Bryant 581B User Manual

installation, start-up and service instructions

SINGLE PACKAGE ROOFTOP GAS HEATING/ELECTRIC COOLING UNITS

CONTENTS

Page

SAFETY CONSIDERATIONS . . . . . . . . . . . . . . . . . . . . . . . . . 1

INSTALLATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-33

I. Step 1 — Provide Unit Support. . . . . . . . . . . . . . . . . 1

II. Step 2 — Field Fabricate Ductwork . . . . . . . . . . . . . 2

III. Step 3 — Determine Location of Drain Line

and External Trap. . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

IV. Step 4 — Rig and Place Unit. . . . . . . . . . . . . . . . . . . 4

V. Step 5 — Install Flue Hood . . . . . . . . . . . . . . . . . . . . 4

VI. Step 6 — Install Gas Piping . . . . . . . . . . . . . . . . . . . 4

VII. Step 7 — Make Electrical Connections . . . . . . . . . . 9

VIII. Step 8 — Adjust Factory-Installed Options. . . . . . 13

IX. Step 9 — Adjust Evaporator-Fan Speed . . . . . . . . 22

PRE-START-UP. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34

START-UP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .34-37

SERVICE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .38-44

TROUBLESHOOTING. . . . . . . . . . . . . . . . . . . . . . . . . . . .45-49

INDEX . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50

START-UP CHECKLIST . . . . . . . . . . . . . . . . . . . . . . . . . . CL-1

SAFETY CONSIDERATIONS

Installation and servicing of air-conditioning equipment can be hazardous due to system pressure and electrical components. Only trained and qualified service personnel should install, repair, or servic e air-conditioning equipment.

Untrained personnel can perform basic maintenance functions of cleaning coils and filters and replacing filters. All other operations should be p erformed by tra ined servic e personnel. When working on air-conditioning equipment, observe precautions in the literature, tags and labels attached to the unit, and other safety precautions that may apply.

Follow all safety codes. Wear safety glasses and work gloves. Use quenching cloth for unbrazing operations. Have fire extinguishers available for al l brazing operations.

CAUTION: Ensure voltage listed on unit data plate

agrees with electrical supply provided for the unit.

WARNING: Disconnect gas piping from unit when leak testing at pressure greater than greater than ing in hazardous condition. If gas valve is subjected to pressure greater than use. When pressure testing field-supplied gas piping at pressures of piping must be isolated by manually closing the gas valve(s).

/2 psig will cause gas valve damage result-

psig, it must be replaced before

/2 psig or less, a unit connected to such

/2 psig. Pressures

581B

Dura

Cancels: II 581B-36-6 II 581B-36-7

WARNING: Before performing service or maintenance operatio ns on u nit , tu rn of f ma i n po wer sw itch to unit. Electrical shock could cause personal injury.

Unit is shipped in the vertical configuration. To convert to horizontal application, remove side duct opening covers. Using the same screws, insta ll covers on vertical duct o penings with the insulation-side down. Seals around duct openings must be tight. See Fig. 1.

I. STEP 1 — PROVIDE UNIT SUPPORT

A. Roof Curb

Assemble and install acce ssory roof curb in accordance with instructions shipped with cu rb. See Fig. 2. Install insulati on, cant strips, roofing felt, and cou nter fla shin g as sh own. Duct- work must be attached to curb. If gas is to be routed through the curb, attach the accessory thru-the-curb service connection plate to the ro of curb in accordance with the a ccessory installation instructions. Connection plate must be installed before unit is set in roof curb.

IMPORTANT: The gasketing of the unit to the roof curb is critical for a watert ight seal . Inst all gas ket suppl ied with t he roo f curb as shown in Fig. 2. Improperly applied gasket can also result in air or water leaks and poor unit performance.

Curb should be leve l. Th is is ne ce ss ary f or un it d ra in t o func tion properly. Unit leveling tolerances are shown in Fig. 3. Refer to Accessory Roof Curb Installation Instructions for additional information as required.

B. Slab Mount (Horizontal Units Only)

Provide a level concrete slab that extends a minimum of 6 in. beyond unit cabinet. Install a gravel apron in front of condenser coil air inlet to prevent grass and foliage from obstructing airflow.

NOTE: Horizontal units may be installed on a roof curb if required.

C. Alternate Unit Support

A non-combustible sleeper rail can be used in the unit curb support area. If sleeper rails cannot be used, support the long sides of the unit wi th a minimum of 3 equ ally spaced 4- in. x 4-in. pads on each side.

Pac

INSTALLATION

Plus Series

Sizes 036-072

3 to 6 Tons

10/1/05

II. STEP 2 — FIELD FABRICATE DUCTWORK

On vertical units, secure all ducts to roof curb and building structure. Do not connect ductwork to unit. For hor izon tal applications, field-supplied flanges should be attached to horizontal discharge openings and all ductwork secured to the flanges. Insulate and weatherproof all external ductwork, joints, and roof openings with counter flashing and mastic in accordance with applicable codes.

Ducts passing through a n unc ondit i one d spa ce must be insulated and covered with a vapor barrier.

If a plenum return is used on a vertical unit, the return should be ducted through the roof deck to comply with applicable fire codes.

A minimum clearance is not required around ductwork. Cabinet return-air static pressure (a negative condition) shall not exceed 0.35 in. wg with economizer or 0.45 in. wg without economizer.

These units are designed for a minimum continuous returnair temperature in heating of 50 F (dry bulb), or an intermittent operati on down to 45 F (dry bulb), suc h as when used with a night set-back thermostat.

