Installation manual

38
3.3.1 Measurement and adjustment of percentage of CO2. per MERIDIAN 5.24 e 5.32
(valve system + mixer Honeywell)
To set the CO
2
value, do the following:
♦ Remove the front cover of the boiler;
♦ Turn the boiler control
panel and unscrew the two
side screws that hold it in
place.
♦ Move the boiler
selector to “Chimney
sweep”, a
function which
appears on the display
with a “spanner” symbol
and then set the heating
potentiometer to
maximum.
♦ With the boiler burner
on, reset the function
selector.
♦ Display the fan rpm by quickly turning the sanitary knob. Behind the control panel, use
a small slotted screwdriver to adjust the number of fan rpm on trimmer P4 as indicated
in Table 5 on page 28. Information appears on the front of the display where the two
large digits on the left 54) indicate the hundreds and thousands and the two small digits
on the right 53) indicate the units and tenths. (see Figure 17).
♦ Place the combustion control sensor in the flue gas sampling connection and measure
the percentage of CO
2
;
♦ If necessary, adjust the value (see Table 6) by turning the Venturi screw (B) as shown
in Fig. 16 using a 4mm Allen spanner.
♦ Turn anti-clockwise to increase the percentage of CO2;
♦ Turn clockwise to decrease the percentage of CO2;
⇒ adjust by turning the screw only 1/8 turn and waiting for at least 1 minute after every
turn for the value to stabilise;
⇒ Proceed as follows to check the setting at minimum capacity:
⇒ switch the heating potentiometer to minimum; the boiler is now operating at
minimum power
⇒ Adjust the fan rpm to the minimum power using trimmer P2 on the boiler PCB. The
rpm are displayed on the front display as shown above when adjusting the fan
speed at maximum power.
⇒ if necessary turn the off-set screw (A) of the gas valve clockwise to increase the
percentage of CO2, or anti-clockwise to decrease it;
♦ Check the percentage of CO
2
by operating the boiler at maximum capacity (heating
potentiometer turned to maximum) and then at minimum again (heating potentiometer
turned to minimum)
♦ Repeat the adjustment procedure, if necessary;
♦ Seal the gas flow rate adjustment devices;
♦ Put the back of the control panel and the front cover back into position; turn the
selector to OFF to deactivate the “Chimney sweep” mode and then switch on the
boiler again
464544 4847 49 50
51
5354
52
Fig. 15