M039150CF
24
ADJUSTEMENTS
Combustion head gas pressure curves depending on the flow rate
Curves are referred to pressure = 0mbar in the combustion head!
The curves referred to the gas pressure in the combustion head, depending on the gas flow rate, are referred to the burner properly
adjusted (percentage of residual O
2
in the flues as shown in the “Recommended combustion values” table and CO in the standard
limits). During this stage, the combustion head, the gas butterfly valve and the actuator are at the maximum opening. Refer to Fig. 22,
showing the correct way to measure the gas pressure, considering the values of pressure in combustion chamber, surveyed by means
of the pressure gauge or taken from the boiler’s Technical specifications.
Fig. 22
Key
1
Generator
2
Pressure outlet on the combustion chamber
3
Gas pressure outlet on the butterfly valve
4
Differential pressure gauge
Measuring the gas pressure in the combustion head
In order to measure the pressure in the combustion head, insert the pressure gauge probes: one into the combustion chamber’s pres-
sure outlet to get the pressure in the combustion chamber and the other one into the butterfly valve’s pressure outlet of the burner. On
the basis of the measured differential pressure, it is possible to get the maximum flow rate: in the pressure - rate curves (showed on the
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 fuel decrease slowly until the normal combustion values are achieved.
WARNING: NEVER LOOSE THE SEALED SCREWS! OTHERWISE, THE DEVICE WARRANTY WILL BE INVALIDATE!
ATTENTION! before starting the burner up, make sure that the return pipe to the tank is not obstructed. Any
obstruction would cause the pump seal to break.
IMPORTANT! the combustion air excess must be adjusted according to the in the following chart:
Recommended combustion parameters
Fuel
Recommended (%) CO
2
Recommended (%) O
2
Natural gas
9 ÷ 10
3 ÷ 4.8
Light oil
11.5 ÷ 13
2.9 ÷ 4.9
1
2
4
3
