Viessmann Vitocrossal 300 CU3A Application Manual page 57

Vitocrossal CU3A
Application 9 Operational Setup Instructions
This application consists of a mid-temperature heat circuit, a low temperature heat circuit with motorized mixing
valve, and a low temperature heat circuit with heat exchanger and mixing valve. This application is conducive to
systems in which glycol must be incorporated for safety purposes. This multi-boiler configuration offers greater
flexibility in system design as it allows for increased system turndown, boiler redundancy, increased BTU inputs,
and simultaneous operation of the heating and DHW. As the cascade control targets the maximum temperature
for the system, the mixing valves offer the added benefit of automatically adjusting the supply water temperature
regardless of the water temperatures being supplied to the other heat circuits. Since this is all controlled by the
cascade control, this makes for a simple, long lasting and efficient system. To set up this system, follow the
steps below:
Type/Option
Setup on each boiler
Setup On Cascade Control
Optional Adjustments
Set a Heating Schedule
Set a DHW Schedule
Notes/Comments
1. To enter service menu on the boiler you must hold the
"OK" and buttons for 5 seconds.
2. Setup wizard for the boilers and cascade controls must
be completed before proceeding with any additional
configurations.
3. To enter the service level of the cascade control, press
on the menu icon, select Service, and input the following
password: viservice
To proceed to level 2 coding, select system configuration
icon, select coding 2 and input the following password:
viexpert
Step# Description
1 Set to multi-boiler mode
2 Set boiler number
3 Set LON participant number
4 Set boiler pump function
5 Complete participant check
(For further instruction, refer to Installation & Service Manual)
6 Assign thermostat to HC1
7 Remove pump post purge
8 Setup HC1 outdoor reset curve
9 Setup HC2 outdoor reset curve
10 Setup HC3 outdoor reset curve
11 Adjust HC1 heating schedule
Setup
Parameter Set to:
Location
Service Function -> Select Service
Multiboiler Application Menu
07: Set Boiler #
77: Set Boiler #
Set in Level
2 Coding
37, address 8a 0
needs to be set
to 176
Service
Menu
91 :01
Set in Level
2 Coding
F2 :00
Set In
Heating Sub
Menu
--:--
Set In
Heating Sub
Menu
53