PART III: OPERATION
26
5.3 Fully-modulating burners
.To adjust the fully-modulating burners, use the
CMF
switch on the burner control panel (see next picture), instead of the
TAB
thermo-
stat as described on the previous paragraphs about the progressive burners. Go on adjusting the burner as described before, paying
attention to use the CMF switch intead of
TAB
.
The
CMF
position sets the oprating stages: to drive the burner to the high-flame stage, set CMF=1; to drive it to the low-flame stage, set
CMF=2.
5.4 Gas valves Siemens VGD - Version with SKP2. (provided with pressure stabilizer).
5.5 Setting air and gas pressure switches
The
air pressure switch
locks the control box if the air pressure is not the one requested. If it
happens, unlock the burner by means of the control box unlock pushbutton, placed on the
burner control panel.
The
gas pressure switches
check the pressure to avoid the burner operate when the pres-
sure value is not in the requested pressure range.
5.6 Calibration of low gas pressure switch
As for the gas pressure switch calibration, proceed as follows:
z
Be sure that the filter is clean.
z
Remove the transparent plastic cap.
z
While the burner is operating at the maximum output, test the gas pressure on the pressure port of the minimum gas pressure
switch.
z
Slowly close the manual cutoff valve (placed upstream the pressure switch, see gas train installation diagram), until the detected
pressure is reduced by 50%. Pay attention that the CO value in the flue gas does not increase: if the CO values are higher than the
limits laid down by law, slowly open the cutoff valve as to get values lower than these limits.
z
Check that the burner is operating correctly.
z
Clockwise turn the pressure switch adjusting ring nut (as to increase the pressure value) until the burner stops.
z
Slowly fully open the manual cutoff valve.
z
Refit the transparent plastic cover on the pressure switch.
5.7 Adjusting the maximum gas pressure switch (when provided)
To calibrate the maximum pressure switch, proceed as follows according to its mounting position:
1
remove the pressure switch plastic cover;
CMF = 0 stop at the current position
CMF = 1 high flame operation
CMF = 2 low flame operation
CMF = 3 automatic operation
To increase or decrease gas pressure, and therefore gas flow rate, remove the cap
T
and use a screwdriver to adjust the regulating screw
VR
. Turn clockwise to increase
the flow rate, counterclockwise to reduce it.
CMF
VR
T
VR
