Viessmann Vitocrossal 300 Series Instruction manual

Technical Data Manual
VITOCROSSAL 300
5673 647 - 14 10/2019
Model Nos. and pricing: see Price List
For operation with natural gas and liquid propane gas
Floor mounted, gas-fired condensing boiler
Heating input 19 to 199 MBH
5.6 to 58 kW
Product may not be exactly as shown
Vitocrossal 300
CU3A Series 26 to 199
Floor mounted, gas-fired condensing
boiler with modulating MatriX gas burner.
For room air dependent or independent
operation.
H

Vitocrossal 300 CU3A 26 to 199 Technical Data
5673 647 - 14
2
Product Information
2
Benefits
The benefits at a glance:
■ Best value in its class with new industry-leading
technology and the most standard features.
■ Highest Efficiency up to 98% at full modulation and up
to 95% A.F.U.E.
■ Lasting performance with industry-leading Viessmann
made SA240 316 Ti stainless steel Inox-Crossal heat
exchanger constructed to CSA B51 and ASME Section IV.
■ Low Emission Combustion with Viessmann made
stainless steel MatriX burner. Factory calibrated.
■ Fast Installation and Reduced Maintenance with
Lambda Pro, industry-first intelligent combustion
management system: Adjusts automatically to gas
type and quality. No fuel conversion kit required.
■ Powerful and User-friendly Viessmann Vitotronic on-
board multi-function outdoor reset boiler and system
control for multi-temperature space and DHW heating.
■ Zone circuit capabilities provide 3 input connections
that allow easy integration of third party components
such as thermostats, SIM controls, Multizone controllers,
and other smart or on/off control technologies.
■ The setup of these new capabilities can be done
quickly with the start-up wizard that prompts the
installer for the relevant information necessary to
setup the system without having to go into complex
levels of coding parameters.
■ The unique capability of the zone circuit control allows
the installer to combining temperature setpoint operation
and outdoor reset capability. This means that one or all
of the 3 zone circuits control can operate on a set
temperature, or vary based on the outdoor reset curve
that is selected in the start-up wizard.
Equipped with the industry’s first intelligent combustion
management system and powerful control technology,
the new generation Vitocrossal 300 CU3A gas-fired
Floor mounted condensing boiler delivers unparalleled
performance, reliability and comfort.
■ Expanded Application Range with increased capacity up
to 199 MBH (58 kW). Multi-boiler installation up to
1592 MBH (464 kW) with up to 8 boilers.
■ Greater Venting Flexibility with increased vent length
[up to 198 ft. (60 m)] and multiple venting options.
- Horizontal or vertical sealed combustion coaxial
venting (field supplied).
- Horizontal, vertical or hybrid sealed combustion
double-pipe venting (field supplied).
- Horizontal or vertical single-wall venting (field supplied).
■ Compact, Esthetic Product Design and zero clearance
to combustibles.
■ Extremely Quiet Operation; quieter than most
refrigerators.
■ True High-Altitude Operation up to 10,000 ft. (3,000 m)
with simple electronic adjustment.
■ Efficiency up to 98% through intensive condensation.
The flue gas temperature is only approximately 9ºF-27ºF
(5ºC-15ºC) above boiler return temperature.

Vitocrossal 300 CU3A 26 to 199 Technical Data
3
5673 647 - 14
Product Information
3
Cross-Section
Product may not be exactly as shown
Vitocrossal 300 CU3A 26 to 199
Vitocrossal 300 CU3A boiler efficiency dependent
on system heating water return temperatures and
load conditions
Legend
ADigital Vitotronic boiler control unit
BWater-cooled stainless steel combustion chamber
CModulating MatriX gas burner – for extremely clean
combustion
DStainless steel Inox-Crossal heat exchanger
EHighly effective thermal insulation
FFlue gas collector with condensate drain pipe
GCombustion air intake for direct vent (two-pipe)
systems

