Operating instructions

g. Look through sight glass in burner enclosure and check
burner flame. Burner flame should be clear blue, almost
transparent. (See Fig. 59.)
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 enclosure front are in place when checking input
by clocking gas meter.
TABLE 9—MODEL 350MAV ORIFICE SIZE AND MANIFOLD PRESSURE FOR CORRECT INPUT (CONTINUED)
FOR USE WITH 040 THROUGH 120 SIZE FURNACES ONLY
(TABULATED DATA BASED ON 20,000 BTUH PER BURNER, DERATED 2 PERCENT FOR EACH 1000 FT ABOVE SEA LEVEL)
ALTITUDE
RANGE
(FT)
AVG GAS
HEAT VALUE
(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. and Canada
4001
to
5000
9%
derate
750 43 3.4 43 3.5 43 3.7 43 3.8 42 3.2
775 44 3.7 44 3.8 43 3.4 43 3.5 43 3.7
800 44 3.5 44 3.6 44 3.7 44 3.8 43 3.4
825 44 3.2 44 3.4 44 3.5 44 3.6 44 3.7
850 45 3.7 45 3.8 44 3.3 44 3.4 44 3.5
875 45 3.5 45 3.6 45 3.7 44 3.2 44 3.3
900 45 3.3 45 3.4 45 3.5 45 3.6 45 3.8
925 45 3.1 45 3.2 45 3.3 45 3.4 45 3.6
950 45 3.0 45 3.1 45 3.2 45 3.3 45 3.4
ALTITUDE
RANGE
(FT)
AVG GAS
HEAT VALUE
(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. and Canada
5001
to
6000
11%
derate
725 43 3.4 43 3.5 43 3.6 43 3.7 43 3.8
750 44 3.6 44 3.7 43 3.4 43 3.5 43 3.6
775 44 3.4 44 3.5 44 3.6 44 3.7 43 3.4
800 44 3.2 44 3.3 44 3.4 44 3.5 44 3.6
825 45 3.6 45 3.7 44 3.2 44 3.3 44 3.4
850 45 3.4 45 3.5 45 3.6 45 3.8 44 3.2
875 45 3.2 45 3.3 45 3.4 45 3.6 45 3.7
900 45 3.0 45 3.1 45 3.3 45 3.4 45 3.5
925 45 2.9 45 3.0 45 3.1 45 3.2 45 3.3
950 45 2.7 45 2.8 45 2.9 45 3.0 45 3.1
975 45 2.6 45 2.7 45 2.8 45 2.9 45 2.9
1000 45 2.5 45 2.5 45 2.6 45 2.7 45 2.8
ALTITUDE
RANGE
(FT)
AVG GAS
HEAT VALUE
(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
6001
to
7000
13%
derate
675 43 3.6 43 3.7 43 3.8 42 3.2 42 3.3
700 44 3.8 43 3.4 43 3.6 43 3.7 43 3.8
725 44 3.6 44 3.7 44 3.8 43 3.4 43 3.5
750 44 3.3 44 3.4 44 3.6 44 3.7 44 3.8
775 45 3.8 44 3.2 44 3.3 44 3.4 44 3.5
800 45 3.5 45 3.7 45 3.8 44 3.2 44 3.3
825 45 3.3 45 3.4 45 3.6 45 3.7 45 3.8
850 45 3.1 45 3.2 45 3.4 45 3.5 45 3.6
875 45 3.0 45 3.1 45 3.2 45 3.3 45 3.4
* Orifice numbers 45 are factory installed.
Percents of derate are based on midpoints of U.S. altitude ranges.
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
—42—