To operate at lower return-air temperatures, a field-supplied outdoor-air temperature control must be used to initiate both stages of heat when the temperature is below 45 F. Indoor comfort may be compromised when these lower air temperatures are used with insufficient heating temperature rise.

III. STEP 3 — DETERMINE LOCATION OF DRAIN LINE AND EXTERNAL TRAP

The unit’s

/4-in. condensate drain connecti ons are locate d on the bottom and end of the unit. Unit discharge connections do not determine the use of drain conn ections ; either drain connection can be used with vertical or horizontal applications.

When using the standard end drain connection, make sure the plug in the alternate bottom connection is tight before installing the unit.

To use the bottom drain connection for a roof curb installation, relocate the factory-installed plug from the bottom connection to the end connection. The center drain plug looks like a star connection, however it can be removed with a

/2-in. socket drive extens ion. See Fig. 4. The piping for the condensate drain and external trap can be completed after the unit is in place.

All units must have an external trap for condensate drainage. Install a trap at least 4 in. deep and protect against freeze-up. See Fig. 5. If drain line is installed downstream from the external trap, pitch the line away from the unit at 1 in. per 10 ft of run. Do not use a pipe size smaller than the unit connection.

Fig. 1 — Horizontal Conversion Panels

—2—

1′-4″ [406]

D ALT

DRAIN

HOLE

13/4″

[44.5]

GAS POWER CONTROL

/4″

[19] NPT

/2″

[12.7] NPT

[19] NPT

/4″

CONNECTOR

PKG. ACCY.

CRBTMPWR001A01 CRBTMPWR002A01 1

CRBTMPWR003A01

1′-9

[551]

/16″

CRBTMPWR004A01

/4″ [19] NPT

/4″ [31.7]

/4″ [19] NPT

/4″ [31.7]

/2″

[12.7]

/2″

[12.7]

ACCESSORY

PWR

/2″

[12.7]

ROOF CURB

ACCESSORY

CRRFCURB001A01

CRRFCURB002A01

NOTES:

1. Roof curb accessory is shipped disassembled.

2. Insulated panels.

3. Dimensions in [ ] are in millimeters.

4. Roof curb: galvanized steel.

5. Attach ductwork to curb (flanges of duct rest on curb).

6. Service clearance: 4 ft on each side.

A UNIT SIZE

1′-2″

[356]

2′-0″

[610]

581B036-072

7. Direction of airflow.

8. Connector packages CRBTMPWR001A01 and

002A01 are for thru-the-curb type gas. Packages CRBTMPWR003A01 and 004A01 are for thru-thebottom type gas connections.

Fig. 2 — Roof Curb Details

—3—

MAXIMUM ALLOWABLE

DIFFERENCE (in.)

A-B B-C A-C

0.5 1.0 1.0

Fig. 3 — Unit Leveling Tolerances

DRAIN PLUG

NOTE: Drain plug is shown in factory-installed position.

DRAIN PLUGHORIZONTAL

Fig. 4 — Condensate Drain Pan

NOTE: Trap should be deep enough to offset maximum unit static dif-

ference. A 4-in. trap is recommended.

Fig. 5 — Condensate Drain Piping Details

IV. STEP 4 — RIG AND PLACE UNIT

Inspect unit for transportation damage. File any claim with transportation agency. Keep unit upright and do not drop. Spreader bars are not required if top crating is left on unit. Rollers may be used to move unit across a roof. Level by using unit frame as a reference. See Table 1 and Fig. 6 for additional information. Operating weight is shown in Table 1 and Fig. 6.

Lifting holes are provi ded in base rails as shown in Fig. 6 and 7. Refer to rigging instructions on unit .

A. Positioning

Maintain clearan ce around and above un it to provide minimum distance from combustible materials, proper airflow, and service access. See Fig. 7.

Do not install unit in an indoor location. Do not locate unit air inlets near exhaust vents or other sources of contaminated air.

Be sure that unit is installed so that sn ow will not b lock the combustion intake or flue outlet.

Unit may be installed directly on wood flooring or on Class A, B, or C roof-covering material when roof curb is used.

Although unit is weatherproof, guard against water from higher level runoff and overhangs.

Position unit on roof curb so that the following clearances are maintained:

/4 in. clearance betwe en the roof curb and the base rail insi de the fr ont an d rear, 0.0 in. clearance betwe en the roof curb and the base rail inside on the duct end of the unit. This will result i n the distance between the roof cu rb and the base rail inside on the condenser end of the unit being approximately equal to Fig. 2, section C-C.

Locate mechanical draft system flue assembly at least 48 in. from an adjacent building or combustible material. Units having accessory flue discharge deflector require only 18 in. clearance. When unit is located adjacent to public walkways, flue assembly must be at least 7 ft above grade.

Flue gas can deteriorate building materials. Orient unit so that flue gas will not affect building materials.

Adequate combustion and ventilation air space must be provided for proper operation of this equipment. Be sure that installation complies with all local codes and Section 5.3, Air for Combustion and V entilat ion per NFGC (National F uel Gas Code), ANSI (American National Standards Institute) Z223.1latest year and addendum Z223.1A-latest year. In Canada, installation must be in accordance with the CAN1.B149.1 and CAN1.B149.2 installation codes for gas burning appliances.

Flue vent discharge must have a minimum horizontal clearance of 4 ft from electric and gas meters, gas regulators, and gas relief equipment.

After unit is in position, remove shipping materials and rigging skids.

