York G8C05012MUB12 Quick start guide

TECHNICAL GUIDE
80 AFUE
MULTI-POSITION
GAS FURNACES
MODELS: G8C SERIES
4-POSITION
50-125 MBH INPUT
3-POSITION
150 MBH INPUT
EFFICIENCY
RATING
CERTIFIED
036-21120-002 Rev. A (1102)
FOR DISTRIBUTION USE ONLY - NOT TO BE USED AT POINT OF RETAIL SALE
®
DESCRIPTION
These compact units (31-1/2" high) employ induced combus-
tion, reliable electronic ignition and high heat transfer heat
exchangers. The units may be factory shipped for upflow/hor-
izontal application and converted for downflow application.
These units may also be factory shipped for downflow appli-
cation and converted for upflow/horizontal applications
Note: The 150 MBH input model is upflow/horizontal only and
may not be converted to the downflow position.
These furnaces are designed for residential installation in a
basement, closet, alcove, attic, or garage. All units are factory
assembled, wired and tested to assure safe dependable and
economical installation and operation.
These units are Category I listed and may be common vented
with another gas appliance as allowed by the National Fuel
Gas Code.
WARRANTY
20-year limited warranty on the heat exchanger.
5-year limited parts warranty.
FEATURES
• 4-position (MU) upflow models allow horizontal-left, hori-
zontal-right, downflow and convertible applications
• 4-position (MD) models allow downflow and convertible
upflow/horizontal applications
• 3-position (UH) 150 MBH input model allows upflow, hori-
zontal-left and horizontal-right application
• Reliable, hot surface ignitor
• Integrated control module for simplicity and reliable, eco-
nomical operation
• Built-in self-diagnostics with fault code display
• 100% shut off main gas valve for added safety
• Rollout safety control
• Low unit amp requirement for easy application
• High quality inducer motor for quiet operation
• 40 VA, fuse protected control transformer
• Terminals for controlling humidifiers and EAC’s
• Easy to connect power and control wiring
• Efficiency ratings of 80 AFUE
• Cooling blower relay supplied for easy installation of add-
on cooling
• Blower off-delay for cooling SEER improvement
• Multi-speed PSC, direct-drive blower motors to match
cooling requirements
• Adjustable fan-off settings to eliminate "cold-blow"
• Compact 31-1/2-in height allows installation in small space
confines
• All models are propane convertible
• Pre-painted exterior provides attractive, durable finish
• Models are not approved for LoNox applications

036-21120-002 Rev. A (1102)
2Unitary Products Group
FURNACE DIMENSIONS
** 3-Position 150 MBH model available only in upflow/horizontal (UH) configuration.
Dimensions "B", "C", "D" & "E" are with duct flanges turned up. "F", "G", "H" & "J" are with flanges flat.
RATINGS & PHYSICAL/ELECTRICAL DATA
** 3-Position 150 MBH model available only in upflow/horizontal (UH) configuration.
NOTE: For altitudes above 2,000 ft., reduce capacity 4% for each 1,000 ft. above sea level.
Wire size based on copper conductors, 60° C, 3% voltage drop.
Continuous return air temperature must not be below 55° F.
DOWNFLOW UPFLOW
AA
BE
D
BOTTOM VIEW
F
G
29-3/4 29-3/4
C
31-1/2
31-1/2
14
BOTTOM VIEW
H
J
16-1/4
K
K
Model ABCDEFGHJK(Vent)
G8C05012(MU,MD)B12
1
17-1/2 16-1/2 20-3/8 20 16 14-3/4 18-3/4 15-1/8 19 3
G8C07512(MU,MD)B12
1
17-1/2 16-1/2 20-3/8 20 16 14-3/4 18-3/4 15-1/8 19 4
2
G8C07516(MU,MD)C12
1
21 20 20-3/8 20 19-1/2 18-1/4 18-3/4 18-5/8 19 4
2
G8C10016(MU,MD)C12
1
21 20 20-3/8 20 19-1/2 18-1/4 18-3/4 18-5/8 19 4
2
G8C10020(MU,MD)D11
1
24-1/2 23-1/2 20-3/8 20 23 21-3/4 18-3/4 22-1/8 19 4
2
G8C12520(MU,MD)D11
1
24-1/2 23-1/2 20-3/8 20 23 21-3/4 18-3/4 22-1/8 19 5
2
G8C15020UHD11** 24-1/2 23-1/2 20-3/8 20 23 21-3/4 18-3/4 22-1/8 19 5
2
1. 4-Position models may be factory configured as upflow (MU) or downflow (MD) models.
