Viessmann B2HF - Information on Replacing the HMU Heat Management Unit and BCU Burner Control Unit; Replacing the Power Cable; Replacing the HMI Connecting Cable; Checking the Plate Heat Exchanger

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Information on replacing the HMU heat management unit and BCU burner control unit
If BCU burner control units and/or HMU heat manage-
ment unit are replaced, the replacement must be car-
ried out with the help of the "service assistant".
See spare part installation instructions and inter-
net address: "www.service-assistent.info"
Replacing the power cable
When replacing the power cable, only use the power
cable available as a spare part from Viessmann.
Replacing the HMI connecting cable
!
Please note
Incorrect routing of the cable can lead to heat
damage and impairment of the EMC properties.
For positioning and securing of the cable (fixing
point of the cable tie) see connecting cable
installation instructions.
Checking the plate heat exchanger
8.
3.
2.
8.4.
D
A B
C
Fig. 55
A
Heating water flow
B
Heating water return
C
Cold water
D
DHW
1. Shut off and drain the boiler on the heating water
and DHW sides.
2. Undo screws.
Troubleshooting
Repairs (cont.)
5593201
Diagnosis