Viessmann Vitodens 200 Service Manual page 16

Further details regarding the individual steps
Leak testing the BF system (checking the circular gap)
For balanced flue systems tested together with the gas-fired wall-mounted
boilers, some Federal States (e.g. Nordrhein Westfalia) waive the leak test
(overpressure test) during commissioning by the district chimney sweep.
We recommend that your heating engineer carries out a simple leak test
during the initial start-up of your system. It would be sufficient to check the
CO concentration in the combustion air at the annular gap in the BF line.
2
The flue pipe is deemed to be sufficiently tight if the CO concentration in the
2
combustion air is a maximum of 0.2 % and the O concentration is a minimum
2
of 20.6 %.
If actual CO values are higher or O values are lower, then you must test the
2 2
flue pipe for leaks at a static overpressure of 200 Pa.
A
A
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