V. STEP 5 — INSTALL FLUE HOOD

Flue hood is shipped screwed to the burner compartment access panel. Remove from shipping location and, using screws provide d , in st all f lue h oo d i n lo cat ion s hown i n Fi g. 7 and 8.

For units being installed in California Air Quality Management Districts which require NOx emi ssions of 40 nanogr ams/ joule or less, a low NOx unit must be installed .

NOTE: Low NOx units are available for 3 to 5 ton units.

VI. STEP 6 — INSTALL GAS PIPING

Unit is equipped for use wi th type of gas shown on nameplate. Refer to local building codes, or in the absence of local codes, to ANSI Z223.1-latest year and addendum Z223.1Alatest year entitled NFGC. In Canada, installation must be in accordance with the CAN1.B149.1 and CAN1.B149.2 installation codes for gas burning appliances.

For natural gas applications, gas pressure at unit gas connection must not be less than 4.0 in. wg or greater than

13.0 in. wg while unit is operating. For liquid propane and high heat applications, the gas pressure must not be less than 5.0 in. wg or greater than 13.0 in. wg at the unit connection.

—4—

NOTES:

1. Place unit on curb as close as possible to the duct end.

2. Dimension in ( ) is in millimeters.

3. Hook rigging shackles through holes in base rail as shown in detail “A.” Holes in base rails are centered around the unit center of gravity. Use wooden top skid when rigging to prevent rigging straps from damaging unit.

4. Weights include base unit without economizer. See Table 1 for unit operating weights and economizer weights.

5. Weights include base unit without the Perfect Humidity™ dehumidification system. See Table 1 for additional unit operating weights with the Perfect Humidity system.

CAUTION: All panels must be in place when rigging.

Fig. 6 — Rigging Details

OPERATING

UNIT 581B

036 530 240 73.69 1872 35.50 902 33.31 847 048 540 245 73.69 1872 35.50 902 33.31 847 060 560 254 73.69 1872 35.50 902 33.31 847 072 635 288 73.69 1872 35.50 902 33.31 847

WEIGHT

lb kg in. mm in. mm in. mm

“A” “B” “C”

Size gas supply piping for 0.5-in. wg maximum pressure drop. Do not use supply pipe smaller than unit gas connection.

Support gas piping as shown in the table in Fig. 9. For exam-

ple, a

/4-in. gas pipe must have one field-fabricated support beam every 8 ft. Ther ef or e, an 18-ft long gas pipe would h a v e a minimum of 3 support beams. See Fig. 9 for typical pipe guide and locations of external manual gas shutoff valve.

NOTE: If accessory thru-the-bottom connections and roof curb are used, refer to the Thru-the-Bottom Accessory

Installation Instructions for information on power wiring and gas connection piping. Power wiring, control wiring and gas connection piping can be routed through field-drilled holes in the basepan, which is specifically designed and dimpled for drilling the accessory connection holes.

CAUTION: When connecting the gas line to the unit gas valve, the installer MUST use a backup wrench to prevent damage to the valve.

—5—

Table 1 — Physical Data — 581B036-072

UNIT SIZE 581B 036 048 060 072 NOMINAL CAPACITY 3456 OPERATING WEIGHT (lb)

Unit 530 540 560 635 EconoMi$er IV 50 50 50 50 Perfect Humidity™ Dehumidification System 15 23 23 29 Roof Curb 115 115 115 115

COMPRESSOR Scroll

Quantity 1111 Oil (oz) 42 53 50 60

REFRIGERANT TYPE R-22

Operating Charge (lb-oz) Standard Unit 5-8 10-2 10-0 12-8 Unit With Perfect Humidity Dehumidification System 9-0 15-8 17-0 21-0

CONDENSER FAN Propeller

Quantity...Diameter (in.) 1...22 1...22 1...22 1...22 Nominal Cfm 3500 3500 4100 4100 Motor Hp...Rpm Watts Input (Total) 180 180 320 320

CONDENSER COIL Enhanced Copper Tubes, Aluminum Lanced Fins

Rows...Fins/in. 1...17 2...17 2...17 2...17 Total Face Area (sq ft) 14.6 16.5 16.5 16.5

EVAPORATOR COIL Enhanced Copper Tubes, Aluminum Double-Wavy Fins, Acutrol™ Metering Device

Standard Unit

Rows...Fins/in. 2...15 2...15 4...15 4...15 Total Face Area (sq ft) 5.5 5.5 5.5 5.5

Unit with Perfect Humidity Dehumidification System

Rows...Fins/in. 1...17 2...17 2...17 2...17 Total Face Area (sq ft) 3.9 3.9 3.9 5.2

EVAPORATOR FAN Centrifugal Type, Belt Drive

Quantity...Size (in.) 1...10 x 10 1...10 x 10 1...10 x 10 1...10 x 10 Nominal Cfm 1200 1600 2000 2400 Maximum Continuous Bhp Std 1.20 1.20 1.30/2.40* 2.40

Motor Frame Size Std 48 48 48/56* 56

Fan Rpm Range Std 680-1044 770-1185 1035-1460 1119-1585

Motor Bearing Type Ball Ball Ball Ball Maximum Fan Rpm 2100 2100 2100 2100 Motor Pulley Pitch Diameter A/B (in.) Std 1.9/2.9 1.9/2.0 2.4/3.4 2.4/3.4

Nominal Motor Shaft Diameter (in.) Std

Fan Pulley Pitch Diameter (in.) Std 4.5 4.0 4.0 4.0

Belt — Type...Length (in.) Std 1...A...36 1...A...36 1....4...40 1...A...38

Pulley Center Line Distance (in.) 10.0-12.4 10.0-12.4 14.7-15.5 14.7-15.5 Speed Change per Full Turn of

Movable Pulley Flange (rpm)

Movable Pulley Maximum Full

Turns from Closed Position

Factory Setting — Full Turns Open Std 3333

Factory Speed Setting (rpm) Std 826 936 1248 1305

Fan Shaft Diameter at Pulley (in.)

