FIRING RATE SELECTION
All units are capable of firing at a tow or high rate. Check the unit
name-plate, to verify the firing rate of the unit as shipped from the
factory.
If the other input rate is desired, the conversion is made as follows:
1. Be sure the unit disconnect is open.
2. Be sure the gas valve is closed.
3. Remove furnace access panel.
4. Remove the presently installed gas orifices and replace with
the new gas orifices from the tow fire kit. The orifices should extend
1/4 inch out of the manifold for burner support.
5. For tow fire operation an OUTLET FLUE RESTRICTOR
(packed in the tow fire kit) mustbe installed (see Figure 16 on page
14). For high fire operation on a few models a different OUTLET
FLUE RESTRICTOR may have been required.
6. Reinstall the furnace access panel.
7. Open the gas valve.
8. Close the unit disconnect.
9. Follow the heating cycle instructions to test unit's function.
10. Mark an "X" below the new input column on unit nameplate.
Attach conversion label to the unit below the nameplate.
NOTE: Do not convert to high fire when the units are applied above
2000 feet above seal level.
INPUT CHECK AND ADJUSTMENT
1. Make sure all gas appliances are off except the furnace.
2. Clock the gas meter with the furnace operating (determine the
dial rating of the meter) for one revolution.
3. Match the "Sec" column in the gas flow (in cfh) Table 3 with the
time clocked.
4. Read the "Flow" column opposite the number of seconds
clocked.
5. Use the following factors if necessary.
For 1 Cu. Ft. Dial Gas Flow CFH =
Chart Flow Reading / 2
For 1/2 Cu Ft. Dial Gas Flow CFH =
Chart Flow Reading / 4
For 5 Cu. Ft. Dial Gas Flow CFH =
10X Chart Flow Reading / 4
6. Multiply the final figure by the heating value of the gas obtained
from the utility company and compare to the nameplate rating.
This must not exceed the nameplate rating.
7. Changes can be made by adjusting the manifold pressure.
a. Attach a manifold pressure gauge.
b. Remove the slot screw on top of the gas valve for 1st stage
manifold pressure adjustment.
c. Turn the adjustment nut IN to increase the gas flow rate, and
OUT to decrease the gas flow rate using a 3/32" hex wrench.
TABLE 3
GAS FLOW IN CUBIC FEET PER HOUR
2 CUBIC FOOT DIAL
Sec. Flow Sec. Flow Sec. Flow Sec. Flow
8 900 29 248 50 144 82 88
9 800 30 240 51 141 84 86
10 720 31 232 52 138 86 84
11 655 32 225 53 136 88 82
12 600 33 218 54 133 90 80
13 555 34 212 55 131 92 78
14 514 35 206 56 129 94 76
15 480 36 200 57 126 96 75
16 450 37 195 58 124 98 73
17 424 38 189 59 122 100 72
18 400 39 185 60 120 104 69
19 379 40 180 62 116 108 67
20 360 41 176 64 112 112 64
21 343 42 172 66 109 116 62
22 327 43 167 68 106 120 60
23 313 44 164 70 103 124 58
24 300 45 160 72 100 128 56
25 288 46 157 74 97 132 54
26 277 47 153 76 95 136 53
27 267 48 150 78 92 140 51
28 257 49 147 80 90 144 50
HIGH ALTITUDE INSTALLATION
Unit nameplate ratings are based on equipment operation from sea
level to 2000 feet elevation above sea level. If the unit installation
isfrom 2000 - 4500 feet elevation, it will be necessary to change the
burner orifices to the noted sizes, (ref. National Fuel Gas Code, sec
8.1.2, Appendix F, Table F4).
GAS
TYPE
NATURAL
( high input )
NATURAL
( low input )
PROPANE
MANIFOLD
PRESSURE
(in. W.C. )
3.3
3.3
10.0
ORIFICE SIZE
0 - 2000 ft
42 _
44
54
ORIFICE SIZE
2000-4500
43
45
55
FACTORY SHIPPED
Page 15
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