Vitocrossal 300 CU3A 26 to 199 Technical Data
5673 647 - 14
4
Technical Data
Technical Data
4
Boiler Model No. CU3A 26, 94 35, 125 45, 160 57, 199
Natural Gas / Liquid Propane Gas
CSA input
CSA output / DOE heating capacity*1
MBH
(kW)
MBH
(kW)
19-94
(5.6-27.5)
17.7-87
(5.2-25.5)
25-125
(7.3-36.6)
23.3-116
(6.8-34)
43-160
(12.6-47)
40-149
(11.7-43.7)
43-199
(12.6-58)
40-185
(11.7-54.2)
Net AHRI Rating MBH
(kW)
76
(22)
101
(30)
129
(38)
161
(47)
Heat exchanger surface area ft.2
(m2)
16.7
(1.5)
20.7
(1.9)
34.1
(3.2)
34.1
(3.2)
Min. gas supply pressure
Natural gas
Liquid propane gas
“w.c.
“w.c.
4
10
4
10
4
10
4
10
Max. gas supply pressure *3
Natural gas
Liquid propane gas
“w.c.
“w.c.
14
14
14
14
14
14
14
14
A.F.U.E. %95 95 95 95
Weight lbs
(kg)
269
(122)
275
(125)
352
(160)
352
(160)
Boiler water content USG
(L)
13.5
(51)
13.0
(49)
18.8
(71)
18.8
(71)
Max. operating pressure
at 210ºF (99ºC)
psig
(bar)
30
(2)
30
(2)
30
(2)
30
(2)
Boiler water temperature
- Adjustable high limit (AHL) range
space heating (steady state)
DHW production
- Fixed high limit (FHL)
ºF
(ºC)
ºF
(ºC)
ºF
(ºC)
68-194
(20-90)
194
(90)
210
(99)
68-194
(20-90)
194
(90)
210
(99)
68-194
(20-90)
194
(90)
210
(99)
68-194
(20-90)
194
(90)
210
(99)
Boiler connections
Boiler heating supply and return
Pressure relief valve
Boiler drain
Gas valve connection
NPTM
NPTF
NPTM
NPTF
1ain.
¾in.
1in.
¾in.
1ain.
¾in.
1in.
¾in.
1ain.
¾in.
1in.
¾in.
1ain.
¾in.
1in.
¾in.
*1 Output based on 140ºF (60ºC), 120ºF (49ºC) system supply/return temperature.
*2 Net AHRI rating based on piping and pick-up allowance of 1.15.
*3 If the gas supply pressure exceeds the maximum gas supply pressure value, a separate gas pressure regulator
must be installed upstream of the heating system.
Note: For high altitude installation at 10,000 ft. the input for model Vitocrossal 300 CU3A will have an altitude
de-ration of 18%.

