Perform Combustion Analysis; Checking The Direct Vent (Coaxial) System Tightness - Viessmann Vitocrossal 300 Series Service Instructions Manual

Start-up

Perform Combustion Analysis

Legend
A Flue gas test port

Checking the Direct Vent (coaxial) System Tightness

Legend
A Air inlet flapper
20
Vitocrossal 300 CU3A 26 to 199 Service
IMPORTANT
A CO measurement (see page 28) must be taken before
2
and after working on gas appliances to eliminate risks to
health and to guarantee the satisfactory condition of the
system.
Record the measured combustion values in the sequence
stated in the Maintenance Record on page 113 in this
manual.
Viessmann strongly recommends that the heating contractor
perform a simplified leak test during boiler start-up. For this
purpose it is sufficient to measure the CO
the combustion air in the coaxial gap of the air intake adaptor.
The vent pipe is considered sufficiently leak-proof if a CO
concentration in the combustion air no higher than 0.2% or
an O concentration no lower than 20.6% is measured.
2
If higher CO values or lower O
2
venting system thoroughly.
Note: This measurement can be taken at the flapper A
located on the air inlet pipe located just prior to
the burner.
concentration of
2
2
values are measured, check
2