Hi-Static 2.40 2.40 2.90 2.90

Hi-Static 56 56 56 56

Hi-Static 1075-1455 1075-1455 1300-1685 1300-1685

Hi-Static 2.8/3.8 2.8/3.8 3.4/4.4 3.4/3.4

Hi-Static

Hi-Static 4.5 4.0 4.5 4.5

Hi-Static 1...A...39 1...A...39 1...A...40 1...A...40

Std 65 70 75 95

Hi-Static 65 65 60 60

Std 5565

Hi-Static 6655

Hi-Static 3

Hi-Static 1233 1233 1396 1396

LEGEND Bhp — Brake Horsepower

*Single phase/three phase.

†Indicates automatic reset.

**60,000 and 72,000 Btuh heat input units have 2 burners. 90,000 and

120,000 Btuh heat input units have 3 burners. 115,000 Btuh heat input units and 150,000 Btuh Heat input units have 3 burners.

/4...825

31/

units.

2 8

††An LP kit is available as an accessory. If an LP kit is used with low NO

one low NOx baffle must be removed and the units will no longer be classified as low NO

||California compliant three-phase models.

***California SCAQMD compliant low NO

are controlled to 40 nanograms per joule or less.

/4...1100

31/

models have combustion products that

/4...1100

31/

units,

—6—

Table 1 — Physical Data — 581B036-072 (cont)

UNIT SIZE 581B 036 048 060 072 FURNACE SECTION

Rollout Switch Cutout Temp (F)† 195 195 195 195

Burner Orifice Diameter (in. ...drill size)**

Natural Gas — Std 071/072 .113...33 .113...33 .113...33 .113...33

Liquid Propane — Alt††

Thermostat Heat Anticipator Setting (amps) 208/230/460 v

First Stage .14 .14 .14 .14 Second Stage .14 .14 .14 .14

Gas Input (Btuh)

First Stage/Second Stage (3-phase units) 072 50,000/ 72,000 50,000/ 72,000 50,000/ 72,000 50,000/ 72,000

Efficiency (Steady State) (%)

Temperature Rise Range

Manifold Pressure (in. wg)

Natural Gas — Std 3.5 3.5 3.5 3.5

Liquid Propane — Alt†† 3.5 3.5 3.5 3.5 Maximum Static Pressure (in. wg) 1.0 1.0 1.0 1.0 Field Gas Connection Size (in.)

HIGH-PRESSURE SWITCH (psig)

Standard Compressor Internal Relief Cutout Reset (Auto.)

LOSS-OF-CHARGE SWITCH/LOW-PRESSURE

SWITCH (Liquid LIne) (psig) Cutout Reset (Auto.)

FREEZE PROTECTION THERMOSTAT

Opens (F) Closes (F)

OUTDOOR-AIR INLET SCREENS

Quantity...Size (in.)

RETURN-AIR FILTERS Throwaway

Quantity...Size (in.) 2...16 x 25 x 2

LEGEND

Brake Horsepower

Bhp —

*Single phase/three phase.

†Indicates automatic reset.

**60,000 and 72,000 Btuh heat input units have 2 burners. 90,000 and

120,000 Btuh heat input units have 3 burners. 115,000 Btuh heat input units and 150,000 Btuh Heat input units have 3 burners.

114/115 .113...33 .113...33 .113...33 .113...33 149/150 — .129...30 .129...30 .129...30

060N .102...38 .102...38 .102...38 — 090N .102...38 .102...38 .102...38 — 120N — .116...32 .116...32 —

071/072 .089...43 .089...43 .089...43 .089...43 114/115 .089...43 .089...43 .089...43 .089...43 149/150 — .102...38 .102...38 .102...38

060N .082...45 .082...45 .082...45 — 090N .082...45 .082...45 .082...45 — 120N — .094...42 .094...42 —

115 82,000/115,000 82,000/115,000 82,000/115,000 82,000/115,000 150 — 120,000/150,000 120,000/150,000 120,000/150,000

071II —/ 72,000 —/ 72,000 —/ 72,000 — 114II —/115,000 —/115,000 —/115,000 — 149II — —/150,000 —/150,000 —

060N*** —/ 60,000 —/ 60,000 —/ 60,000 — 090N*** —/ 90,000 —/ 90,000 —/ 90,000 — 120N*** — —/120,000 —/120,000 —

072 82.8 82.8 82.8 82 115 80 81 81 81 150 — 80.4 80.4 80

071 82 82 82 — 114 80 81 81 — 149 —8080—

060N 80.2 80.2 80.2 — 090N 81 81 81 — 120N — 80.7 80.7 —

072 25-55 25-55 25-55 25-55 115 55-85 35-65 35-65 35-65 150 — 50-80 50-80 50-80

071 25-55 25-55 25-55 — 114 55-85 35-65 35-65 — 149 — 50-80 50-80 —

060N 20-50 20-50 20-50 — 090N 30-60 30-60 30-60 — 120N — 40-70 40-70 —

450 ± 50

428 320

7 ± 3

22 ± 5

30 ± 5 45 ± 5

Cleanable

1...20 x 24 x 1

4...16 x 16 x 2

††An LP kit is available as an accessory. If an LP kit is used with low NO

one low NO as low NO

||California compliant three-phase models.

