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Table 21 (Continued) - - Orifice Size and Manifold Pressure (in. w.c.) for Gas Input Rate
(TABULATED DATA BASED ON 13,000 BTUH PER BURNER, DERATED 2%/1000 FT (305M) ABOVE SEA LEVEL
7001
(2134)
8000
(2438)
8001
(2439)
9000
(2743)
9001
(2744)
10000
(3048)
* Orifice numbers shown in BOLD are factory-installed.
Check Inlet Gas Pressure
The inlet gas pressure must be checked with the furnace operating
in maximum heat. This is necessary to make sure the inlet gas
pressure does not fall below the minimum pressure of 4.5 in. w.c.
1. Make sure the gas supply is turned off to the furnace and at
the electric switch on the gas valve.
2. Loosen set screw on inlet tower pressure tap no more than
one full turn with a 3/32- -in. hex wrench or remove the
1/8- -in. NPT plug from the inlet pressure tap on the gas
valve.
3. Connect a manometer to the inlet pressure tap on gas valve.
4. Turn on furnace power supply.
5. Turn gas supply manual shutoff valve to ON position.
6. Turn furnace gas valve switch to ON position.
7. Jumper R and W thermostat connections at the furnace
control board.
8. When main burners ignite, confirm inlet gas pressure is
between 4.5 in. w.c. (1125 Pa) and 13.6 in. w.c. (3388 Pa).
9. Remove jumper across thermostat connections to terminate
call for heat. Wait until the blower off delay is completed.
10. Turn furnace gas valve electric switch to OFF position.
11. Turn gas supply manual shutoff valve to OFF position.
12. Turn off furnace power supply.
13. Remove manometer from the inlet pressure tap of the gas
valve.
WARNING
!
FIRE HAZARD
Failure to follow this warning could result in personal injury,
death, and/or property damage.
Inlet pressure tap set screw must be tightened and 1/8- -in. NPT
pipe plug must be installed to prevent gas leaks.
68
26,000 BTUH ONLY
ORIFICE SIZE* AND MANIFOLD PRESSURE (IN WC) FOR GAS INPUT RATE
650
43
675
44
700
44
725
44
to
750
44
775
44
800
44
825
44
625
43
650
44
675
44
700
44
to
725
44
750
44
775
44
43
600
625
44
650
44
to
675
44
700
44
725
44
Specifications subject to change without notice.
1.7
43
1.8
42
1.8
43
1.7
43
1.7
44
1.8
44
1.6
44
1.7
44
1.5
44
1.5
44
1.4
44
1.4
44
1.3
44
1.4
44
1.2
44
1.3
44
1.7
43
1.8
43
1.8
43
1.7
43
1.7
44
1.8
44
1.6
44
1.6
44
1.5
44
1.5
44
1.4
44
1.4
44
1.3
44
1.3
44
1.7
43
1.8
43
1.8
43
1.6
43
1.7
44
1.7
44
1.6
44
1.6
44
1.4
44
1.5
44
1.3
44
1.4
44
14. Tighten set screw on inlet tower pressure tap with 3/32- -in.
hex wrench, or if 1/8- -in. NPT plug was removed, apply
pipe dope sparingly to end of plug and re- -install in the gas
valve.
1/2" NPT
INLET
INLET PRESSURE
TAP SET SCREW:
3/32" HEX HEAD
ACCEPTS 5/16"
HOSE CONNECTION
Standard Capacity Gas Valve with Tower Pressure Ports
1/2" NPT
INLET
INLET PRESSURE
TAP SET SCREW:
3/32" HEX HEAD
ACCEPTS 5/16"
HOSE CONNECTION
PRESSURE TAP
Representative drawing only, some models may vary in appearance.
26,000 BTUH Low Capacity Gas Valve with Tower Pressure
1.5
42
1.6
1.7
43
1.8
1.8
43
1.7
1.7
44
1.8
1.6
44
1.6
1.5
44
1.5
1.4
44
1.4
1.3
44
1.4
1.8
42
1.6
1.7
43
1.8
1.8
43
1.6
1.7
44
1.7
1.6
44
1.6
1.5
44
1.5
1.4
44
1.4
1.8
42
1.6
1.7
43
1.7
1.8
44
1.8
1.7
44
1.7
1.5
44
1.6
1.4
44
1.5
MANIFOLD PRESSURE TAP
SET SCREW: 3/32" HEX HEAD
ACCEPTS 5/16" HOSE CONNECTION
OUTP
INP
ON/OFF SWITCH
1/8" NPT INLET
PRESSURE TAP
Representative drawing only, some models may vary in appearance.
MANIFOLD PRESSURE TAP
SET SCREW: 3/32" HEX HEAD
ACCEPTS 5/16" HOSE CONNECTION
OUTP
INP
REGULATOR SEAL CAP
1.5"
ON/OFF
1/8" NPT INLET
W.C
SWITCH
.
Ports
Fig. 59 - - Gas Valves
440 01 6101 00
A150572
1/2" NPT
OUTLET
REGULATOR SEAL CAP
(REGULATOR ADJ.
UNDER CAP)
A170140
1/2" NPT
OUTLET
(REGULATOR ADJ.
UNDER CAP)
A170118
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