2. All models are supplied with 3" vent connections. An installer supplied transition to 4" or 5" must be used where necessary.
Model
Heat
Cap.
Input
MBH
Output
MBH
Air Temp
Rise °F
Max.
Outlet
Temp. °F
Blower Total
Unit
Amps
Max.
Over-
Current
Breaker
Min. Wire
Size (AWG)
@ 75 Ft.
One Way
HP Size
G8C05012(MU,MD)B12
1
50 40 30-60 160 1/3 10 x 8 6.7 15 14
G8C07512(MU,MD)B12
1
75 60 35-65 165 1/3 10 x 8 6.7 15 14
G8C07516(MU,MD)C12
1
75 60 30-60 160 1/2 10 x 10 8.5 15 14
G8C10016(MU,MD)C12
1
100 80 40-70 170 1/2 10 x 10 8.5 15 14
G8C10020(MU,MD)D11
1
100 80 35-65 165 3/4 (2) 10 x 6 10.3 15 14
G8C12520(MU,MD)D11
1
125 100 40-70 170 3/4 (2) 10 x 6 10.3 15 14
G8C15020UHD11** 150 120 40-70 170 3/4 (2) 10 x 6 10.3 15 14
1. 4-Position models may be factory configured as upflow (MU) or downflow (MD) models.

036-21120-002 Rev. A (1102)
Unitary Products Group 3
BLOWER PERFORMANCE
TABLE 1: SINGLE SIDE RETURN -
All airflow is expressed in standard cubic feet per minute. Motor rated at 115 volts. No air filters.
MODEL SPEED
TAP
EXTERNAL STATIC PRESSURE, INCHES W.C.
0.10.20.30.40.50.60.70.8
G8C05012(MU,MD)B12
HIGH 1411 1360 1289 1218 1154 1075 983 882
MEDIUM 1213 1177 1134 1085 1022 960 880 782
LOW 887 884 871 848 814 775 726 656
G8C07512(MU,MD)B12
HIGH 1535 1470 1408 1343 1275 1202 1115 1014
MEDIUM 1215 1199 1182 1151 1106 1039 976 887
LOW 875 874 864 847 827 799 736 658
G8C07516(MU,MD)C12
HIGH 1792 1724 1630 1552 1462 1367 1264 1152
MEDIUM 1597 1555 1496 1444 1372 1287 1190 1086
LOW 1115 1140 1167 1183 1149 1093 1023 939
G8C10016(MU,MD)C12
HIGH 1868 1781 1690 1600 1498 1396 1277 1156
MEDIUM 1602 1553 1503 1447 1376 1287 1181 1060
LOW 1147 1147 1147 1147 1132 1078 1009 918
G8C10020(MU,MD)D11
HIGH
NOT APPROVED
MED. HI
MED.LO
LOW
G8C12520(MU,MD)D11
HIGH
MED. HI
MED.LO
LOW
G8C15020UHD11
HIGH
MED. HI
MED.LO
LOW
TABLE 2: DUAL RETURN (TWO SIDES OR ONE SIDE & BOTTOM)-
All airflow is expressed in standard cubic feet per minute. Motor rated at 115 volts. No air filters.
MODEL SPEED
TAP
EXTERNAL STATIC PRESSURE, INCHES W.C.
