AIR PRESSURE SWITCH
FUNCTIONAL DESCRIPTION
The air pressure switch is used to lock the equipment if air pressure
is not at the expected value. The pressure switch must be set to
trigger when the air pressure in the burner does not reach the
sufficient value.
To ensure the air pressure switch correct operation, with burner at
the minimum output, increase the adjustment value until reaching
the triggering value which must be followed by the immediate burner
shut-down. Press the release button to resume the burner operation,
and set the pressure switch to a sufficient value to detect the air
pressure during the first phase of pre-ventilation.
GAS PRESSURE SWITCH
FUNCTIONAL DESCRIPTION
The gas pressure switches (minimum and maximum) prevent
the burner from operating when gas pressure is not between the
expected range. The specific function of the pressure switches
clearly reveals that the pressure switch for controlling minimum
pressure uses the NO (normally open) contact which closes when
the pressure switch detects a pressure value above the value it is set
to, while the pressure switch for controlling maximum pressure uses
the NC (normally closed) contact that is closed when the pressure
switch detects a pressure lower than the value it is set to. The
minimum and maximum gas pressure switches must be set when
testing the burner, on the basis of the pressure measured in each
case. The pressure switches are connected in a way in which the
triggering (i.e. circuit opening) of the pressure switch controlling the
maximum pressure produces the immediate locking of the burner;
whereas, when the pressure switch controlling the minimum pressure
is triggered, the burner stops and remains in the stand-by status until
the pressure within the values needed for the operation is restored.
After that, the burner re-starts in an autonomous way following the
ignition sequence.
Regulation prior to burner ignition: regulate the pressure switch for
minimum pressure at the minimum value of the scale, regulate the
pressure switch for the maximum value at the maximum value of
the scale. Regulation after the burner regulation : With the burner
at the maximum delivery, regulate the pressure switch for minimum
pressure by increasing the regulation value until the burner shuts
down, read the value on the regulation ferrule and set it to a value
diminished by 5 mbar. With the burner at the minimum delivery,
regulate the pressure switch for maximum pressure, diminishing the
regulation value until the NC (normally closed) contact opens. Read
the value on the regulation ferrule and set it to a value increased
by 5 mbar.
in case only one pressure switch is installed on the gas trainit
must be a pressure switch for minimum pressure.
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