16
6
Components
6.1.2 Combustion Air Fan
Description:
The combustion air
fan
is part of the drive
assembly (see section 6.1.1
).
It
is a ring-type blower of
high accuracy and serves to supply the combustion air
for the heater.
Check:
Check the motor speed (see section
6.1.1
).
Check
the
C02-value (see section 6.1.3).
If
the C02-value cannot be adjusted
to
the permissible
value
(10 -11% at nominal voltage), the fuel delivery
rate is
to
be
checked (see section
6.2.1
).
If
the delivery
rate is within the permissible range, the combustion air
fan
has
to
be
replaced.
Installation/Removal: as described for the drive as-
sembly (see section 6.1.1)
Adjusting procedure:
It
is not possible
to
repair the
combustion air fan. The entire drive assembly must be
replaced
as
a unit.
6.1.3 Combustion Air Adjusting Screw (Setscrew)
Description: The combustion air adjusting screw ser-
ves
to
precisely match the combustion air rate with the
fuel
rate delivered by the metering pump (C02-adjust-
ment).
Check:
The combustion air adjusting screw is of the self-lock-
ing
type. If it moves too easily, it must
be
replaced.
Co2-Adjustment: After every replacement of the drive
assembly or the metering pump, the C02-content in
the exhaust gas must be measured and readjusted, if
necessary.
CO2-Setting: If the value exceeds the permissible
functional range, the CO2-setting must be adjusted
to
10 - 11%, at rated voltage and
full
load operation,
by means of the combustion air adjusting screw.
A
screwdriver is to
be
used as tool (see Fig.).
CAUTION:
The combustion air adjusting screw is factory-set to the
specified C02-value. A correction may only be per-
formed after the metering pump or the drive assembly
has
been replaced or if the combustion air
fan
fails to
function properly.
Adjusting
procedure: Prior to measuring, allow heater
to
run
at full load for approx. 5 min. Rotation to the
right: C02-value
decreases. Rotation to the left:
Co2-
value increases.
Rough
adjustment: Screw in adjusting screw until its
upper edge is flush with the housing.
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