Viessmann CU3, Service Instructions Manual

Page: 14 / 56

14
Initial start−up, inspection and maintenance
Further details regarding the individual steps
(cont.)
Leak testing the balanced flue system (annular gap check)
For balanced flue systems tested together with a gas fired boiler, some
Federal States (e.g. North Rhine Westphalia) waive the leak test (overpressure
test) during commissioning by the flue gas inspector.
We recommend that your heating engineer carries out a simple leak test
during the initial start−up of your system. For this it would be sufficient to
check the CO
2
concentration in the combustion air at the annular gap in the
balanced flue pipe.
The flue pipe is deemed to be sound if the CO
2
concentration in the
combustion air is lower than 0.2 % or if the O
2
concentration is at least 20.6 %.
If actual CO
2
values are higher or O
2
values are lower, then pressure check the
flue pipe at a static pressure of 200Pa.
For location of combustion air test nipple
B
(ventilation air), see the diagram
on page12.
Checking ionisation current
5692500GB
C D
B
A