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272312-UIM-A-0407

6

Unitary Products Group

RESIDENTIAL AND MODULAR HOME UPFLOW 

RETURN PLENUM CONNECTION

Return air may enter the furnace through the side(s) or bottom depend-
ing on the type of application. Return air may not be connected into the
rear panel of the unit. In order to achieve the airflow indicated, it is rec-
ommended those applications over 1800 CFM (51 m³/min) use return
air from two sides, one side and the bottom or bottom only. For single
return application, see data and notes on blower performance data
tables in this manual.

BOTTOM RETURN AND ATTIC INSTALLATIONS

Bottom return applications normally pull return air through a base plat-
form or return air plenum. Be sure the return platform structure or return
air plenum is suitable to support the weight of the furnace.

The furnace base is equipped with a rectangular blockoff panel that can
be removed by performing the following steps:

1.

Lay the furnace on its back.

2.

Remove the screws from the toe plate.

3.

Remove the toe plate.

4.

Pull the base plate out of the furnace base.

5.

Reinstall the toe plate and secure with the screws that were
removed.

Attic installations must meet all minimum clearances to combustibles
and have floor support with required service accessibility.

IMPORTANT: 

If an external mounted filter rack is being used see the

instructions provided with that accessory for proper hole cut size.

HORIZONTAL MODELS

IMPORTANT: 

This furnace may be installed in a horizontal position on

either side as shown above. 

It must not be installed on its back.

 FIGURE 1:  

Dimensions

A

40

26-1/2

1-1/2

1-1/4

C

20

5/8

5/8

B

24-3/4

FRONT

BOTTOM IMAGE

RETURN END

TOP IMAGE

SUPPLY END

D

4” Diameter

LEFT SIDE

RIGHT SIDE

20

30-1/8

14-3/4

5-3/8

(VENT CONNECTION)

POWER WIRING
7/8” HOLE

2-1/2

ACCESS
WIRING
7/8” K.O.

16

8-3/4

T’STAT WIRING
7/8” K.O.

1-1/8

2-1/4

14

23-1/2

32-1/2

2

13-3/4

GAS INLET
1-1/4 x 2-1/2

B

4” Diameter

3/4

TABLE 4: 

Cabinet and Duct Dimensions

BTUH Input

CFM (m

3

/min)

Cabinet

Size

Cabinet Dimension

MBH

kW

A

A (cm)

B

B (cm)

C

C (cm)

D

D (cm)

40/26

11.7/7.6

1200 (33.98)

A

14 1/2

36.8

13 1/4

33.6

11 1/2

29.2

10 1/8

25.7

57/42

17.6/12.3

1200 (33.98)

A

14 1/2

36.8

13 1/4

33.6

11 1/2

29.2

10 1/8

25.7

80/59

23.4/17.3

1200 (33.98)

A

14 1/2

36.8

13 1/4

33.6

11 1/2

29.2

10 1/8

25.7

80/59

23.4/17.3

1600 (45.31)

B

17 1/2

44.4

16 1/4

41.3

14 1/2

36.8

11 5/8

29.5

80/59

23.4/17.3

1600 (45.31)

C

21

53.3

19 3/4

50.2

18

45.7

13 3/8

34

100/65

29.3/19.1

1200 (33.98)

B

17 1/2

44.4

16 1/4

41.3

14 1/2

36.8

11 5/8

29.5

100/65

29.3/19.1

2000 (56.63)

C

21

53.3

19 3/4

50.2

18

45.7

13 3/8

34

120/78

35.2/22.9

1600(45.31)

C

21

53.3

19 3/4

50.2

18

45.7

13 3/8

34

120/78

35.2/22.9

2000 (56.63)

C

21

53.3

19 3/4

50.2

18

45.7

13 3/8

34

Summary of Contents for FC8T-UH

Page 1: ...DJUSTMENTS 22 WIRING DIAGRAM 30 LIST OF FIGURES Dimensions 6 Typical Attic Installation 7 Typical Suspended Furnace Crawl Space Installation 7 Side Return Cutout Markings 8 Gas Valve 8 Upflow Gas Pipi...

Page 2: ...s from combustible materials as listed under Clearances to Combustibles in Table 1 Provide clearances for servicing ensuring that service access is allowed for both the burners and blower These models...

Page 3: ...d Never store items such as the following on near or in contact with the fur nace 1 Spray or aerosol cans rags brooms dust mops vacuum cleaners or other cleaning tools 2 Soap powders bleaches waxes or...

Page 4: ...t the specified external static pressure and within the air temperature rise specified on the nameplate Table 2 is a guide for determining whether the rectangular duct system that the furnace is being...

Page 5: ...plenum On all installations without a coil a removable access panel is recommended in the outlet duct such that smoke or reflected light would be observable inside the casing to indi cate the presenc...

Page 6: ...essibility IMPORTANT If an external mounted filter rack is being used see the instructions provided with that accessory for proper hole cut size HORIZONTAL MODELS IMPORTANT This furnace may be install...

Page 7: ...removed and a new plenum installed that is the proper size for the new furnace Attach the return plenum to the furnace inlet duct flanges This is typi cally through the use of S cleat material when a...