***California SCAQMD compliant low NOx models have combustion products that

are controlled to 40 nanograms per joule or less.

baffle must be removed and the units will no longer be classified

units.

units,

—7—

—8—

Fig. 7 — Base Unit Dimensions — 581B036-072

Fig. 8 — Flue Hood Details

LEGEND NFGC — National Fuel Gas Code

*Field supplied.

NOTE: Follow all local codes.

STEEL PIPE

NOMINAL DIAMETER

(in.)

or 1

or larger

SPACING OF SUPPORTS

X DIMENSION

(ft)

6 8

Fig. 9 — Gas Piping Guide (With Accessory

Thru-the-Curb Service Connections)

VII. STEP 7 — MAKE ELECTRICAL CONNECTIONS

WARNING: Unit cabinet must have an uninter-

rupted, unbroken electrical ground to minimize the possibility of personal injury if an electrical fault should occur. This ground may consist of electrical wire connected to unit ground lug in control compartment, or conduit approved for electrical ground when installed in accordance with NEC (National Electrical Code), ANSI/NFPA (National Fire Protection Association), latest edition, and local electrical codes. Do not use gas piping as an electrical ground. Failure to follow this warning could result in the installer being liable for personal injury of other s.

A. Field Power Supply

All units except 208/230-v units are factory wired for the voltage shown on the nam eplate. If the 208/230-v unit is to be connected to a 208-v power supply, the transformer must be rewired by moving the blac k wire fro m the 230 -v terminal on the transforme r and connecting it to the 200-v terminal on the transformer.

Refer to unit label diagram for additional information. Pigtails are provided for field service. Use factory-supplied splices or UL (Underwriters’ Laborato ries) approved copper connector.

When installing units, provide a disconnect per NEC. All field wiring must comply with NEC and local require-

ments. In Canada, electrical connections must be in accordance with CSA (Canadian Standards Association) C22.1 Canadian Electrical Code Part One.

Install conduit through side panel openings indicated in Fig. 7. Route power lines through connector to terminal connections as shown in Fig. 10.

On 3-phase units, voltages between phase s must be balanced within 2% and the current within 10%. Use the formula shown in Note 3 under Tables 2A-2D to determine the percentage of voltage imbalance. Operation on improper line voltage or excessive phase imbalance constitutes abuse and may cause damage to electrical components. Such operation would invalidate any applicable Bryant warranty.

NOTE: If thru-the-bottom accessory connections are used, refer to the thru-the-bottom accessory installation instructions for power wiring. Refer to Fig. 7 for location to drill holes in basepan.

B. Field Control Wiring

Install a Bryant-approved accessory thermostat assembly according to installation instructions included with the accessory. Locate thermostat assembly on a solid wall in the conditioned space to sense average temperature in accordance with thermostat installation instructions.

Route thermostat cable or equivalent single leads of colored wire from thermostat subbase terminals to low-voltage connections on unit (shown in Fig. 11) as described in Steps 1-4 below.

1. If mounted on a ro of cu rb an d el ec tr ic al powe r is to b e run through the basepan, an accessory thru-the-bottom connection kit is required. This is available through the local Bryant distributor. This kit is required to ensure a relia ble water-tight connection.

2. If unit is mounte d on roof curb and accessory thruthe-bottom connections are used, route wire through connection plate.

3. Pass control wires thro ugh th e hole pro vided o n unit (see connection D, Connection Sizes table, Fig. 7).

4. Feed wires through the raceway built into the corner post to the 24-v barrier located on the left side of the control box. See Fig. 12. The raceway provides the UL-required clearance between high- and low-voltage wiring.

5. Connect thermostat wires to s crew terminals of lowvoltage connection board (see Fig. 11).

NOTE: For wire runs up to 50 ft, use no. 18 AWG (American Wire Gage) insulated wire (35 C minimum). For 51 to 75 ft, use no. 16 AWG insulated wire (35 C minimum). For over 75 ft, use no. 14 AWG insulated wire (35 C minimum).

NOTE: All wire larger than no. 18 AWG cannot be directly connected to the thermostat and will require a junction box and splice at the thermostat.

C. Heat Anticipator Settings

Set heat anticipator settings at 0.14 amp for first stage and

0.14 amp for second-stage heating, when available.

—9—

Fig. 10 — Power Wiring Connections

BRYANT ELECTRONIC THERMOSTAT

LEGEND

C—Contactor

C—Contactor COMP — Compressors

COMPS — Compressors EQUIP — Equipment

EQUIP — Equipment GND — Ground

GND — Ground IFC — Indoor (Evaporator)

IFC — Indoor (Evaporator)

NEC — National Electrical Code

NEC — National Electrical Code TB — Terminal Block

TB — Terminal Block

Fan Contactor

COOL STAGE 1

FAN

HEAT STAGE 1

COOL STAGE 2

HEAT STAGE 2

24 VAC HOT

24 VAC COM

N/A

OUTDOOR AIR

SENSOR

THERMOSTAT DIPSWITCH SETTINGS ON

OFF

Y1/W2

W/W1

Y/Y2

O/W2

IPD/X

WIRE CONNECTIONS TO LOW-VOLTAGE SECTION

LEGEND

Field Wiring

NOTE: Underlined letter indicates active thermostat output when configured for A/C operation.

