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 12 for derate multiplier factor and example.
EXAMPLE: 100,000 BTUH HIGH-HEAT INPUT FURNACE
INSTALLED AT 4300 FT.
Furnace Input Rate
at Sea Level
X
Derate
Multiplier
Factor
=
Furnace Input Rate
at Installation
Altitude
100,000 X 0.91 = 91,000
CANADA
At installation altitudes from 2000 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 multi-
plier factor.
b. Reinstall burner box cover.
NOTE: Clocking gas input rate MUST always be performed with
the burner box cover INSTALLED.
c. Check that gas valve adjustment caps are in place for
proper input to be clocked.
d. Obtain average heat value (at altitude) from local gas
supplier.
NOTE: Be sure heating value of gas used for calculations is
correct for your altitude. Consult local gas utility for altitude
adjustment of gas heating value.
e. Check and verify orifice size in furnace. NEVER ASSUME
THE ORIFICE SIZE. ALWAYS CHECK AND VERIFY.
f. Turn off all other gas appliances and pilots.
g. Move setup switch SW1-2 to ON position. (See Fig. 32.)
This keeps furnace locked in low-heat operation.
h. Jumper R to W/W1.
i. Let furnace run for 3 minutes in low-heat operation.
j. Measure time (in sec) for gas meter to complete 1 revolu-
tion. Note reading.
k. Refer to Table 13 for cubic ft of gas per hr.
l. Multiply gas rate cu ft/hr by heating value (Btu/cu ft).
Fig. 62—Redundant Automatic Gas Valve
A97386
ON/OFF
SWITCH
INLET
PRESSURE
TAP
ON
O
F
F
BURNER
ENCLOSURE
REFERENCE
PRESSURE TAP
MANIFOLD
PRESSURE
TAP
LOW-FIRE
ADJUSTMENT
ALLEN SCREW
(UNDER CAP)
HIGH-FIRE
ADJUSTMENT
ALLEN SCREW
(UNDER CAP)
DO NOT redrill orifices. Improper drilling (burrs, out-of-
round holes, etc.) can cause excessive burner noise and
misdirection of burner flames. This will result in flame
impingement of burners and heat exchangers, causing fail-
ures. (See Fig. 63.)
A93059
Fig. 63—Burner Orifice
BURNER
ORIFICE
Fig. 64—Burner Flame
A89020
BURNER FLAME
BURNER
MANIFOLD
Table 12—Altitude Derate Multiplier for U.S.A.
ALTITUDE
(FT)
%OF
DERATE
DERATE MULTIPLIER
FACTOR FOR U.S.A.*
0—2000 0 1.00
2001—3000 4—6 0.95
3001—4000 6—8 0.93
4001—5000 8—10 0.91
5001—6000 10—12 0.89
6001—7000 12—14 0.87
7001—8000 14—16 0.85
8001—9000 16—18 0.83
9001—10,000 18—20 0.81
* Derate multiplier factor is based on midpoint altitude for altitude range.
47
To Next Page
Loading...
