baltur COMIST 122 DSPGM, Instruction

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17) The air pressure switch has the job of bringing the control box to a safety shut down if the air pressure is not at
the correct value. Therefore, the air pressure switch must be regulated in such a way as to intervene by closing
the contact (foreseen to be closed while working) when the air pressure in the burner has reached a sufficient
level. The pressure switch is self-controlled and therefore it must close the contact (fan stops and consequently
there is an absence of air pressure in the burner; if it does not, the control box will not be inserted (the burner
remains at a standstill). It must be specified that if the contact is not closed during working (insufficient air
pressure), the control box will carry out its cycle, but the ignition transformer will not be inserted and the gas pilot
valves will not open. Consequently, the burner will go to “shut down”. Check that the air pressure switch functions
properly with burner at minimum delivery, increase the regulating valve until it reaches intervention point and the
burner should go to shut down. To unblock the burner, press the special pushbutton and return the pressure
switch regulator to a sufficient value in order to measure the air pressure existing during the pre-ventilation
phase.
18) The pressure switches which control the gas pressure (minimum and maximum) have the job of stopping the
burner functioning when the gas pressure is not within the values specified. From the specific functions of the
pressure switches, it is evident that the pressure switch which controls the minimum pressure must make use
of the contact, which is closed, when it measures a pressure which exceeds that at which it has been set.
The maximum pressure switch must make use of the contact, which is closed, when it measures a pressure
below that at which is has been set. The minimum and maximum gas pressure switches should be regulated
during the burner’s general inspection and should be in function with the pressure found each time.
T
he pressure switches have been electrically connected in series and therefore the intervention (by this mean
the opening of the circuit) of any one of the gas pressure switches, will prevent the control box and thus the
burner from starting up. When the burner is operating (flame lit), the intervention of the gas pressure switches
(opening of the circuit) determines the immediate arrest of the burner. During the burner’s general inspection,
check the correct functioning of the pressure switches. By operating the respective regulating device, it is
possible to control the pressure switch’s intervention (opening of circuit) which causes the burner’s arrest.
19) Check the efficiency of the flame detector “UV photoelectric Cell” sliding it put of its seat on the burner and verify
the “shut down”.
20) Check the efficiency of the thermostats and pressure switches (this should result in the burner coming to a
standstill).