0.10.20.30.40.50.60.70.8
G8C05012(MU,MD)B12
HIGH 1507 1433 1371 1300 1223 1132 1040 938
MEDIUM 1239 1215 1175 1144 1085 1012 938 838
LOW 907 907 891 875 849 800 741 672
G8C07512(MU,MD)B12
HIGH 1634 1562 1484 1417 1340 1238 1154 1030
MEDIUM 1243 1228 1214 1184 1133 1079 999 912
LOW 886 886 886 886 865 823 777 700
G8C07516(MU,MD)C12
HIGH 1978 1896 1803 1693 1589 1478 1366 1235
MEDIUM 1682 1657 1606 1530 1455 1366 1265 1137
LOW 1235 1235 1235 1235 1198 1154 1083 987
G8C10016(MU,MD)C12
HIGH 2122 2027 1916 1821 1717 1590 1462 1312
MEDIUM 1667 1696 1656 1597 1523 1438 1330 1191
LOW 1130 1145 1177 1194 1181 1146 1077 982
G8C10020(MU,MD)D11
HIGH 2297 2200 2088 1980 1873 1753 1610 1453
MED. HI 1712 1677 1608 1551 1483 1380 1278 1147
MED.LO 1569 1569 1501 1453 1420 1323 1211 1088
LOW 1439 1439 1416 1369 1307 1218 1121 1004
G8C12520(MU,MD)D11
HIGH 2377 2303 2207 2106 1983 1864 1717 1557
MED. HI 1704 1684 1656 1614 1542 1458 1361 1228
MED.LO 1524 1520 1512 1467 1418 1353 1266 1142
LOW 1368 1395 1391 1386 1343 1262 1188 1072
G8C15020UHD11
HIGH 2426 2336 2246 2143 2023 1897 1766 1590
MED. HI 1654 1654 1619 1591 1533 1456 1342 1199
MED.LO 1528 1528 1503 1467 1417 1340 1238 1107
LOW 1395 1374 1369 1325 1288 1231 1177 1071

036-21120-002 Rev. A (1102)
4Unitary Products Group
RETURN AIR AND FILTERS
The return air ducts to the furnace must have a total cross
sectional area of not less than two square inches per 1000
BTUH of furnace input rating for heating operation. If air con-
ditioning is to be installed with the furnace, or if it may be
added at a later time, larger return air ducts may be
required, depending on the capacity of the air condi-
tioner and the airflow required.
RECOMMENDED FILTER SIZE/ADD-ON COOLING
TABLE 3: BOTTOM END RETURN -
All airflow is expressed in standard cubic feet per minute. Motor rated at 115 volts. No air filters.
MODEL SPEED
TAP
EXTERNAL STATIC PRESSURE, INCHES W.C.
0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8
G8C05012(MU,MD)B12
HIGH 1419 1357 1297 1212 1131 1050 942 846
MEDIUM 1221 1185 1145 1092 1036 961 879 780
LOW 920 902 883 860 818 761 711 639
G8C07512(MU,MD)B12
HIGH 1552 1491 1420 1348 1271 1185 1080 970
MEDIUM 1229 1237 1198 1164 1105 1039 956 861
LOW 889 892 879 866 846 807 760 689
G8C07516(MU,MD)C12
HIGH 1946 1862 1775 1620 1518 1409 1291 1160
MEDIUM 1683 1611 1551 1484 1388 1300 1190 1080
LOW 1110 1138 1175 1190 1175 1126 1041 937
G8C10016(MU,MD)C12
HIGH 1997 1920 1822 1723 1620 1500 1355 1211
MEDIUM 1728 1679 1635 1556 1465 1359 1249 1117
LOW 1131 1156 1181 1190 1171 1126 1049 926
G8C10020(MU,MD)D11
HIGH 2195 2097 2013 1915 1798 1680 1549 1393
MED. HI 1753 1707 1666 1597 1509 1423 1307 1188
MED.LO 1631 1594 1526 1462 1400 1303 1204 1079
LOW 1477 1444 1407 1360 1293 1222 1132 1016
G8C12520(MU,MD)D11
HIGH 2347 2248 2160 2041 1926 1798 1646 1494
MED. HI 1740 1700 1666 1596 1524 1447 1349 1216
MED.LO 1596 1578 1561 1503 1442 1353 1257 1117
LOW 1460 1431 1398 1372 1323 1254 1155 1024
G8C15020UHD11
HIGH 2414 2327 2216 2099 1998 1876 1736 1569
MED. HI 1717 1717 1670 1621 1555 1472 1375 1242
MED.LO 1544 1544 1516 1488 1431 1348 1241 1140
LOW 1431 1393 1397 1354 1314 1235 1144 1035
For applications requiring more than 1800 CFM, it
is required to use the bottom return, both side
returns or one side plus the bottom return.