Vitocrossal 300 CU3A 26 to 199 Technical Data
5
5673 647 - 14
Technical Data
5
Technical Data
Boiler Model No. CU3A 26, 94 35, 125 45, 160 57, 199
Dimensions
Overall depth
Overall width
Overall height
(with control interface open)
Overall height
inches
(mm)
inches
(mm)
inches
(mm)
inches
(mm)
27
684
26
660
67
1707
61.5
1562
27
684
26
660
67
1707
61.5
1562
31b
801
26
660
67
1707
61.5
1562
31b
801
26
660
67
1707
61.5
1562
Flue gas *4
Temperature (at boiler return
temperature of 86ºF (30ºC)
- at rated full load
- at rated partial load
Temperature (at boiler return
temperature of 140ºF (60ºC)
ºF (ºC)
ºF (ºC)
ºF (ºC)
113 (45)
90 (32)
167 (75)
113 (45)
90 (32)
167 (75)
113 (45)
90 (32)
167 (75)
113 (45)
90 (32)
167 (75)
Max. condensate flow rate *5
for NG and LPG
TS/TR=104/86ºF (40/30ºC) USG/h
(L/h)
0.9
3.43
1.2
4.62
1.6
5.95
2.1
7.92
Condensate connection hose
nozzle
Ø in. ¾¾ ¾ ¾
Boiler flue gas connection *6 Ø
in. (mm) 3 (80) 3 (80) 4 (110) 4 (110)
Combustion air supply connection outer
Ø in. (mm) 3 (80) 3 (80) 3 (80) 3 (80)
Sound Rating (A scale)
- at maximum input
- at minimum input
dB
dB
48
32
55
33
53
33
58
33
Standby losses *7BTU/hr
W/hr
1128
330
1000
292
1120
328
995
291
*4 Measured flue gas temperature with a combustion air temperature of 68°F (20°C).
*5 Based on maximum input rate.
*6 For side wall vent installations (coaxial system):
Do not exceed max. equivalent length specified in the Installation Instructions of the Vitocrossal 300 CU3A
Venting System.
Do not attempt to common-vent Vitocrossal 300 CU3A with any other appliance.
Side wall co-axial vent installation must include Viessmann protective screen!
For details refer to the Installation Instructions for the Vitocrossal 300 CU3A Venting System.
*7 Standby losses measured from the boiler temperature sensor well based on a boiler water temperature of 158°F
(70°C) and a room temperature of 68°F (20°C).
For information regarding other Viessmann System Technology componentry, please reference documentation
of respective product.

Vitocrossal 300 CU3A 26 to 199 Technical Data
5673 647 - 14
66
Dimensional Information
Models 300 CU3A 26 to 199
6
Model 26, 35, 94, 125 Model 45, 57, 160, 199
a in. (mm) 27 (684) a in. (mm) 31b(801)
b in. (mm) 17 (430) b in. (mm) 21b(545)
c in. (mm) 23b(595) c in. (mm) 28 (712)
d in. (mm) 4¾(120) d in. (mm) 5b(140)
Note: All height dimensions of the boiler have a tolerance of +.6 in. (+15 mm) due to the factory installed adjustable feet.
Legend
A Overall boiler height (boiler control open)
B Overall boiler height (boiler control closed)
C Safety header connection
D Boiler supply
E Gas connection
F Boiler return
G Boiler drain
H Vent connection
I Condensate drain connection
J Combustion air connection

Vitocrossal 300 CU3A 26 to 199 Technical Data
7
5673 647 - 14
Minimum Clearances
7
Recommended Minimum Service Clearances
Note: The Vitocrossal 300 CU3A series boiler conforms
to the zero inches vent clearance to combustibles
testing requirements dictated by the boiler
Harmonized Standard ANSI Z21.13. CSA/4.9
(latest edition) and therefore is listed for zero
clearance to combustibles when vented with a
single-wall UL/ULC certified special venting system.
The zero inches vent clearance to combustibles for
the Vitocrossal 300 CU3A boiler supercedes the
clearance to combustibles listing that appears
on the special venting system label.
The back or side clearance shall be increased if
piping installation is required.
See the Vitocrossal 300 CU3A Venting
System Installation Instructions for details.
Recommended minimum service clearances
For typical Vitocrossal CU3A series boiler installations,
Viessmann recommends installing the boiler with the
service clearances shown in the illustration.
The Vitocrossal CU3A series boilers are approved for
closet and alcove installation with the clearances to
combustibles listed.
Boiler model CU3A 26, 94 35, 125 45, 160 57, 199
Top 0000
Sides (left and right) 0000
Vent pipe 0000
Front (alcove or closet) 0000
Rear 0000
Floor combustible combustible combustible combustible
Minimum clearances to combustibles
1*
*1 Clearance between boilers may be reduced to zero
in multi-boiler installations.
Note: The burner, boiler control, condensate trap,
venting and heat exchanger are still fully
accessible from the front and rear of the boiler.