Page 8: ...fer to Table 15 SECTION IV GAS PIPING GAS SAFETY IMPORTANT Plan your gas supply before determining the correct gas pipe entry Use 90 degree service elbow s or short nipples and con ventional 90 degree...

Page 9: ...e gas valve body is a very thin casting that cannot take any external pressure Never apply a pipe wrench to the body of the gas valve when installing piping A wrench must be placed on the octag onal h...

Page 10: ...o the proper gas orifice size when the furnace is installed Do not attempt to drill out any orifices to obtain the proper orifice size Drilling out a gas orifice will cause misalignment of the burner...

Page 11: ...ty is corrected Refer to FURNACE DIAGNOSTICS section of the User s Information Maintenance Service Manual provided with this furnace for symptoms of reversed power supply polarity LOW VOLTAGE CONTROL...

Page 12: ...lt Common is optional when used with batteries Thermostat Installer Setup Number 1 System Type must be set to 6 2 Heat 2 Cool Conventional R 24 Volt Hot Heat XFMR W2 Second Stage Heat RC 24 Volt Hot C...

Page 13: ...BSG Bonnet Sensor Bonnet Sensor Optional BS Bonnet Sensor W2 Second Stage Auxiliary Heat W2 Second Stage Auxiliary Heat AUX Auxiliary Heat E W1 First Stage Auxiliary Heat E W1 First Stage Auxiliary H...

Page 14: ...gas supplies must be provided as specified with these instruc tions Since the furnaces are side by side with no space between gas supplies must enter on the right and left respectively All gas piping...

Page 15: ...wers will come on in the selected continuous fan speed and will stay on until the G signal is removed SECTION VI VENT SYSTEM VENT SAFETY This Category I furnace is designed for residential application...

Page 16: ...ese instructions Approved Modular Homes must be vented with an approved roof jack and may not be common vented with other appliances VENTING Category I venting consists of vertically venting one or mo...

Page 17: ...se masonry chimney kits 3 The chimney must extend at least three 3 ft 0 91 cm above the highest point where it passes through a roof of a building and at least two 2 feet higher than any portion of th...

Page 18: ...tion should be located where it will not be affected by wind gusts light snow airborne leaves or allow recirculation of flue gases 4 Termination should be located where it will not be damaged or expos...

Page 19: ...anufacturer s instructions Dampers Louvers and Grilles Canada Only 1 The free area of a supply air opening shall be calculated by sub tracting the blockage area of all fixed louvers grilles or screens...

Page 20: ...horizontally from the burner level of the appliance Refer to COMBUSTION AIR SOURCE FROM OUTDOORS and VENT AND SUPPLY AIR SAFETY CHECK in these instructions for additional information and safety check...

Page 21: ...mounted on the burner assembly If the temperature around the burner exceeds the set point the ignition control and the gas valve are de energized The operation of this control indicates a malfunction...

Page 22: ...m Source 1 which has the following items 1 12 30 cm length x 1 8 0 3 cm diameter tubing 2 pieces of 4 10 cm length x 1 8 0 3 cm diameter tubing 1 5 16 0 8 cm tee 1 5 16 0 8 cm x 1 8 3 175 mm reducing...

Page 23: ...at the gas meter times a barometric pressure and temperature correction factor of 0 960 times 3600 then divided by the time it took to measure 0 10 m3 of gas from the gas meter For Propane LP Gas mul...

Page 24: ...h low and high have been calibrated at the factory Additional pressure adjustment should not be necessary If adjustment is necessary set to the following specifications After adjustment check for gas...

Page 25: ...eration Start the system by setting the thermostat above the room temperature Observe the system s response Then use the troubleshooting section in this manual to check the system s operation FURNACE...

Page 26: ...mit switch has opened its normally closed contacts and has remained open for more than five minutes This condition is usually caused by a failed blower motor or blower wheel 12 RED FLASHES This code i...

Page 27: ...the difference in ESP values in the table 0 60 w c 150 Pa 0 50 w c 125 Pa to obtain a percentage 0 58 0 50 0 60 0 50 0 8 Multiply percentage by airflow difference to obtain airflow reduction 0 8 X 70...

Page 28: ...50 1440 1430 1390 1360 1310 1270 1220 1150 41 6 41 1 40 8 40 5 39 4 38 5 37 1 36 0 34 5 32 6 Low 1260 1260 1260 1260 1250 1200 1150 1110 1070 1010 35 7 35 7 35 7 35 7 35 4 34 0 32 6 31 4 30 3 28 6 80...

Page 29: ...640 1550 1460 56 6 55 5 54 7 53 8 51 0 49 8 48 4 46 4 43 9 41 3 Medium 1440 1440 1430 1420 1400 1380 1340 1300 1220 1150 40 8 40 8 40 5 40 2 39 6 39 1 37 9 36 8 34 5 32 6 Low 1220 1230 1230 1230 1200...

Page 30: ...272312 UIM A 0407 30 Unitary Products Group SECTION IX WIRING DIAGRAM FIGURE 31 Wiring Diagram...

Page 31: ...272312 UIM A 0407 Unitary Products Group 31 NOTES...

Page 32: ...t to change without notice Printed in U S A 272312 UIM A 0407 Copyright by York International Corp 2007 All rights reserved Supersedes 167185 UIM C 0806 Unitary 5005 Norman Product York OK Group Drive...

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