Installation guide
1. With gas OFF, Connect U-Tube manometer to tapped open-
ing on gas valve. Use manometer with a 0 to min. 12" water
column range.
2. Turn gas ON and remove adjustment screw cover on gas
valve. Turn counterclockwise to decrease pressure and
clockwise to increase.
NOTE: Adjustment screw cover MUST be placed on gas valve
before reading manifold pressure and operating furnace.
Main Burner
Burner Face
10-10-78
3. For altitudes up to 2000', set pressure to value shown in
Table 2. For altitudes up to 2000' to 8000', see Section
6. "Gas Supply and Piping" for correct pressure value.
Adjust Pilot Burner
The furnace has a pilot flame to light the main burner. The flame
should surround 3/8" to 1/2" of the flame rod. See Figure 16. To
adjust, remove cap from pilot adjusting screw on gas valve. Turn
screw counterclockwise to increase or clockwise to decrease
flame as required. Replace cap after adjusting screw.
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Pilot Burner
3/8to 1/2"
Proper flame
adjustment
Igniter-sensor
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j 10-12-12c
Temperature Rise Check
The blower speed MUST be set to give the correct air temperature
rise through the furnace as marked on the rating plate. Tempera-
ture rise is the difference between supply and return air tempera-
tures.
To check temperature rise,use the following procedure:
1. Place thermometers in supply and return air registers as
close to furnace as possible, avoiding direct radiant heat
from heat exchangers.
2. Operate furnace on high fire for 10 minutes with all the reg-
isters and duct dampers open by using a jumper wire on R
to Wl and W/W2 thermostat connections on the fan board.
3. Take readings and compare with range specified on rating
plate.
4. If the temperature rise is not in the correct range, the blower
speed must be changed. A higher blower speed will lower
the temperature rise. A lower blower speed will increase
the temperature rise.
5. Repeatsteps2thru4with the furnace operating on lowfire
for 10 minutes by using a jumper wire on the R to W/W2
thermostat connections on the fan board.
6. Remove the jumper wire after the adjustments are com-
plete.
Changing Blower Speed
Main Burner Flame Check
Allow the furnace to run approximately 10 minutes then inspect
the main burner and pilot flames. See Figure 17.
Check for the following (Figure 17):
• Stable and blue flames. Dust may cause orange tips or
wisps of yellow, but flames MUST NOT have solid, yel-
low 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.
Electrical shock hazard.
Turn OFF power to furnace before changing speed
taps.
Failure to do so can result in personal injury and/or
death.
NOTE: The speed taps that the manufacture sets from the factory
for this product are based on a nominal 400 CFM per ton cooling
and the basic mid range on the temperature rise for heating.
Since the manufacturer cannot establish the static pressure
that will be applied to the unit, it is the responsibility of the
installer dealer/contractor to select the proper speed taps for
the application when the unit is installed.
If it is necessary to change speeds, refer to steps below.
1. Refer to Furnace Wiring Diagram for location of the heating
and cooling speed taps located on the electronic fan control
as well as location of unused blower motor speed leads. Use
the chart (Table 5) to determine the blower motor speed set-
tings.