American Standard YCP-IOM-1C Installation Operation & Maintenance page 15

All units are capable of firing at a low 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 low fire kit. The orifices should extend
1/4 inch out of the manifold for burner support.
5. For low fire operation an OUTLET FLUE RESTRICTOR
(packed in the low fire kit) must be 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.
Dwg. No. X664209 P01
FIRING RATE SELECTION
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
8 900 29 248
9 800 30 240
10 720 31 232
11 655 32 225
12 600 33 218
13 555 34 212
14 514 35 206
15 480 36 200
16 450 37 195
17 424 38 189
18 400 39 185
19 379 40 180
20 360 41 176
21 343 42 172
22 327 43 167
23 313 44 164
24 300 45 160
25 288 46 157
26 277 47 153
27 267 48 150
28 257 49 147
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
is from 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).
MANIFOLD
GAS
PRESSURE
TYPE
( in. W.C. )
NATURAL
3.3
( high input )
NATURAL
3.3
( low input )
PROPANE 10.0
*
FACTORY SHIPPED
Sec. Flow Sec. Flow
50 144 82 88
51 141 84 86
52 138 86 84
53 136 88 82
54 133 90 80
55 131 92 78
56 129 94 76
57 126 96 75
58 124 98 73
59 122 100 72
60 120 104 69
62 116 108 67
64 112 112 64
66 109 116 62
68 106 120 60
70 103 124 58
72 100 128 56
74 97 132 54
76 95 136 53
78 92 140 51
80 90 144 50
ORIFICE SIZE ORIFICE SIZE
0 - 2000 ft 2000 - 4500 ft
*
43
42
44 45
54 55
Page 15