Fig. 11 — Low-Voltage Connections With or

Without Economizer

RACEWAY LOW VOLTAGE

HOLE IN END PANEL (HIDDEN)

CONNECTIONS

INTEGRATED GAS UNIT CONTROLLER (IGC)

Fig. 12 — Field Control Wiring Raceway

—10—

Table 2A — Electrical Data — Standard Motor Units Without Electrical Convenience Outlet

UNIT 581B

036

(3 Tons)

048

(4 Tons)

060

(5 Tons)

072

(6 Tons)

NOMINAL VOLTAGE

(V-Ph-Hz)

208/230-1-60 187 254 208/230-3-60 187 254 10.3 77.0 0.7 4.9 .60 18.5/18.5 25/25 18/18 90/90

460-3-60 414 508 5.1 39.0 0.4 2.2 .30 9.0 20 9 46

575-3-60 518 632 4.2 31.0 0.4 2.2 .30 7.3 20 7 37 208/230-1-60 187 254 208/230-3-60 187 254 13.5 93.0 0.7 4.9 .60 22.5/22.5 30/30 22/22 106/106

460-3-60 414 508 6.4 46.5 0.4 2.2 .30 10.6 20 10 54

575-3-60 518 632 6.4 40.0 0.4 2.2 .30 10.1 20 10 46 208/230-1-60 187 254 208/230-3-60 187 254 17.3 123.0 1.5 5.8 .60 28.9/28.9 35/35 28/28 168/168

460-3-60 414 508 9.0 62.0 0.8 2.6 .30 14.7 20 14 84

575-3-60 518 632 7.1 50.0 0.8 2.6 .30 11.6 20 12 68 208/230-3-60 187 254

460-3-60 414 508 9.6 75.0 0.6 2.6 .30 15.2 20 15 97

575-3-60 518 632 7.7 56.0 0.6 2.6 .30 12.2 20 12 74

VOLTAGE

RANGE

Min Max Qty RLA LRA FLA FLA FLA MCA MOCP** FLA LRA

COMPRESSOR

(each)

16.0 88.0 0.7 4.9 .60 25.6/25.6 30/30 25/25 101/101

23.7 126.0 0.7 4.9 .60 35.2/35.2 45/45 34/34 139/139

28.8 169.0 1.5 8.8 .60 46.3/46.3 60/60 45/45 216/216

20.5 156.0 1.4 5.8 .60 32.8/32.8 40/40 32/32 200/200

Table 2B — Electrical Data — Standard Motor Units With Electrical Convenience Outlet

UNIT 581B

036

(3 Tons)

048

(4 Tons)

060

(5 Tons)

072

(6 Tons)

FLA — Full Load Amps HACR — Heating, Air Conditioning and

IFM — Indoor (Evaporator) Fan Motor LRA — Locked Rotor Amps MCA — Minimum Circuit Amps MOCP — Maximum Overcurrent Protection NEC — National Electrical Code OFM — Outdoor (Condenser) Fan Motor RLA — Rated Load Amps UL — Underwriters’ Laboratories

*The values listed in this table do not include power exhaust. See table at right for

power exhaust requirements.

†Used to determine minimum disconnect per NEC.

**Fuse or HACR circuit breaker.

NOTES:

1. In compliance with NEC requirements for multimotor and combination load equipment (refer to NEC Articles 430 and 440), the overcurrent protective device for the unit shall be fuse or HACR breaker. The UL, Canada units may be fuse or circuit breaker.

2. Electrical data based on 95 F ambient outdoor-air temperature ± 10% voltage.

3. Unbalanced 3-Phase Supply Voltage

Never operate a motor where phase imbalance in supply voltage is greater than 2%. Use the following formula to determine the percent voltage imbalance.

% Voltage Imbalance

= 100 x

Example: Supply voltage is 460-3-60.

Determine maximum deviation from average voltage.

NOMINAL VOLTAGE

(V-Ph-Hz)

208/230-1-60 187 254 208/230-3-60 187 254 10.3 77.0 0.7 4.9 .60 24.5/24.5 30/30 24/24 95/95

460-3-60 414 508 5.1 39.0 0.4 2.2 .30 11.7 20 11 48

575-3-60 518 632 4.2 31.0 0.4 2.2 .30 9.5 20 9 38 208/230-1-60 187 254 208/230-3-60 187 254 13.5 93.0 0.7 4.9 .60 28.5/28.5 35/35 27/27 111/111

460-3-60 414 508 6.4 46.5 0.4 2.2 .30 13.3 20 13 56

575-3-60 518 632 6.4 40.0 0.4 2.2 .30 12.2 20 12 47 208/230-1-60 187 254 208/230-3-60 187 254 17.3 123.0 1.5 5.8 .60 34.9/34.9 40/40 34/34 173/173

460-3-60 414 508 9.0 62.0 0.8 2.6 .30 17.4 20 17 87

575-3-60 518 632 7.1 50.0 0.8 2.6 .30 13.8 20 13 70 208/230-3-60 187 254

460-3-60 414 508 9.6 75.0 0.6 2.6 .30 17.9 20 17 99

575-3-60 518 632 7.7 56.0 0.6 2.6 .30 14.3 20 14 75

LEGEND

Refrigeration

max voltage deviation from average voltage

AB = 452 v

BC = 464 v

AC = 455 v

Average Voltage =

VOLTAGE

RANGE

Min Max Qty RLA LRA FLA FLA FLA MCA MOCP** FLA LRA

average voltage

452 + 464 + 455

1371

= 457

COMPRESSOR

(each)

16.0 88.0 0.7 4.9 .60 31.6/31.6 35/35 30/30 106/106

23.7 126.0 0.7 4.9 .60 41.2/41.2 50/50 39/39 144/144

28.8 169.0 1.5 8.8 .60 52.3/52.3 60/60 50/50 221/221

20.5 156.0 1.4 5.8 .60 38.8/38.8 45/45 37/37 205/205

OFM

(each)

OFM

(each)

COMBUSTION

IFM

FAN MOTOR

COMBUSTION

IFM

FAN MOTOR

(AB) 457 – 452 = 5 v (BC) 464 – 457 = 7 v

(AC) 457 – 455 = 2 v Maximum deviation is 7 v. Determine percent of voltage imbalance.

