Page 17
F- Proper Gas Flow (Approximate)
Furnace should operate at least 5 minutes before check
ing gas flow. Determine time in seconds for
two
revolu
tions of gas through the meter. (Two revolutions assures a
more accurate time.)
Divide by two
and compare to time
in table 8 below. If manifold pressure matches table 8 and
rate is incorrect, check gas orifices for proper size and re
striction.
NOTE- To obtain accurate reading, shut off all other gas
appliances connected to meter.
TABLE 8
GAS METER CLOCKING CHART
EL280DF
Unit
Seconds for One Revolution
Natural
LP
1 cu ft
Dial
2 cu ft
Dial
1 cu ft
Dial
2 cu ft
DIAL
-045
80
160
200
400
-70
55
110
136
272
-90
41
82
102
204
-110
33
66
82
164
-135
27
54
68
136
Natural-1000 btu/cu ft LP-2500 btu/cu ft
IMPORTANT
For safety, shut unit off and remove manometer as
soon as an accurate reading has been obtained.
Take care to replace pressure tap plug.
G- Proper Combustion
Furnace should operate minimum 15 minutes with correct
manifold pressure and gas flow rate before checking com
bustion. See sections E- and F-. Take combustion sample
beyond the flue outlet and compare to the table below. The
maximum carbon monoxide reading should not exceed
100 ppm.
TABLE 9
Firing Rate
CO
2
%
For Nat
CO
2
%
For L.P.
High Fire
6.0 - 7.5
7.0 - 8.5
Low Fire
5.0 - 6.5
5.8 - 7.3
The carbon monoxide reading should not exceed 100 ppm.
H-High Altitude
The manifold pressure, gas orifice and pressure switch
may require adjustment or replacement to ensure proper
operation at higher altitudes. See table 10 for manifold
pressures and table 11 for pressure switch kits and gas
conversion kits.
TABLE 10
Manifold Pressure Settings at all Altitudes
Unit
Input
Gas
Manifold
Pressure in.wg.
0-4500 ft.
Manifold
Pressure in.wg.
4501-7500 ft.
1
Manifold
Pressure in.wg.
7501 - 10,000 ft.
2
Supply Line
Pressure
in. w.g.
Low Fire
High Fire
Low Fire
High Fire
Low Fire
High Fire
Min
Max
070
Natural
1.7
3.5
1.5
3.2
1.7
3.5
4.5
13.0
LP/propane
3
4.9
10.0
4.9
10.0
4.9
10.0
11.0
13.0
090
Natural
1.7
3.5
1.5
3.0
1.7
3.5
4.5
13.0
LP/propane
3
4.9
10.0
4.9
10.0
4.9
10.0
11.0
13.0
110
Natural
1.7
3.5
1.5
3.2
1.7
3.5
4.5
13.0
LP/propane
3
4.9
10.0
4.9
10.0
4.9
10.0
11.0
13.0
1
This is the only permissible derate for these units.
2
Natural gas high altitude orifice kit required.
3
A natural to L.P. propane gas changeover kit is necessary to convert this unit. Refer to the changeover kit installation instruction for the conversion
procedure.
NOTE - Units may be installed at altitudes up to 4500 ft. above sea level without modifications.
TABLE 11
Pressure Switch and Gas Conversion Kits at all Altitudes
Unit
Input
High Altitude Pressure Switch Kit
High Altitude
Natural Gas Kit
LP/Propane Gas Kit
LP/Propane to
Natural Kit
0 - 4500 ft.
4501 - 7500 ft.
7501 - 10,000 ft.
7501 - 10,000 ft.
0 - 7500 ft
7501 - 10,000 ft.
0 - 7500 ft.Min
070
No Change
No Change
73W36
73W37
11K51
11K46
77W09
090
73W36
110
73W35
NOTE -
A natural to L.P. propane gas changeover kit is necessary to convert this unit. Refer to the changeover kit installation instruction for the conversion
procedure.
