46
READING GAS (METHANE) METER
When the burner is operating at maximum output, check that the quantity of gas delivered is necessary for the boiler’s
needs. The low calorific value for methane gas is about 8550 kcal/m
3
.
To find out the low calorific values of other types of gas, contact the Gas Distributing Company. Delivery per hour
should be taken at the meter. When checking delivery make sure that gas is not being consumed by other users.
If the gas delivery pressure at the meter is not above 400 mm.w.c., take into consideration the value indicated by the
meter without correcting it. For a first indication, turn on the burner and when it arrives at nominal delivery, measure
the gas output in one minute exactly (the difference between the two readings should be one minute exactly from one
to the other. Multiply this value by 60 in order to obtain the output for 60 minutes (one hour).
The output measured is considered the actual value if the meter reads a pressure below 400 mm.w.c. If the pressure
is more than 400 mm.w.c., the value read must be multiplied by a correction coefficient, as previously described.
Subsequently, multiply the delivery per hour (m
3
/h) by the gas calorific value to obtain the potentiality delivered in Kcal/
h; this should correspond or be very near to that requested for the boiler (low calorific value for methane gas = 8550
kcal/m
3
). Do not allow the burner to operate for a long time (only a few minutes) if the output exceeds the maximum
allowed for the boiler, to avoid possible damage to it; it would be timely to stop the burner immediately after having
taken the two meter readings.
Correcting the value indicated by the meter. If the meter measures the gas delivery at a pressure above 400
mm.w.c., it is necessary to multiply the value by a correction coefficient. As an indication, the correction coefficient
values to be adopted in function with the gas pressure existing at the meter, can be determined in the following way:
Add to number 1 (one) the number which expresses the gas pressure value in bar, existing at the meter.
Example n°1
Gas pressure at the meter = 2 bar, the multiplication coefficient is 1 + 2 = 3.
Therefore, if the meter reads a delivery of 100 m
3
/h, multiply it by 3 to obtain the actual output which is
100 m
3
/h x 3 = 300 m
3
/h.
Example n°2
Gas pressure at the meter = 1,2 bar, the multiplication coefficient is 1 + 1,2 = 2,2.
Therefore, if the meter reads a delivery of 100 m
3
/h, multiply it by 2,2 to obtain the actual output which is
100 m
3
/h x 2,2 = 220 m
3
/h.
Example n° 3
Gas pressure at the meter = 0,3 bar, (3000 mm.w.c.), the multiplication coefficient is 1 + 0,3 = 1,3.
Therefore, if the meter reads a delivery of 100 m
3
/h, multiply it by 1,3 to obtain the actual output which is 130 m
3
/h.
Example n°4
Gas pressure at the meter = 0,3 bar, (600 mm.w.c.), the multiplication coefficient is 1 + 0,06 = 1,06.
Therefore, if the meter reads a delivery of 100 m
3
/h, multiply it by 1,06 to obtain the actual output which is
100 m
3
/h x 1,06 = 106 m
3
/h.
MAINTENANCE
The burner does not need particular maintenance, it will be otherwise better to check periodically that the gas filter is
clean and the ionisation electrode efficient. The cleaning of the combustion head may result necessary.
For this reason it’s necessary to disassemble the head’s components.
The reassemble operation must be done carefully so as to avoid the electrode’s earthing or in short circuit with
following burner’s lock. It must be verified that the ignition electrode’s sparkle happens only between the same and
the drilled plate disc. To verify the ionisation stream, connect a micro-ammeter with adequate scale “in sequence” to
the ionisation circuit. The high insulation cable coming out from the electrode must be connected in negative ( -
indication) of the micro-ammeter.
The minimum value of secure the control box working is reported on the specific electric diagram.
USE OF THE BURNER
The burner operates fully automatically, therefore it is non necessary to carry out any kind at adjustment during its
operation. The “block” position is a safety position reached by the burner automatically when some of the components
of the burners or the plant do not work properly. It is necessary to check then whether the cause to the problem is a
dangerous one before unblocking the burner. The causes to the block may be temporary, for example when air in inside
the pipes. When it is unblocked, the burner starts operating properly. If the burner stops three or four times at a stretch,
it is necessary either to look for the cause to the problem and solve it or ask for the intervention of the after sales service.
The burner can remain in the “block” position without any limit in time. In emergency cases it is advisable and to close
the fuel valve, to disconnect the burner electrically.