18
NATURALGAS
(Dia)
PROPANE (LP)
(Dia)
45,000
2
23,000
#43
#55
70,000
3
23,000
#43
#55
92,000
4
23,000
#43
#55
115,000
5
23,000
#43
#55
140,000
6
23,000
#43
#55
GAS ORIFICES
MAXIMUM
INPUT
(BTUH)
NUMBER
OF
BURNERS
MAXIMUM
BTUH/BURNER
Heat Exchanger and Burner Orifice Specifications
NOTE:
Gas appliances located more than 2000 feet above
sea level must be derated 4% per 1000 feet of total ele-
vation and that variance in gas heating value and specific
gravity require change in manifold pressure to obtain rating,
it is mandatory that the input be adjusted at the installation
site. All installations should be made as outlined in the lat-
est edition of the National Fuel Gas Code ANSI Z223.1,sec-
tion “Procedures To Be Followed To Place An Appliance in
Operation”. Refer also to the “User’s Information Manual”
supplied with the unit for additional information on the gas
furnace.
Gas Supply And Manifold Check
Gas supply pressure and manifold pressure with the burners
operating must be as specified on the rating plate.
Gas Inlet Pressure Check
Gas inlet pressure must be checked and adjusted in accor-
dance to the type of fuel being consumed.
With Power And Gas Off:
1. Connect a water manometer or adequate gauge to the
inlet pressure tap of the gas valve.
Inlet gas pressure can also be measured by removing the
cap from the dripleg and installing a predrilled cap with a
hose fitting.
With Power And Gas On:
2. Put unit into heating cycle and turn on all other gas con-
suming appliances.
NATURAL
Min. 5.0" W.C., Max. 10.0" W.C.
PROPANE
Min. 11.0" W.C., Max. 14.0" W.C.
INLET GAS PRESSURE
NOTE:
Inlet Gas Pressure Must Not Exceed the Maximum
Value Shown.
If operating pressures differ from above, make necessary
pressure regulator adjustments, check piping size, etc., and/
or consult with local utility.
Manifold Pressure Check
The gas valve has a tapped opening to facilitate measure-
ment of the manifold pressure. A “U” Tube manometer hav-
ing a scale range from 0 to 12 inches of water should be
used for this measurement. The manifold pressure must be
measured with the burners operating.
1. With disconnect switch open, remove field connected
thermostat wire from terminal R, W1 and W2 on TB1.
Place jumper wire between R, W1 and W2 to engage
high stage heat. (note on 045 kbtu/hr units W2 is not
used, only jumper R to W1).
2. See Figure in input rating section for gas valve adjust-
ment.
To adjust the pressure regulator, remove the adjustment
screw or cover on the gas valve. Turn out (counterclock-
wise) to decrease pressure, turn in (clockwise) to increase
pressure. Only small variations in gas flow should be made
by means of the pressure regulator adjustment. In no case
should the final manifold pressure vary more than plus or
minus 0.3 inches water column from the specified nominal
pressure. Any major changes in flow should be made by
changing the size of the burner orifices. The measured in
-
put rate to the furnace must not exceed the rating specified
on the unit rating plate.
For natural gas, the high stage manifold pressure must be
between 3.2 and 3.8 inches water column (3.5 nominal).
Low stage manifold pressure must be between 1.7 to 2.3
inches water column (2.0 nominal).
3. To set low fire rate on 090, 115 and 140 kbtu/hr: Open
disconnect switch, and remove jumper from R to W2. To
set low fire manifold pressure, repeat steps above. Refer
to Figure in input rating section for location of high and
low stage adjustment.
For propane gas, the manifold pressure must be between
9.7 and 10.3 inches water column (10.0 nominal). Low stage
manifold must be between 5.7 and 6.3 inches water column
(6.0 nominal).
Gas Input (Natural Gas Only) Check
It is the responsibility of the contractor to adjust the gas input
to the unit.
To measure the gas input use a gas meter and proceed as
follows:
1. Turn off gas supply to all other appliances except the unit.
2. With the unit operating, time the smallest dial on the me-
ter for one complete revolution. If this is a 2 cubic foot dial,
divide the seconds by 2; if it is a 1 cubic foot dial, use the
seconds as is. This gives the seconds per cubic foot of
gas being delivered to the unit.
3. INPUT=GAS HTG VALUE x 3600 / SEC. PER CUBIC
FOOT
Example:
Natural gas with a heating value of 1000 BTU per
cubic foot and 34 seconds per cubic foot as determined by
Step 2, then:
Input = 1000 x 3600 / 34 = 106,000 BTU per Hour. NOTE:
BTU content of the gas should be obtained from the gas
supplier. This measured input must not be greater than
shown on the unit rating plate.
Adjust input rate by varying the adjustment of the gas pres-
sure regulator on the gas valve. All adjustments must be
made with furnace operating at high fire and at normal oper
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