• Single side return is not approved on 5 Ton mod-
els.
• 18” minimum height for return air box for bottom
return only on Heating only applications with fur-
nace in the upflow configuration.
• 24” minimum height for return air box for bottom
return only on A/C applications with furnace in
the upflow configuration.
Upflow / Horz.
Models
Filter Size Add-on Cooling Approx. Oper.
Weight
Side
1
1. All filters must be external to the cabinet.
Bottom / End Downflow Tons CFM @ .5 ESP
2
2. ESP (External Static Pressure) .5” W.C. is at furnace outlet ahead of cooling coil.
Filters must be field supplied.
High velocity type must be used.
Air flows above 1800 CFM require either return from two sides or bottom.
G8C05012(MU,MD)B12 25 x 16 24 x 15 (2) 10 x 20 2, 2-1/2, 3 1200 112
G8C07512(MU,MD)B12 25 x 16 24 x 15 (2) 14 x 20 2, 2-1/2, 3 1200 118
G8C07516(MU,MD)C12 25 x 16 24 x 18 (2) 16 x 20 2-1/2, 3, 3-1/2, 4 1600 129
G8C10016(MU,MD)C12 25 x 16 24 x 18 (2) 16 x 20 2-1/2, 3, 3-1/2, 4 1600 135
G8C10020(MU,MD)D11 (2) 25 x 16 24 x 21 (2) 20 x 20 3, 3-1/2, 4, 5 2000 149
G8C12520(MU,MD)D11 (2) 25 x 16 24 x 21 (2) 20 x 20 3, 3-1/2, 4, 5 2000 155
G8C15020UHD11 (2) 25 x 16 24 x 21 N/A 3, 3-1/2, 4, 5 2000 165

036-21120-002 Rev. A (1102)
Unitary Products Group 5
APPLYING FILTER PRESSURE DROP TO
DETERMINE SYSTEM AIRFLOW
To determine the approximate airflow of the unit with a filter in
place, follow the steps below:
1. Select the filter type.
2. Select the number of return air openings or calculate the
return opening size in square inches to determine the
proper filter pressure drop.
3. Determine the External System Static Pressure (ESP)
without the filter.
4. Select a filter pressure drop from the table based upon
the number of return air openings or return air opening
size and add to the ESP from Step 3 to determine the
total system static.
5. If total system static matches a ESP value in the airflow
table (i.e. 0.20, 0.60, etc.,) the system airflow corre-
sponds to the intersection of the ESP column and Model/
Blower Speed row.
6. If the total system static falls between ESP values in the
table (i.e. 0.58, 0.75, etc.), the static pressure may be
rounded to the nearest value in the table determining the
airflow using Step 5 or calculate the airflow by using the
following example.
Example: For a 100,000 BTUH furnace with 2 return open-
ings and operating on high speed blower, it is found that total
system static is 0.58" w.c. To determine the system airflow,
complete the following steps:
1. Obtain the airflow values at 0.50" & 0.60" ESP.
Airflow @ 0.50": 1717 CFM
Airflow @ 0.60": 1590 CFM
2. Subtract the airflow @ 0.50" from the airflow @ 0.60" to
obtain airflow difference.
