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

Vitocrossal 300 CU3A 26 to 57 Service

Perform Combustion Analysis

Legend
A Flue gas test port

Checking the Direct Vent (coaxial) System Tightness

Legend
A Air inlet flapper
IMPORTANT
A CO measurement (see page 25) 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 106 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 concentration of the combustion air in the coaxial
2
gap of the air intake pipe adaptor. The vent pipe is
considered sufficiently leak-proof if a CO
in the combustion air no higher than 0.2% or an O
concentration no lower than 20.6% is measured.
If higher CO values or lower O
2
check 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.
Startup
concentration
2
2
values are measured,
2
17