Vitocrossal 300 CU3A 26 to 199 Technical Data
5673 647 - 14
8
Waterside Flow
Pressure Drop (heating water side)
Legend
ABoiler models CU3A 26, 35, 94, 125
BBoiler models CU3A 45, 57, 160, 199
The Vitocrossal 300 is only suitable for fully pumped hot
water heating systems.
Boiler models CU3A
∆T = 20ºF (10 K) ∆T = 30ºF (15 K) ∆T = 40ºF (20 K)
Flow rate
USGPM (m3/h)
Flow rate
USGPM (m3/h)
Flow rate
USGPM (m3/h)
26, 94 9.9 (2.2) 6.6 (1.5) 4.9 (1.1)
35, 125 13.3 (3.0) 8.9 (2.0) 6.6 (1.5)
45, 160 17.0 (3.9) 11.4 (2.6) 8.5 (2.0)
57, 199 22.7 (5.2) 15.0 (3.4) 11.4 (2.6)
Pressure drop
Flow rate
Note: This boiler does not require a flow switch.

Vitocrossal 300 CU3A 26 to 199 Technical Data
9
5673 647 - 14
Boiler Control
On-Board Vitotronic 200, HO1B Control
Modular structure
The control unit is integrated into the boiler. The control
unit comprises a standard unit, electronics modules and
a programming unit.
Standard unit:
■ON/OFF switch
■Optolink laptop interface
■Operating and fault indicators
■Reset button
■ Fuses
Programming unit:
■Easy operation through:
– Plain text display with graphic ability
– Large font and black & white depiction for good
contrast
– Context-sensitive help text
– Removable programming unit; can be mounted
on the wall with separate accessory
■With digital time switch
■Control keys for:
– Navigation
– Confirmation
– Help and additional information
– Menu
■Setting the:
– Room temperature
– Reduced room temperature
– DHW temperature
– Heating program
– Time programs for central heating, DHW heating
and DHW recirculation
– Economy mode
– Party mode
– Holiday program
– Heating curves
– Codes
– Actuator tests
– Test mode
■Displaying the:
– Boiler water temperature
– DHW temperature
– Operating details
– Diagnostic details
– Fault messages
Zone control interface
Heating circuit interface

Vitocrossal 300 CU3A 26 to 199 Technical Data
5673 647 - 14
10
Frost protection
■The frost protection function will be started when the
outside temperature drops below approx. 34°F (1°C).
With the frost protection function, the heating circuit
pump will be switched ON and the boiler water is
maintained at a lower temperature of approx. 68°F
(20°C).
The DHW tank will be heated to approx. 68°F (20°C).
■The frost protection function will be stopped when the
outside temperature rises above approx. 37°F (3°C)
(default settings).
Summer Operation
Heating program “w”
The burner is only activated upon a call for domestic hot
water from the DHW storage tank (controlled by DHW
tank temperature sensor).
Design and Function
Boiler Control
Control Characteristics
PI characteristics with modulating output.
Time Switch
Digital time switch.
■Individual and 7-day program
■Automatic daylight savings time changeover
■Automatic function for DHW heating and DHW
recirculation pump
■Time, day and standard switching times for space
heating, DHW heating and the DHW recirculation
pump are factory-set
■Switching times are individually programmable,
i.e. up to four switching periods per day
Shortest switching interval: 10 minutes
Power backup: 14 days.
Functions
■Weather-compensated control of the boiler water
and/or supply temperature
■Control of one heating circuit without mixer and two
heating circuits with mixer (with accessory mixing
valve extension modules)
■Demand-dependent heating circuit pump and burner
off control
■Adjustment of a variable heating limit
■Anti-seizing pump protection
■Integral diagnostic system
■Maintenance display
■DHW temperature control with priority
■Auxiliary function for DHW heating (short-term
heating to a higher temperature)
■0-10V External signal input
■0-10V Pump speed control output signal
Setting the Operating Programs
The heating system frost protection (see
frost protection function) applies to all heating programs.
You can select the following heating programs with the
program keys:
■Heating and DHW
■DHW only
■Standby mode
■Zone circuits (dry contact) thermostat
External heating program changeover.