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1.
Turn OFF gas supply to all appliances and start furnace.
Use jumper wire on R to W for Heat.
2.
Time how many seconds it takes the smallest dial on the gas
meter to make one complete revolution. Refer to Example.
NOTE: If meter uses a 2 cubic foot dial, divide results
(seconds) by two.
Example
No. of
Natural Gas
Seconds
BTU Content
Per Hour
1,000
3,600
1,000 x 3,600 ÷ 48 = 75,000 BTUH
3.
Remove jumper wire from R to W.
4.
Relight all appliances and ensure all pilots are operating.
Main Burner Flame Check
Allow the furnace to run approximately 10 minutes then inspect the
main burner. See Figure 52.
Check for the following (Figure 52):
• 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
exchanger.
• Flames do NOT touch sides of heat exchanger
If any problems with main burner flames are noted, it may be
necessary to adjust gas pressures, or check for drafts.
Figure 52
Main Burner
NOTE: For Ignitor location see Figure 53.
Figure 53
Ignitor Location in(mm)
1/
(52.4)
2
16
5
/
(8)
16
NOTE: Flame sensor has a different orientation in all 050 models.
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.
Temperature rise is the difference between supply and return air
temperatures.
440 01 1024 01
Time Per
BTU Per
Cubic Foot in
Hour
Seconds
48
75,000
.
Burner Face
10--10--78
1
/
(6.4)
4
Specifications are subject to change without notice
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 continuously for 15 minutes with all
registers and duct dampers open.
3.
Take reading and compare with range specified on rating
plate.
4.
If the correct amount of temperature rise is NOT obtained, it
may be necessary to change blower speed. A higher blower
speed will lower the temperature rise. A lower blower speed
will increase the temperature rise.
Changing Blower Speed
WARNING
!
ELECTRICAL SHOCK HAZARD.
Failure to follow this warning could result in
personal injury or death.
Turn OFF power to furnace before changing
speed taps.
NOTE: The speed taps that the manufacturer 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.
CAUTION
!
REDUCED FURNACE LIFE HAZARD.
Failure to follow this caution may result in reduced
furnace life.
Use ONLY the blower motor speed taps insert
indicated in the Circulation Air Blower Data for
setting air temperature rise.
Table 14
Blower Speed Chart
Wire Color
Black
Orange*
Blue
Red
* Med--High speed may not be provided on all models.
1.
Refer to Furnace Wiring Diagram for location of the heating
and cooling speed taps located on the furnace control as
well as location of unused blower motor speed leads. Use
the chart (Table 14) to determine the blower motor speed
settings.
2.
Change the heat or cool blower motor speed by removing
the motor lead from the "Heat" or "Cool" terminal and
replace it with the desired motor speed lead from the
"Unused Motor Lead" location. Connect the wire
previously removed from the "Heat" or "Cool" terminal to the
vacated "Unused Motor Lead" terminal.
Motor Speed
High
Med--High
Medium
Low
43
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