18
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.
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. Set the room thermostat to the desired temperature
necessary to achieve optimum temperature rise.
Manifold Pressure vs. Altitude
Chart
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).
Complete Installation
IMPORTANT: Do not use this furnace if any part has been under
water. Immediately call a qualified person to inspect the furnace
and to replace any part of the control system and gas control
which has been under water.
1. Check to be sure you have all of your tools.
2. Dispose of all packaging materials.
3. Check the furnace in its final location. Be sure the vent is not
blocked.
Measure Temperature Rise
1. After 20 minutes of heating operation, measure the furnace
temperature rise. Take air temperature readings in both the
return air ducts and the heated air ducts (about 6 ft from the
furnace where they will not be affected by radiant heat) as
shown.
NOTE: If more than one run of return or heated air ducts is
used, air temperature measurements should be taken in each
duct. These measurements can be converted to an average
to obtain the temperature rise of the whole system.
2. If furnace doesn't maintain temperature rise within the range
shown on the furnace rating plate, adjust the blower speed.
Natural Gas
Altitude (ft)
Heating Value
(BTU/ft
3
)
Manifold
Pressure (in.
W.C.)
Input
Factor
2000
948
3.50
0.9666
3000
914
3.50
0.9499
4000
881
3.50
0.9332
4500
865
3.50
0.9249
5000
849
3.29
0.8900
5500
833
3.27
0.8790
6000
818
3.25
0.8680
6500
802
3.23
0.8570
7000
787
3.21
0.8460
7500
771
3.19
0.8350
1. Measure return air here.
2. Measure supply temperature here.
Warm Air
Return Air
1
2
