42
Figure 36 -
Combustion air pressure probes
Figure 37 -
Checking the combustion air pressure
11.8 - Check the
combustion air pressure
The boiler has a factory-set air/gas ratio. The pressure
of the gas at the burner is indirectly controlled by the
blower. The combustion
air pressure is checked inside
the boiler and must correspond with that shown in the
table in section 14 under the item “combustion
air
pressure”. To carry out the check, proceed as follows
while refering to figures 36 and 37:
use a differential manometer with a precision of at
least 0.1 in.W.C.
(
0.25 mbar)
;
close the manual gas shut off valve, figure 16 and
17 item “3”;
open the boiler casing following section 13.2 or
13.3;
press the two plastic spring tabs labeled “B” shown
in figure 18 and rotate the electrical box;
remove plug “B”;
turn pressure probe screw “C” one turn
counterclockwise;
insert tube “F”, from the negative side of the
manometer, through the opening of plug “B”, and
connect it to pressure probe “C” as shown in figure
37;
remove plug “A” from the pressure probe and
connect the differential positive side of the
manometer to it;
the manometer connections must be made as
shown in figure 37, to get the correct pressure
reading;
replace panel “H” of figure 44 and latch it closed. If
panel “H” is not properly in place the manometer
reading will not be accurate;
turn the power switch to on, item “34” in figure 1;
press the
and
keys together for more
than 10 seconds, until a blinking
is
displayed;
the combustion blower will run at maximum speed
for 10 minutes. During this time the burner will not
light;
compare the pressure on the manometer with the
table in section 14, “Combustion air pressure”. The
combustion air pressure reading should be within
±
0.3 in.W.C.
(0.75 mbar)
;
if the combustion air pressure is too low, check that
there are no obstructions in the combustion air and
vent systems. Also make sure that panel “H” is
properly sealed;
if the combustion air pressure is within tolerance
press the
button to return the boiler to its
normal running mode;
once the combustion air pressure check has been
performed, reassemble everything as it was
originally.
11 - OPERATING
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