Viessmann VITODENS 100-W WB1B Series Installation And Service Instructions Manual page 42

Start-up, Inspection and Maintenance
Overview of Controls and Indicators
Fig. 44
42
(continued)
Legend
A Heating mode pump output "ON"
(when RT is closed)
B DHW mode pump output "ON"
(when DHW is closed)
C Boiler water temperature in °F or
fault code
D Units for boiler water temperature
measurement
E Service mode
F Current burner firing power rate
G Burner in operation indicator
H Fault indicator