Adjusting Air And Gas Flow Rates; Adjustments - Brief Description; Adjustment Procedure - Unigas RX90 Installation Manual

Adjusting air and gas flow rates

ATTENTION: before starting the burner up, be sure that the manual cutoff valves are open and check that the pres-
sure upstream the gas train complies the value quoted on paragraph "Technical specifications". Be sure that the
mains switch is closed.
.ATTENTION: During commissioning operations, do not let the burner operate with insufficient air flow (danger of formation
of carbon monoxide); if this should happen, make the gas decrease slowly until the normal combustion values are achieved.
WARNING: NEVER LOOSE THE SEALED SCREWS! OTHERWISE, THE DEVICE WARRANTY WILL BE IMMEDIA-
TELY INVALIDATE!
IMPORTANT! the combustion air excess must be adjusted according to the suggested values in the following
chart:

Adjustments - brief description

Adjust the air and gas flow rates at the maximum output ("high flame") first, by means of the air damper and the adjusting cam respec-
tively.
Check that the combustion parameters are in the suggested limits.

Check the flow rate measuring it on the counter or, if it was not possible, verifying the combustion head pressure by means of a dif-

ferential pressure gauge, as described on page 28.
Then, adjust the combustion values corresponding to the points between maximum and minimum: set the shape of the adjusting

cam foil. The adjusting cam sets the air/gas ratio in those points, regulating the opening-closing of the throttle gas valve.
Set, now, the low flame output, acting on the low flame microswitch of the actuator in order to avoid the low flame output increasing

too much or that the flues temperature gets too low to cause condensation in the chimney.

Adjustment procedure

To change the burner setting during the testing in the plant, follow the next procedure.
On the DUNGS MBC..SE gas valves group, set the pressure regulator to 1/3 of its stroke, using a 2.5 allen key.
Now, adjust the burner according to the actuator model provided.
Recommended combustion parameters
Recommended (%) CO
Fuel
Natural gas
Recommended (%) O
2
9 ÷ 10
31
2
3 ÷ 4.8
Pressure setting