Viessmann WB1A Series Installation And Service Instructions Manual page 49

Steps
(continued)
S
Start-up and Maintenance
ervice
Legend
Inlet gas pressure measurement
port
Outlet pressure port (connected to
differential pressure switch)
Do not remove this screw or
attempt to make any adjustment
with inside screw
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5. How the Vitodens 100-W boiler operates...
The Vitodens 100-W boiler uses a premix combustion system, which is designed
to deliver a measured air-gas mixture to the burner for complete combustion. The
gas is injected upstream of the blower. The burner and heat exchanger are part of
a forced-draft design. The benefits of forced-draft systems are lower component
temperatures, direct air-fuel connection (premix) for improved mixing, and longer
service life of the boiler due to mild to moderate ambient conditions.
The cylinder burner blower and the combination gas valve are factory calibrated
and pre-adjusted for optimum boiler performance at all firing rates through a
pneumatic link between combustion air and gas flows. Blower speed is
automatically increased or decreased based on heat demand, thereby regulating
the amount of combustion air drawn. The pneumatic link between air and gas
introduces the required amount of gas for correct combustion to meet the current
heat demand, based on a linear relationship between ∆ ∆ ∆ ∆ P air and ∆ ∆ ∆ ∆ P gas.
Initial Start-up, Inspection and Maintenance
WARNING
FOR FACTORY CALIBRATING
PURPOSES, THE COMBINATION GAS
VALVE IS EQUIPPED WITH
ADJUSTMENT SCREW "C".
DO NOT ATTEMPT TO ADJUST OR
READJUST THESE SCREWS.
ANY ATTEMPT TO TAMPER WITH
FACTORY PRE-ADJUSTED SETTINGS
WILL LEAD TO UNSTABLE OPERATION
AND WILL AFFECT BOILER
WARRANTY.
49