30
441 01 2611 06
2. Turn gas ON. Operate the furnace by using a jumper wire on
the R to W thermostat connections on the fan board.
3. Remove manifold pressure adjustment screw cover on fur-
nace gas control v alve. Turn adjusting screw counterclock-
wise to decrease manifold pressure and clockwise to
increase pressure.
NOTE:AdjustmentscrewcoverMUSTbe replacedongascontrol
valve before reading manifold pressure and operating furnace.
4. Set manifold pressure to value shown in Table 7 or Table 8.
5. When the manifold pressure is properly set, replace the ad-
justment screw cover on the gas control valve.
6. Remove jumper wire from thermostat connection on fan
board. Remove manometer connection from manifold pres-
sure tap, and replace plug in manifold.
7. Check for leaks at plug.
Adjust Pilot Burner
The furnace has a pilot flame to light the main burner. The flame
shouldsurround
3
/
8
² to
1
/
2
² oftheflamerod.SeeFigure 35.To ad-
just, remove cap from pilot adjusting screw on gas control valve.
Turnscrewcounterclockwisetoincreaseorclockwisetodecrease
flame as required. Replace cap after adjusting screw.
Pilot Burner
Figure 35
Proper Flame
Adjustment
Flame Rod
Hot Surface
Igniter
10 -- 11 -- 6 5
Natural Gas Input Rating Check
The gas meter can be used to measure input to furnace.
Check with gas supplier for actual BTU content.
1. TurnOFFgassupplytoallappliancesotherthanfurnaceand
start furnace. Use jumper wire on R to W.
2. Timehowmany seconds it takes thesmallest dial on the gas
meter to make one complete revolution.
Note: Ifmeterusesa2cubicfootdial, divide results (seconds)by
two.
Refer to Example. The Example is based on a natural gas BTU
content of 1,000 BTU’s per cubic foot.
Example
Natural Gas
BTU Content
No. of Seconds
Per Hour
Time Per Cubic
Foot in
Seconds
BTU Per
Hour
1,000 3,600 48 75,000
1,000 x 3,600 ¸ 48 = 75,000 BTUH
3. Remove jumper wire from R to W1.
4. Relight all appliances and ensure all pilots are operating.
Orifice Sizing
NOTE: Factory sized orifices for natural and LP gas are listed in
the furnace Technical Support Manual.
Ensure furnace is equipped with the correctmain burner orifices.
Refer to Table 7 or Table 8 for correct orifice size and manifold
pressure for a given heating value and specific gravity fornatural
and propane gas.
Operation Above 2000¢ Altitude
FIRE, EXPLOSION, CARBON MONOXIDE
POISONING HAZARD.
Failure to follow these instructions exactly could
resultindeath,personalinjuryand/orpropertydam-
age.
This high--altitude gas--conversion shall be done by
a qualified service agency in accordance with the
Manufacturer’s instructions and all applicable
codes and requirements, or in the absence of local
codes, the applicable national codes.
!
W
RNING
Thesefurnacemaybeusedatfullinputratingwheninstalledatal-
titudesupto2000¢.Wheninstalledabove2000¢,theinputmustbe
decreased2%(natural)or4%(LP)foreach1000¢ abovesealevel.
This may be accomplished by a simple adjustment of manifold
pressure or an orifice change, or a combination of a pressure ad-
justmentandanorificechange.The c hanges required dependon
theinstallationaltitudeandtheheatingvalueofthefuel.Table 7 &
Table 8 showtheproperfurnacemanifoldpressureandgasorifice
sizetoachieveproperperformancebasedonelevationabovesea
level for both natural gas and propane gas.
To use the natural gas table, first consult your local gas utility for
theheatingv alueofthegassupply.Selecttheheatingvalue inthe
firstcolumnandfollowacrossthetableuntiltheappropriateeleva-
tionfortheinstallationisreached.Thevalueintheboxattheinter-
section of the altitude and heating value provides not only the
manifoldpressurebutalsotheorificesize.Inthenaturalgastables
thefactoy--s hippedorificesizeisinbold(42).Othersizes mustbe
obtained from service parts.
High Altitude Input Rate =
Nameplate Sea Level Input Rate x (Multiplier)
High Altitude Multiplier
Ele
ation
Natural Gas LP Gas
2001¢ - 3000¢ 0.95 0.90
3001¢ - 4000¢ 0.93 0.86
4001¢ - 5000¢ 0.91 0.82
5001¢ - 6000¢ 0.89 0.78
6001¢ - 7000¢ 0.87 0.74
7001¢ - 8000¢ 0.85 0.70
* Based on mid--range of elevation.
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