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8.
COMBUSTION ARRANGEMENT REQUIREMENTS
8.1
The NPM burner has been designed to fire with high combustion efficiency into combustion chambers with
positive, balanced or negative pressures using natural or PROPANE gas only.
8.2
In order to fire efficiently, the burner requires an adequate supply of combustion air. Ventilation to any
enclosed area should be provided on the basis of 1/2 square inch of opening for each 1,000 BTU/HR
input. This excludes the requirement for any other fired equipment in the area. Consult NFPA 54 for
combustion air requirement. The enclosed area should not become excessively hot and under no
circumstances should be under a negative pressure.
The burner should be initially set up and serviced at regular intervals (preferably at the beginning of and
mid way through high use periods) by a trained serviceman using the proper test instruments. Failure to
maintain the correct burner settings may result in inefficient gas consumption, premature wear of burner
and heat exchanger components, uncontrolled combustion.
8.3
Approximate gas flow rates and corresponding pressures are shown in Table 4 for natural gas and
propane gas. These rates/pressures represent approximately 5% excess 0
pressure. Since the amount of excess air will affect the actual manifold pressure/rate, verification of the
exact firing rate should be confirmed by clocking the gas meter and applying the appropriate correction
factor.
8.4
The necessary test instrumentation are:
a. O
analyzer (electronic or Fyrite absorption system)
2
b. CO indicator (Monoxor or similar)
c. Stack thermometer
d. Draft gauge or inclined manometer
e. U-tube manometer or calibrated 0-10" and 0-35" W.C. pressure gauge
f.
Combination volt/ammeter
g. D.C. Micro-Ammeter
Table 4. Manifold Pressure Chart. The pressures shown represent a zero furnace pressure. Actual
furnace pressure must be added to these pressures to obtain the total pressure needed at a given firing
rate.
10
8
6
4
2
0
0
Manifold Pressure vs. Firing Rate
NPM15
500
1000
Firing Rate (MBH)
NPM30(A)
1500
2000
9
at 0.0" W.C. furnace
2
NPM50
2500
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