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Table 11 - - Orifice Size and Manifold Pressure for Gas Input Rate (CONT.)
(Tabulated Data Based on 22,000 Btuh High- -Heat/14,500 Btuh for Low- -Heat per Burner, Derated 4 Percent for Each 1000 Ft..
AVG. GAS
ALTITUDE
HEAT VALUE
AT ALTITUDE
RANGE (FT.)
(BTUH/CU FT.)
725
750
775
USA
5001 to
800
825
Only
6000
850
875
900
AVG. GAS
ALTITUDE
HEAT VALUE
RANGE (FT.)
AT ALTITUDE
(BTUH/CU FT.)
675
700
725
USA
6001 to
750
775
Only
7000
800
825
850
AVG. GAS
ALTITUDE
HEAT VALUE
RANGE (FT.)
AT ALTITUDE
(BTUH/CU FT.)
650
675
700
USA
7001 to
725
750
Only
8000
775
800
825
AVG. GAS
ALTITUDE
HEAT VALUE
RANGE (FT.)
AT ALTITUDE
(BTUH/CU FT.)
625
650
675
USA
8001 to
700
Only
9000
725
750
775
600
625
USA
9001 to
650
Only
10,000
675
700
725
* Orifice numbers 43 are factory installed
Check Safety Controls
The flame sensor, gas valve, and pressure switch were all checked
in the Start- -up procedure section as part of normal operation.
1. Check Main Limit Switch
This control shuts off combustion system and energizes
air- -circulating blower motor, if furnace overheats. By
using this method to check limit control, it can be
established that limit is functioning properly and will
operate if there is a restricted return- -air supply or motor
failure. If limit control does not function during this test,
cause must be determined and corrected.
a. Run furnace for at least 5 minutes.
b. Gradually block off return air with a piece of
cardboard or sheet metal until the limit trips.
c. Unblock return air to permit normal circulation.
d. Burners will re- -light when furnace cools down.
Above Sea Level)
SPECIFIC GRAVITY OF NATURAL GAS
0.58
Orifice
Manifold
Orifice
No.
Pressure
No.
43
3.4/1.5
43
43
3.2/1.4
43
44
3.4/1.5
44
44
3.2/1.4
44
46
3.8/1.7
45
46
3.6/1.6
46
47
3.8/1.7
46
47
3.6/1.6
47
SPECIFIC GRAVITY OF NATURAL GAS
0.58
Orifice
Manifold
Orifice
No.
Pressure
No.
43
3.4/1.5
43
44
3.6/1.6
43
44
3.4/1.5
44
45
3.8/1.7
44
46
3.7/1.6
45
46
3.5/1.5
46
47
3.7/1.6
46
47
3.5/1.5
47
SPECIFIC GRAVITY OF NATURAL GAS
0.58
Orifice
Manifold
Orifice
No.
Pressure
No.
44
3.6/1.6
43
44
3.3/1.5
44
45
3.8/1.6
44
46
3.7/1.6
46
46
3.4/1.5
46
47
3.6/1.6
47
47
3.4/1.5
47
48
3.7/1.6
48
SPECIFIC GRAVITY OF NATURAL GAS
0.58
Orifice
Manifold
Orifice
No.
Pressure
No.
44
3.3/1.5
44
45
3.7/1.6
44
46
3.6/1.6
46
47
3.8/1.7
46
47
3.6/1.6
47
48
3.8/1.7
47
48
3.6/1.5
48
45
3.7/1.6
45
46
3.6/1.6
46
47
3.8/1.6
46
47
3.5/1.5
47
48
3.7/1.6
48
48
3.5/1.5
48
0.60
0.62
Manifold
Orifice
Manifold
Pressure
No.
Pressure
3.5/1.5
43
3.6/1.6
3.3/1.4
43
3.4/1.5
3.5/1.5
43
3.2/1.4
3.3/1.4
44
3.4/1.5
3.8/1.6
44
3.2/1.4
3.7/1.6
46
3.8/1.7
3.5/1.5
46
3.6/1.6
3.8/1.6
46
3.4/1.5
0.60
0.62
Manifold
Orifice
Manifold
Pressure
No.
Pressure
3.5/1.5
43
3.6/1.6
3.3/1.4
43
3.4/1.5
3.5/1.5
44
3.6/1.6
3.3/1.4
44
3.4/1.5
3.7/1.6
45
3.8/1.7
3.6/1.6
46
3.8/1.6
3.4/1.5
46
3.5/1.5
3.6/1.6
47
3.8/1.6
0.60
0.62
Manifold
Orifice
Manifold
Pressure
No.
Pressure
3.2/1.4
43
3.4/1.5
3.5/1.5
44
3.6/1.6
3.2/1.4
44
3.3/1.4
3.8/1.7
45
3.7/1.6
3.6/1.5
46
3.7/1.6
3.8/1.6
46
3.4/1.5
3.5/1.5
47
3.7/1.6
3.8/1.6
47
3.4/1.5
0.60
0.62
Manifold
Orifice
Manifold
Pressure
No.
Pressure
3.5/1.5
44
3.6/1.6
3.2/1.4
44
3.3/1.4
3.8/1.6
45
3.7/1.6
3.5/1.5
46
3.6/1.6
3.7/1.6
47
3.8/1.7
3.5/1.5
47
3.6/1.6
3.7/1.6
48
3.8/1.7
3.8/1.7
44
3.3/1.4
3.7/1.6
46
3.8/1.7
3.4/1.5
46
3.6/1.5
3.6/1.6
47
3.7/1.6
3.8/1.7
47
3.5/1.5
3.6/1.6
48
3.7/1.6
2. Check draft safeguard switch. The purpose of this control
is to cause the safe shutdown of the furnace during certain
blocked vent conditions.
a. Verify vent pipe is cool to the touch.
b. Disconnect power to furnace and remove vent
connector from furnace vent elbow.
c. Restore power to furnace and set room thermostat
above room temperature.
d. After normal start- -up, allow furnace to operate for 2
minutes, then block vent elbow in furnace 80 percent
of vent area with a piece of flat sheet metal.
e. Furnace should cycle off within 2 minutes. If gas does
not shut off within 2 minutes, determine reason draft
safeguard switch did not function properly and correct
condition.
f. Remove blockage from furnace vent elbow.
g. Switch will auto- -reset when it cools.
h. Re- -install vent connector.
47
0.64
Orifice
Manifold
No.
Pressure
43
3.7/1.6
43
3.5/1.5
43
3.3/1.4
44
3.5/1.5
44
3.3/1.4
45
3.8/1.6
46
3.7/1.6
46
3.5/1.5
0.64
Orifice
Manifold
No.
Pressure
43
3.7/1.6
43
3.5/1.5
43
3.2/1.4
44
3.5/1.5
44
3.2/1.4
45
3.7/1.6
46
3.6/1.6
46
3.4/1.5
0.64
Orifice
Manifold
No.
Pressure
43
3.5/1.5
43
3.2/1.4
44
3.4/1.5
44
3.2/1.4
46
3.8/1.6
46
3.6/1.5
47
3.8/1.6
47
3.6/1.5
0.64
Orifice
Manifold
No.
Pressure
43
3.2/1.4
44
3.4/1.5
45
3.8/1.7
46
3.7/1.6
46
3.5/1.5
47
3.7/1.6
47
3.5/1.5
44
3.4/1.5
45
3.8/1.6
46
3.7/1.6
46
3.4/1.5
47
3.6/1.6
48
3.8/1.7
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