% Voltage Imbalance = 100 x

This amount of phase imbalance is satisfactory as it is below the maximum allowable 2%.

IMPORTANT: If the supply voltage phase imbalance is more than 2%, contact your local electric utility company immediately.

= 1.53%

POWER

SUPPLY*

POWER SUPPLY

WITH OUTLET*

7 457

MINIMUM UNIT

DISCONNECT SIZE†

MINIMUM UNIT

DISCONNECT SIZE†

POWER EXHAUST ELECTRICAL DATA

POWER EXHAUST

PART NO.

CRPWREXH021A01 N/A 0.9 N/A 15 CRPWREXH022A01 3.3 N/A 1.32 15 CRPWREXH023A01 N/A 1.8 N/A 15 CRPWREXH028A01 1.7 N/A 0.68 15 CRPWREXH029A01 N/A 1.0 N/A 15 CRPWREXH030A01 1.6 N/A 0.64 15

N/A — Not available

NOTE: If a single power source is to be used, size wire to include power exhaust MCA and MOCP.

Check MCA and MOCP when power exhaust is powered through the unit. Determine the new MCA including the power exhaust using the following formula:

MCA New = MCA unit only + MCA of Power Exhaust For example, using a 581B072 unit with MCA = 32.8 and MOCP = 40, with

CRPWREXH030A01 power exhaust. MCA New = 32.8 amps + 1.6 amps = 34.4 amps If the new MCA does not exceed the published MOCP, then MOCP would not

change. The MOCP in this example is 40 amps and the MCA New is below 40; therefore the MOCP is acceptable. If “MCA New” is larger than the published MOCP, raise the MOCP to the next larger size. For separate power, the MOCP for the power exhaust will be 15 amps per NEC.

MCA

(230 v)

MCA

(460 v)

MCA

(575 v)

MOCP

(for separate

power source)

—11—

Table 2C — Electrical Data — High-Static Motor Units Without Electrical Convenience Outlet

UNIT 581B

036

048

060

072

NOMINAL VO LTAG E

(V-Ph-Hz)

208/230-3-60 187 254

460-3-60 414 508 5.1 39.0 0.4 2.6 0.3 9.4 20 9 60 575-3-60 518 632 4.2 31.0 0.4 2.6 0.3 7.7 20 8 48

208/230-3-60 187 254

460-3-60 414 508 6.4 46.5 0.4 2.6 0.3 11.0 20 11 68 575-3-60 518 632 6.4 40.0 0.4 2.6 0.3 10.4 20 10 57

208/230-3-60 187 254

460-3-60 414 508 9.0 62.0 0.8 3.4 0.3 15.5 20 15 94 575-3-60 518 632 7.1 50.0 0.8 3.4 0.3 12.2 20 12 76

208/230-3-60 187 254

460-3-60 414 508 9.6 75.0 0.6 3.4 0.3 16 20 16 107 575-3-60 518 632 7.7 56.0 0.6 3.4 0.3 12.8 20 13 81

VOLTAGE

RANGE

Min Max Qty RLA LRA FLA FLA RLA MCA MOCP** FLA LRA

COMPRESSOR

(each)

10.3 77.0 0.7 5.8 0.6 19.4 25 19 120

13.5 93.0 0.7 5.8 0.6 23.4 30 23 136

17.3 123.0 1.5 7.5 0.6 30.6 35 30 187

20.5 156.0 1.4 7.5 0.6 34.5 40 34 219

Table 2D — Electrical Data — High-Static Motor Units With Electrical Convenience Outlet

UNIT 581B

036

048

060

072

FLA — Full Load Amps HACR — Heating, Air Conditioning and

*The values listed in this table do not include power exhaust. See table at right for

power exhaust requirements.

†Used to determine minimum disconnect per NEC.

**Fuse or HACR circuit breaker.

NOTES:

1. In compliance with NEC requirements for multimotor and combination load

2. Electrical data based on 95 F ambient outdoor-air temperature ± 10% voltage.

3. Unbalanced 3-Phase Supply Voltage

NOMINAL VOLTAGE

(V-Ph-Hz)

208/230-3-60 187 254

460-3-60 414 508 5.1 39.0 0.4 2.6 0.3 12.1 20 12 63 575-3-60 518 632 4.2 31.0 0.4 2.6 0.3 9.8 20 10 50

208/230-3-60 187 254

460-3-60 414 508 6.4 46.5 0.4 2.6 0.3 13.7 20 13 70 575-3-60 518 632 6.4 40.0 0.4 2.6 0.3 12.6 20 12 59

208/230-3-60 187 254

460-3-60 414 508 9.0 62.0 0.8 3.4 0.3 18.2 20 18 96 575-3-60 518 632 7.1 50.0 0.8 3.4 0.3 14.4 20 14 77

208/230-3-60 187 254

460-3-60 414 508 9.6 75.0 0.6 3.4 0.3 18.7 25 18 109 575-3-60 518 632 7.7 56.0 0.6 3.4 0.3 15.0 20 15 83

LEGEND

Refrigeration

equipment (refer to NEC Articles 430 and 440), the overcurrent protective device for the unit shall be fuse or HACR breaker. The UL, Canada units may be fuse or circuit breaker.

