
H Condensing water drain
I Flue gas test port
16
(continued)
Vitocrossal 300 CA3 Series 2.5 to 6.0 Installation/Service
All Vitocrossal 300 boilers are hydrostatically factory
tested to ASME requirements.
Safety Header
CAUTION
Do not connect heating system to safety header.
1. Locate safety header on the main supply header.
Max. allowable working pressure (MAWP) .... 160 psi (11 bar)
Min. water pressure: 8 psi (0.5 bar)
Note: The minimum water pressure is necessary for safe
operation.
Note: All boilers must have a pressure relief valve.
WARNING
Exposing the boiler to pressures and temperatures in
excess of those listed will result in damages, and will
render warranty null and void.
Note: Make all connections free of load and torque stresses.