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 27). 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 7) (Fig. 7 on page 14). 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 returns to the 1st stage. The burner shuts down only when the boiler temperature or pressure exceeds the value set on control device TL, even if the burner 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 within the range of the values listed above the adjiacent 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 chamber in the 1st stage. MAXIMUM 2ND STAGE DELIVERY (MAX) must be selected within the range of the adjiacent 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 curv
