Applicability; Product Information - Viessmann VITOCROSSAL 300 Installation Instructions Manual

General Information

Applicability

CAUTION
The boiler serial number must be provided when ordering
replacement parts.
IMPORTANT
When ordering replacement parts, provide either the
16-digit boiler serial number (on the bar code label)
located underneath boiler front enclosure panel.
Refer to page 21 for instructions on how to remove
front enclosure panel.
Model No. CU3A 26
Serial No. 7553000jjjjjjjjj
Model No. CU3A 35
Serial No. 7553001jjjjjjjjj
Model No. CU3A 45
Serial No. 7553002jjjjjjjjj
Model No. CU3A 57
Serial No. 7553003jjjjjjjjj
Legend
A Digital Vitotronic boiler control unit
B Water-cooled stainless steel combustion chamber
C Modulating MatriX gas burner – for extremely clean
combustion
D Stainless steel Inox-Crossal heat exchanger
E Highly effective thermal insulation
F Flue gas collector with condensate drain pipe
G Combustion air intake for direct vent (two-pipe)
systems

Product Information

Natural gas and liquid propane gas-fired condensing
heating boiler for weather-responsive operation in closed
loop, forced circulation hot water heating systems for
space heating and domestic hot water (DHW) production.
The Vitocrossal CU3A series boiler comes factory
set for operation with natural gas. For a fuel conversion
to liquid propane gas no conversion kit is required.
Boiler model must be selected based on an accurate heat
loss calculation of the building. Ensure boiler model is
compatible with connected radiation.
Vitocrossal CU3A series boilers are factory-tested and
calibrated. Further gas valve adjustments are not typically
required during field start-up.
8
Vitocrossal 300 CU3A 26 to 57 Installation
Follow the Vitocrossal CU3A Venting System
Installation Instructions to vent this boiler.
For conversion to LPG refer to the Service
Instructions.