W415-1117 / A / 03.11.14
40
IOM
IOM
H18.6.1
The natural gas supply pressure should be a maximum of 7” w.c. and minimum of 5” w.c. The burner manifold
pressure is factory set to 3.5” w.c. The input rating of the furnace is based on 1000 Btu/ft.³ gas with a speci
fi
c
gravity of 0.6.
Since heating values for the gas vary geographically, the actual furnace input and output will vary accordingly.
For example, natural gas with a 900 Btu/ft.³ heating value will reduce the input to 90% of the rated input.
Natural gas with a 1100 Btu/ft.³ heating value will increase the input to approximately 110% of the rated input.
This is not usually a problem; however, adjustments to compensate for this can be made by minor adjustments
to the burner manifold pressure or by changing the burner ori
fi
ce size. Contact the fuel supplier for speci
fi
c
heating content values.
Any adjustments to the burner manifold pressure should be carried out with the use of a manometer or
calibrated Magnehelic® gauge. Do not adjust the gas valve pressure regulator more than ±0.3” w.c. Refer to
Setting The Manifold Gas Pressure and Figure 30.
IMPORTANT:
NEVER ADJUST THE INPUT
OF THE FURNACE TO
EXCEED THE INPUT SHOWN
ON THE RATING PLATE.
Input =
Heating Value of Gas x 3600
Time in Sec. for 1 cu. ft.
where:
•
input is expressed in Btu/hr
•
heating value of the gas is expressed in Btu/ft
3
• and time is the number of seconds required for
the test dial to indicate 1 cubic foot.
If using a gas meter with SI (metric) units:
•
1 cubic foot = 0.0283 cubic meters
•
1 cubic meter = 35.315 cubic feet
•
0.01 cubic meter = 0.3531 cubic feet
•
0.5 cubic meter = 1.766 cubic feet
13.6 CHECKING FURNACE INPUT
FIGURE 30 - MANOMETER MEASURING GAS MANIFOLD PRESSURE
H18.5.1
7. Turn on the gas supply and electrical power to the furnace.
8. Turn on system power and energize valve.
9. Using a leak detection solution, check for leaks at pressure boss screw. Bubbles forming indicate a leak.
SHUT OFF GAS AND FIX ALL LEAKS IMMEDIATELY!
H3.21
ALL REGULATOR ADJUSTMENTS MUST BE DONE BY A TRAINED, QUALIFIED
TECHNICIAN. IMPROPER MODIFICATIONS OR ADJUSTMENTS CAN RESULT IN FIRE OR
EXPLOSION CAUSING PROPERTY DAMAGE, SEVERE PERSONAL INJURY OR LOSS OF
LIFE.
WARNING
!
!
