baltur BGN 40 LX-V, Instruction Manual

Page: 40 / 133

40
EN
11) Set the burner to minimum flame (modulation servomotor set to minimum), check the quantity and appearance of
the flame making the necessary adjustments: see instructions elating to the gas valve model MB-VEF..,
DMV-VEF.. Afterwards, check the supplied gas quantity by reading the meter. If necessary, adjust the gas output
and the relevant combustion air by operating as described above. Then, check the combustion with the special
instruments (see chapter “Combustion control
”.
12) After adjusting the “minimum”, set the modulation switches to MAN (manual) and MAX (maximum) position. The
air regulation servomotor sets to “maximum” and as a consequence, also the gas supply reaches the “maximum”.
The quantity of supplied gas is then checked by reading the meter. With burner ignited at the maximum existing
output, measure the gas flow rate by calculating the difference between two reads performed after one minute from
one another. By multiplying the measured value by sixty, a sixty-minute flow rate – that is, one hour – is obtained.
By multiplying the hourly output (m
3 /h) by the gas heat value, you obtain the delivered power in Kcal/h, which must
correspond or be very close to that required by the burner (lower heat value for methane = 8550 Kcal/h). Avoid
operating the burner if the flow rate is more than the admissible for the boiler so as to prevent possible
damages to the same. Shut down the burner after the two meter reads.
13) To change the maximum gas output, operate on the air flow rate regulator since the gas flow rate automatically
adjust to the air supply. Then, operate on the cam regulating the air damper maximum aperture position (see dr. n°
0002933220 - 0002933490). Reduce the aperture angle of the air damper to reduce the gas flow rate, and vice
versa. To change the gas/air ratio, see instruction of gas valve MB-VEF.., DMV-VEF..
14) Afterwards, check the combustion with the special instruments and if necessary, check the existing regulation (air
and optionally gas). Check with the special instruments that the carbon oxide (CO) percentage in the flue
gas does not exceed the maximum admissible value of 0.1% and that CO
2
does not exceed 10% for meth-
ane. (See chapter “Combustion control”)
15) After adjusting the operation to the high flame (maximum) you must operate so that the air regulation servomo-
tor sets to the minimum to perform the control also in this position.
16) To set the air – and thus gas – regulation servomotor to the minimum, set the modulation switch to MIN.
17) When the air servomotor is set to minimum, and it is necessary to change the combustion conditions (gas/air), see
the instructions for regulating gas valves model MB-VEF .., DMV-VEF..
18) It is advisable to perform the combustion control using the instruments and, if necessary, change the previous
regulation also in some intermediate points of the modulation stroke.
19) Now, check the correct automatic modulation operation.
20) The air pressure switch has the function of locking the control box if the air pressure is not correct. The pressure
switch must thus be set to start by closing the contact (a normally open contact) when air pressure in the burner reach
a sufficient value. Note that if the normally open contact does not close (insufficient air pressure), the control box
performs its cycle but the ignition transformer does not start, the gas valves do not open and as a consequence, the
burner stops in lock. To check the correct operation of the air pressure switch, set the burner to the minimum
output, increase the regulation value so as to check when it should start to immediately “lock” the burner. Unlock the
burner by pressing the special push button and restore the pressure switch regulation to a sufficient value to detect
the existing air pressure during the pre-ventilation step. The pressure switch connection circuit provides for the
automatic control; thus, the contact provided to be closed when at rest (fan off, and thus, absence of air pressure in
the burner) must implement this condition, or the control box does not start (the burner remains off).
21) The gas pressure control switches (minimum and maximum), if installed, have the function of prev e nting the
burner from operating when gas pressure does not range in the expected values. From the specific function of the
pressure switches, it is evident that the minimum pressure control switch must used the contact that is closed when
it detects a higher pressure than that to which it is set, the maximum pressure control switch must use the contact
that is closed when it detects a lower pressure than that to which it is set. Therefore, the gas maximum and
minimum pressure switch regulation must be performed during the burner general test and inspection, based on
the pressure measured each time. Pressure switches are electrically connected in series; thus, the start (intended
as circuit opening) of any one of the gas pressure switches does not allow starting the control box and thus, the
burner. When the burner is operating (flame on), the start of the gas pressure switches (circuit opening) causes the
immediate shut down of the burner. Upon the general test and inspection of the burner, it is necessary to check the
correct operation of the pressure switches. By suitably acting on the respective regulation members, make sure
that the pressure switch starts (circuit opening), thus shutting down the burner.