Viessmann Vitocrossal 300 CA3 2.5 Installation And Service Instructions Manual page 52

Installation
Gas Connections
52
(continued)
Vitocrossal 300 CA3 Series 2.5 to 6.0 Installation/Service
The gas line on the burner meets the requirements
of ASME/CSD-1.
1. Connect gas pipe A to the gas valve.
Gas connection:
Vitocrossal 300, CA3: 2b in. NPT for models 2.5, 3.0,
3.5 and 4.0, 3 in. NPT for models 5.0 and 6.0.
Note: Gas line weld nipples are available as an
accessory kit.
For more information refer to the Installation
Instructions for gas line weld nipples.
2. Test leak tightness of gas pipe connection using an
approved method.
3. Purge gas line in a safe manner using an approved purge
burner.
WARNING
If test pressure is too high burner and gas fittings
may get damaged.
WARNING
Escaped gas may lead to explosion, which could
cause severe injuries. Do not vent gas pipe above
combustion chamber of boiler.
CAUTION
If gas pipe contains dirt it is recommended to install
a gas filter into the gas pipe.
Vitocrossal fuel supply recommendations
- Always read and follow the instructions provided with
the gas pressure regulator.
- Install high pressure regulator a minimum of 10 ft. (3.3 m)
upsteam of the boiler fuel connection.
- Install one gas pressure regulator per boiler.
- Use a gas pressure regualtor with an outlet size equal to
the boiler fuel connection, if a change in pipe diameter is
required a concentric reducing coupling should be used.