20140894
10
GB
Technical description of the burner
4.6
Firing rates
The PRESS G Model burners can work in two ways: one-stage
and two-stage.
In one-stage operation, only one control device is provided: TL
(See the wiring diagram on page 26).
The burner fires in the 1st stage, where it remains for 7 seconds
before passing to the 2nd stage when commanded by the control
box 8) (Fig. 7 on page 13).
When the boiler temperature or pressure exceeds the values set
on the control device TL, the burner shuts down.
In two-stage operation, two control devices are provided: TL and
TR.
The burner fires in the 1st stage but passes to the 2nd stage only
if control device TR is closed. Once the temperature or pressure
value set on control device TR has been reached, the burner re-
turns to the 1st stage.
The burner shuts down only when the boiler temperature or pres-
sure exceeds the value set on control device TL, even if the burn-
er is still operating in the 1st stage.
Two-stage operation ensures reduced boiler temperature or
pressure fluctuation and consequently lower operating costs.
MINIMUM 1ST STAGE DELIVERY (MIN)
must be selected with-
in the range of the values listed above the adjacent diagrams.
Example:
for the PRESS 1G Model, the selection may range from 11 - 22.5
kg/h.
It is not necessary to know the pressure in the combustion cham-
ber in the 1st stage.
MAXIMUM 2ND STAGE DELIVERY (MAX)
must be selected
within the range of the adjacent diagrams. This area is known as
the FIRING RATE and provides the maximum delivery of the
burner according to the combustion chamber pressure.
Example:
for the PRESS 1G Model, this area is delimited by:
–
the 16 - 45 kg/h delivery line
–
the 0 +6,5 mbar combustion chamber pressure line
–
the combustion chamber maximum pressure curve.
The work point may be found by plotting a vertical line from the
desired delivery and a horizontal line from the pressure in the
combustion chamber. The intersection of these two lines is the
work point which must lie within the FIRING RATE area.
Example:
if the PRESS 1G Model has a delivery of 30 kg/h at a combustion
chamber pressure of 4 mbar, the work point will be found on the
maximum pressure curve.
Consult page 11, for operation at different surrounding tempera-
tures and/or altitudes.
The delivery of the burner to be coupled to the boiler must be se-
lected in the MAX. area - in other words, within the FIRING
RATE.
The burner can also operate in depression combustion cham-
bers.
WARNING
The firing rate value (Fig. 3) has been obtained
considering an ambient temperature of 20 °C, an
atmospheric pressure of 1013 mbar (approx. 0 m
above sea level), and with the combustion head
adjusted as shown on page 31.
Fig. 3
kg/h
PRESS 1G - MIN
(1st stage) = 11 - 22,5 kg/h
D392
MAX
PRESS 2G - MIN
(1st stage) = 18 - 30 kg/h
kg/h
D393
MAX
PRESS 3G - MIN
(1st stage) = 23 - 50 kg/h
D394
kg/h
MAX
D395
PRESS 4G - MIN
(1st stage) = 35 - 70 kg/h
kg/h
MAX
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Summary of Contents for PRESS 1G
Page 2: ......
