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UNIT DAMAGE HAZARD
Failure to follow this caution may result in component
damage due to flame impingement of burners and heat
exchangers.
DO NOT redrill orifices. Improper drilling (burrs, out-of-
round holes, etc.) can cause excessive burner noise and
misdirection of burner flames. (See Fig. 56.)
e. Replace gas valve regulator adjustment screw seal cap.
f. Replace burner enclosure front and verify adjusted gas
input rate using method outlined in item 3.
g. Look through sight glass in burner enclosure and check
burner flame. Burner flame should be clear blue, almost
transparent. (See Fig. 57.)
h. Remove jumper from R and W.
3. Verify natural gas input rate by clocking gas meter.
NOTE:
Be sure all pressure tubing, combustion-air and vent
pipes, and burner box cover front are in place when checking input
by clocking gas meter.
a. Calculate high-altitude adjustment (if required).
UNITED STATES
At altitudes above 2000 ft, this furnace has been approved
for a 2 percent derate for each 1000 ft above sea level. See
Table 15 for derate multiplier factor.
CANADA
At installation altitudes between 2001 to 4500 ft, this
furnace must be derated 5 percent by an authorized Gas
Conversion Station or Dealer. To determine correct input
rate for altitude, see example above and use 0.95 as derate
multiplier factor.
b. Reinstall burner box cover.
c. Gas valve regulator seal cap MUST be on.
d. Turn off all other gas applications and pilots.
e. Start furnace and let operate for 3 minutes.
f. Measure time (in sec) for gas meter to dial to complete 1
revolution.
g. Refer to Table 16 for cu ft of gas per hr.
h. Multiply gas rate (cu ft/hr) X heating value (Btu/cu ft)
using
natural
gas
heating
value
from
local
gas
utility/supplier.
Fig. 55—Redundant Automatic Gas Control Valve
A95622
MANIFOLD
PRESSURE TAP
GAS
PRESSURE
REGULATOR
ADJUSTMENT
BURNER
ENCLOSURE
REFERENCE
PRESSURE
TAP
INLET
PRESSURE TAP
ON AND
OFF SWITCH
Fig. 56—Orifice Holes
A93059
BURNER
ORIFICE
Fig. 57—Burner Flame
A89020
;;
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BURNER FLAME
BURNER
MANIFOLD
EXAMPLE:
100,000 Btuh input furnace installed at 4300 ft.
Derate
Furnace Input Rate
Furnace Input Rate
X
Multiplier
=
at Installation
at Sea Level
Factor
Altitude
100,000
X
0.91
=
91,000
54
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