Carrier WeatherMaker 8000 - Page 14

EXAMPLE: (0—2000 ft altitude)
Heating value = 1025 Btu/cu ft
Specific gravity = 0.62
Therefore: Orifice No. 43*
Manifold pressure 3.3-in. wc
* Furnace is shipped with No. 43 orifices. In this example
all main burner orifices are the correct size and do not need
to be changed to obtain proper input rate.
(7.) Check and verify burner orifice size in furnace.
NEVER ASSUME ORIFICE SIZE. ALWAYS
CHECK AND VERIFY.
b. Adjust manifold pressure to obtain input rate.
(1.) Remove regulator adjustment seal cap. (See Fig. 14.)
(2.) Turn adjusting screw, counterclockwise (out) to de-
crease manifold pressure or clockwise (in) to increase
manifold pressure.
NOTE: This furnace has been approved for a manifold pressure
of 3.2-in. wc to 3.8-in. wc when installed at altitudes up to 2000 ft.
For altitudes above 2000 ft, the manifold pressure can be adjusted
from 2.0-in. wc to 3.8-in. wc.
DO NOT bottom out gas valve regulator adjusting screw.
This can result in unregulated manifold pressure and result in
excess overfire and heat exchanger failures.
NOTE: If orifice hole appears damaged or it is suspected to have
been redrilled, check orifice hole with a numbered drill bit of
correct size. Never redrill an orifice. A burr-free and squarely
aligned orifice hole is essential for proper flame characteristics.
(3.) After correct manifold pressure is obtained, replace
gas valve regulator adjustment screw cap and verify
adjusted gas input rate using method outlined in item
c.
(4.) Burner flame should be clear blue, almost transparent.
(See Fig. 15.)
c. Verify natural gas input rate by clocking gas meter.
NOTE: High-Altitude Adjustment
United States
At installation altitudes above 2000 ft, this furnace has been
approved for a 4% derate for each 1000 ft above sea level. See
Table 7 for derate multiplier factor.
EXAMPLE:
88,000 Btuh input furnace installed at 4300 ft.
Furnace Input
Rate at
Sea Level
X
Derate
Multiplier
Factor
=
Furnace Input Rate
at Installation
Altitude
88,000 X 0.82 = 72,160
Canada
At installation altitudes from 2000 to 4500 ft, this furnace must be
derated 10% by an authorized Gas Conversion Station. To deter-
mine correct input rate for altitude, see example above and use
0.90 as derate multiplier factor.
a. Turn off all other gas appliances and pilots.
b. Start furnace and let operate for 3 minutes.
c. Measure time (in sec) for gas meter test dial to complete 1
revolution.
d. Refer to Table 8 for cu ft of gas per hr.
e. Multiply gas rate (cu ft/hr) X heating value (Btu/cu ft)
using natural gas heating value from local gas
utility/supplier.
EXAMPLE: (0—2000 ft altitude)
Btu heating input = Btu/cu ft X cu ft/hr
Heating value of gas = 1050 Btu/cu ft
Time for 1 revolution of 2-cu ft dial = 70 sec
Gas rate = 103 cu ft/hr (from Table 8)
Btu heating input = 103 X 1050 = 108,150 Btuh
In this example, the orifice size and manifold pressure
adjustment is within ±2 percent of the furnace input rate.
Table 6—Model 58WAV Orifice Size and Manifold Pressure for Correct Input Continued
(TABULATED DATA BASED ON 22,000 BTUH PER BURNER, DERATED 4% PER 1000 FT ABOVE SEA LEVEL)
ALTITUDE
RANGE
(FT)
AVG GAS
HEAT VALUE
AT ALTITUDE
(BTU/CU FT)
SPECIFIC GRAVITY OF NATURAL GAS
0.58 0.60 0.62 0.64 0.66
Orifice
No.
Manifold
Pressure
Orifice
No.
Manifold
Pressure
Orifice
No.
Manifold
Pressure
Orifice
No.
Manifold
Pressure
Orifice
No.
Manifold
Pressure
U.S.A. Only
575 43 2.7 43 2.8 43 2.9 43 3.0 43 3.1
600 43 2.5 43 2.6 43 2.7 43 2.7 43 2.8
9001 625 43 2.3 43 2.4 43 2.4 43 2.5 43 2.6
650 43 2.1 43 2.2 43 2.3 43 2.3 43 2.4
to 675 48 3.7 43 2.0 43 2.1 43 2.2 43 2.2
700 48 3.4 48 3.6 48 3.7 43 2.0 43 2.1
10,000 725 49 3.8 48 3.3 48 3.4 48 3.5 48 3.6
750 49 3.5 49 3.6 49 3.8 48 3.3 48 3.4
775 49 3.3 49 3.4 49 3.5 49 3.6 49 3.7
Table 7—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 8—12 0.90
3001—4000 12—16 0.86
4001—5000 16—20 0.82
5001—6000 20—24 0.78
6001—7000 24—28 0.74
7001—8000 28—32 0.70
8001—9000 32—36 0.66
9001—10,000 36—40 0.62
* Derate multiplier factor is based on midpoint altitude for altitude range.
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