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Adjust the Furnace Input Rate
(if required)
For altitudes 4,500 to 7,500 feet above sea level.
1. Remove the burner access door.
2. Move the gas control switch to the OFF position. Use only
your hand to move the gas control switch; tools are not
required.
3. Remove the outlet pressure tap plug on the gas control valve
and connect pressure gauge to the ¹⁄₈ in. NPT outlet
pressure tap.
Gas Control Valve
2
1
1/2" NPT Inlet
¹⁄₈
1.
" NPT Inlet pressure tap
2. Regulator adjusting cap
3. Diagnostic LED
¹⁄₈
4.
" NPT Outlet pressure tap
5. Gas control switch
4. Be sure the gas control switch has been in the OFF position
for at least 5 minutes before starting the unit.
5. Move the gas control switch to the ON position.
NOTE: This furnace is equipped with an ignition device which
automatically lights the burner. This furnace cannot be lighted
manually. Do not try to light the burner by hand.
6. Turn on the electrical power to the furnace.
7. Set the room thermostat to a point above room temperature
to light the main burners.
8. Observe the pressure reading on the pressure gauge.
18
9. Refer to the Manifold Pressure vs. Altitude chart for the
correct manifold pressure. If necessary, remove the regulator
adjusting cap on the gas valve and turn the regulator
adjusting screw clockwise to increase pressure and input, or
counterclockwise to decrease pressure and input.
IMPORTANT: If the manifold pressure cannot be adjusted to
the correct value, contact your gas supplier.
10. Move the gas control switch to the OFF position.
11. Disconnect the pressure gauge from the ¹⁄₈ in. NPT outlet
pressure tap.
12. Replace outlet pressure tap plug and the regulator adjusting
cap on the gas valve.
13. Move the gas control switch to the ON position.
14. Replace the burner access door.
3
15. Set the room thermostat to the desired temperature
necessary to achieve optimum temperature rise.
Manifold Pressure vs. Altitude Chart
4
1/2" NPT Outlet
Altitude (ft)
5
For Altitudes 7,500 to 10,000 feet above sea level.
Do not adjust manifold pressure. An orifice change is required.
For the correct orifice size, see Table F.4 in Appendix F of the
National Fuel Gas Code (ANSI Z223.1/NFPA 54, latest edition).
Natural Gas
Heating Value
(BTU/ft
3
)
2000
948
3000
914
4000
881
4500
865
5000
849
5500
833
6000
818
6500
802
7000
787
7500
771
Manifold
Input
Pressure
Factor
(in. W.C.)
3.50
0.9666
3.50
0.9499
3.50
0.9332
3.50
0.9249
3.29
0.8900
3.27
0.8790
3.25
0.8680
3.23
0.8570
3.21
0.8460
3.19
0.8350
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