Description of functioning
t e c h n i c a l
21
3.1.4- Air Circuit
Characteristics of the air circuit components:
Fan:
(Part number MCB2030)
The function of the fan is to
draw
in air from the outside and evacuate the burnt gases
produced during combustion
.The 24kW boiler fan has a power of 35W.
Part number MCB2030
Air pressure switch:
(Part numberMCB2105)
This component ensures that the fan is running, that there are
no obstructions anywhere in the
flue or in the flue venturi, also
checks that the flue is
install
ed and working correctly
24kW boiler -> 140/89Pa pressure switch
If a pressure switch is calibrated to 140/89 Pa, for example, this means that the pres-
sure switch contacts are activated at a differential pressure of 140Pa (1
.
4
mb
) and
deactivated at 89Pa (
.
89 m
b
).
To measure the differential pressure, fi rst measure the pressure using the water co-
lumn in one of the Venturi gauges, and then with the water column in the other. The
result will be the sum total of both.
This data is to be taken as an approximate value only, as variations of a few Pascals
occur in the measur
e
ments while the fan is running.
Flue
Venturi :
(Part number MCB2100)
This is fi tted to the
fan
outlet pipe. When the
air or flue gases
fl ow through it, a pressure difference is produced which must
be great enough to activate the differential air pressure switch
.
PLEASE NOTE THAT DURING PERIODS OF SHUT DOWN. THE
FLUE VENTURI MAY BECOME BLOCKED WITH INSECTS.
IT WILL BE NECESSARY TO REMOVE AND CLEAN THE VENTURI..
THE VENTURI WILL ONLY FUNCTION CORRECTLY WHEN FITTED
WITH THE LONGEST PART FACING UPWARDS(- TO TOP)
+
-
MCB2105
18
