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SettingtheSubbase
Furnoc / ' _
FloorBase
Floor
Wood Scre_ _/'_ _ Plenum 25-20-46a
This subbase for combustible floors has been designed so that the
height of the subbase raises the downflow coil off the floor to allow
easy installation of the condensate drain. See Figure 50.
Condensate Line Raised by Base
25-20-52
9. Checks and Adjustments
NOTE: Verify the input rate of the furnace.
FIRE OR EXPLOSION HAZARD.
Failure to turn OFF gas at shut off before
connecting manometer could result in death,
personal injury and/or property damage.
Turn OFF gas at shut off before connecting
manometer.
Startup
NOTE: Refer to the start-up procedures in the "User's Information
Manual' or to the "Operating Instructions Label' on the furnace.
5. Remove manifold pressure adjustment screw cover on fur-
nace gas control valve. Turn adjusting screw counterclock-
wise to decrease manifold pressure and clockwise to
increase pressure.
NOTE: Adjustment screw cover MUST be replaced on gas control
valve before reading manifold pressure and operating furnace.
6. Set manifold pressure to value as shown in Table 8,
Table 9, Table 10 or Table 11.
7. When the manifold pressure is properly set, replace the ad-
justment screw cover on the gas control valve.
8. Remove jumper wire from thermostat connection on the
control board. Remove manometer connection from man-
ifold pressure tap, and replace plug in gas valve.
9. Check for leaks at plug.
10. Replace the burner compartment door.
Main Burner Flame Check
FIRE OR EXPLOSION HAZARD.
Failure to correct hazard could result in death,
personal injury and/or property damage.
If any sparks, odors or unusual noises occur,
immediately shut OFF power to furnace. Check for
wiring errors or obstruction to blower.
Gas Supply Pressure
Gas supply pressure should be within minimum and maximum val-
ues listed on rating plate. Pressures are usually set by gas suppli-
ers.
Manifold Gas Pressure Adjustment
NOTE: Make adjustment to manifold pressure with burners oper-
ating.
1.
2.
Remove the burner compartment door.
Remove the blower compartment door. A jumper wire
needs to be placed on furnace control R to W. Then replace
blower compartment door.
3. With gas OFF, connect manometer to tapped opening on
gas valve. Use manometer with a 0 to 15" water column
range.
4. Turn gas ON and remove adjustment screw cover on gas
valve. Turn counterclockwise to decrease pressure and
clockwise to increase.
AIIowthe furnace to run approximately 10 minutes then inspect the
main burner. See Figure 51.
Check for the following (Figure 51):
• Stable and blue flames. Dust may cause orange tips or
wisps of yellow, but flames MUST NOT have solid, yellow
tips.
• Flames extending directly from burner into heat ex-
changer.
• Flames do NOT touch sides of heat exchanger.
If any problems with main burner flames are noted, it may be nec-
essary to adjust gas pressures, or check for drafts.
_ ;;;;;;;; ;;;;;;;;;;;;;;;;;;2;;¸;¸¸¸122
Main Burner
10-10-78
NOTE: For Ignitor location see F_.N.ure 52.
44001 102102
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