1590 - 1717 = -127 CFM
3. Subtract 0.50” from the total system static, and divide
this difference by the difference in ESP values in the
table, 0.60" - 0.50", to obtain a percentage.
(0.58 - 0.50) / (0.60 - 0.50) = 0.8
4. Multiply percentage by airflow difference to obtain airflow
reduction.
(0.8)x(-127) = -102
5. Subtract airflow reduction value from airflow @ 0.50" to
obtain actual airflow @ 0.58" ESP.
1717 - 102 = 1615
TABLE 4: FILTER PERFORMANCE - PRESSURE DROP INCHES W.C.
Airflow Range
Minimum Opening Size
(in.
2
)
Filter Type
Disposable Hogs Hair Pleated
1 Opening 2 Openings 1 Opening 2 Openings 1 Opening 2 Openings 1 Opening 2 Openings
0 - 750 230 0.01 0.01 0.15
751 - 1000 330 0.05 0.05 0.20
1001 - 1250 330 0.10 0.10 0.20
1251 - 1500 330 0.10 0.10 0.25
1501 - 1750 380 658 0.15 0.09 0.14 0.08 0.30 0.17
1751 - 2000 380 658 0.19 0.11 0.18 0.10 0.30 0.17
2001 & Above 463 658 0.19 0.11 0.18 0.10 0.30 0.17

036-21120-002 Rev. A (1102)
6Unitary Products Group
UNIT CLEARANCES TO COMBUSTIBLES
NOTE:1. Special floor base or air conditioning coil required for use on combustible floor.
NOTE:2. Line contact only permitted between lines formed by the intersection of the rear panel and side panel (top in horizontal position) of the furnace jacket and
building joists, studs or framing.
*Cabinet clearance is "0", vent clearance is required.
ACCESSORIES
Propane Conversion Kit (Standard) – 1NP0366
This accessory conversion kit may be used to convert natural
gas units for propane (LP) operation at altitudes 0-2,000 ft.
Conversion must be made by qualified distributor or dealer
personnel.
Propane Conversion Kit (High Altitude) – 1NP0367
This accessory conversion kit may be used to convert natural
gas units for propane (LP) operation at altitudes from 2,000 to
8,000 ft. Conversion must be made by qualified distributor or
dealer personnel.
Combustible Floor Base
This accessory is used for downflow applications on combus-
tible surfaces.
17-1/2" "B" Cabinets 1FB0318
21" "C" Cabinets 1FB0319
24-1/2" "D" Cabinets 1FB0320
Bottom External Filter Rack
This accessory is used to upflow/bottom return air applica-
tions. Packaged and sold in quantities of six (6).
17-1/2" "B" Cabinets 1BR0312BK
21" "C" Cabinets 1BR0316BK
24-1/2" "D" Cabinets 1BR0320BK
Application Top Front Rear Left Side Right
Side Flue Floor / Bottom Closet Alcove Attic Line Contact
UPFLOW 1 6 0 0 0 6 COMBUSTIBLE YES YES YES NO
UPFLOW
B-VENT 1 2 0 0 0 1 COMBUSTIBLE YES YES YES NO
HORIZONTAL 0 6 0 0 1 6 COMBUSTIBLE NO YES YES YES(See Note
2
)
HORIZONTAL
B-VENT 1 2 0 0 1 1 COMBUSTIBLE NO YES YES YES(See Note
2
)
DOWNFLOW 1 6 0 0 5* 6 1" (See Note
1
)YES YES YES NO
DOWNFLOW
B-VENT 12 0 0 01
1" (See Note
)
YES YES YES NO

036-21120-002 Rev. A (1102)
Unitary Products Group 7
NOTES

Subject to change without notice. Printed in U.S.A. 036-21120-002 Rev. A (1102)
Copyright © by York International Corp. 2002. All rights reserved. Supersedes: 036-21120-001 Rev. A (0201)
Unitary 5005 Norman
Products York OK
Group Drive 73069