Never operate a motor where phase imbalance in supply voltage is greater than 2%. Use the following formula to determine the percent voltage imbalance.

% Voltage Imbalance

= 100 x

Example: Supply voltage is 460-3-60.

Determine maximum deviation from average voltage.

max voltage deviation from average voltage

VOLTAGE

RANGE

Min Max Qty RLA LRA FLA FLA RLA MCA MOCP** FLA LRA

average voltage

AB = 452 v BC = 464 v AC = 455 v

Average Voltage =

1371

= 457

COMPRESSOR

10.3 77.0 0.7 5.8 0.6 25.4 30 25 124

13.5 93.0 0.7 5.8 0.6 29.4 35 29 140

17.3 123.0 1.5 7.5 0.6 36.6 40 36 192

20.5 156.0 1.4 7.5 0.6 40.5 45 39 224

452 + 464 + 455

(each)

OFM

(each)

OFM

(each)

IFM

COMBUSTION

FAN MOTOR

COMBUSTION

FAN MOTOR

(AB) 457 – 452 = 5 v (BC) 464 – 457 = 7 v

(AC) 457 – 455 = 2 v Maximum deviation is 7 v. Determine percent of voltage imbalance.

% Voltage Imbalance = 100 x

This amount of phase imbalance is satisfactory as it is below the maximum allowable 2%.

IMPORTANT: If the supply voltage phase imbalance is more than 2%, contact your local electric utility company immediately.

= 1.53%

7 457

POWER

SUPPLY*

POWER

SUPPLY*

MINIMUM UNIT

DISCONNECT

MINIMUM UNIT

DISCONNECT

POWER EXHAUST ELECTRICAL DATA

POWER EXHAUST

PART NO.

CRPWREXH021A01 N/A 0.9 N/A 15 CRPWREXH022A01 3.3 N/A 1.32 15 CRPWREXH023A01 N/A 1.8 N/A 15 CRPWREXH028A01 1.7 N/A 0.68 15 CRPWREXH029A01 N/A 1.0 N/A 15 CRPWREXH030A01 1.6 N/A 0.64 15

N/A — Not available

NOTE: If a single power source is to be used, size wire to include power exhaust MCA and MOCP.

Check MCA and MOCP when power exhaust is powered through the unit. Determine the new MCA including the power exhaust using the following formula:

MCA New = MCA unit only + MCA of Power Exhaust For example, using a 581B072 unit with MCA = 32.8 and MOCP = 40, with

CRPWREXH030A01 power exhaust. MCA New = 32.8 amps + 1.6 amps = 34.4 amps If the new MCA does not exceed the published MOCP, then MOCP would not

MCA

(230 v)

MCA

(460 v)

MCA

(575 v)

SIZE†

MOCP

(for separate

power source)

—12—

VIII. STEP 8 — ADJUST FACTORY-INSTALLED OPTIONS

A. Disconnect Switch

The optional disconnect switch is non-fused. The switch has the capability of bei ng locked in place for safety purposes.

B. Perfect Humidity™ Dehumidification System

Perfect Humidity system operation can be controlled by field installation of a Bryant-approved humidistat device (Fig. 13), or light commercial Thermidistat™ device (Fig. 14). To install the humidistat device:

1. Route humidistat cable through hole provided in unit corner post.

2. Feed wires through the raceway built into th e corner post to the 24-v barrier located on the l eft side of the control box. See Fig. 12. The raceway provides the UL-required clearance betw ee n high -volta ge and l owvoltage wiring.

3. Use a wire nut to connect humidistat cable into lo wvoltage wiring as shown in Fig. 15.

To install Thermidistat device:

1. Route Thermidistat cable through hole provided in unit corner post.

2. Feed the wires through the raceway built into the corner post to the 24-v barrier located on the left side of the control box. See Fig. 12. The raceway provides the UL-required clearance between high and low voltage wiring.

3. A field-supplied relay must be installed between the Thermidistat device and the Perfect Humidity circuit (recommended relay: HN612KK324). See Fig. 16. The relay coil is connected between the DEHUM output and C (common) of the unit. The relay controls the Perfect Humidity solenoid valve and must be wired between the Perfect Humidity fuse and the low-pressure switch. Refer to the installation instructions included with the Bryant Light Commercial Thermidistat device for more information.

% RELATIVE HUMIDITY

Fig. 13 — Accessory Field-Installed Humidistat Device

Fig. 14 — Light Commercial Thermidistat Device

C—Contactor (Compressor) CB — Circuit Breaker CR — Cooling Relay DHR — Dehumidify Relay DSV — Discharge Solenoid Valve HU — Humidistat

LPS —

LSV — Liquid Line Solenoid Valve

Low Pressure Switch

LEGEND

LTLO —

TRAN — Transformer

Low Temperature Lockout

Terminal (Unmarked)

Splice

Factory Wiring

Accessory or Optional Wiring

Fig. 15 — Typical Perfect Humidity Dehumidification System

Humidistat Wiring (208/230-v Unit Shown)

—13—

LCT

C Y1 Y2

G W1 W2

DEHUM

CB — Circuit Breaker LCT — Light Commercial Thermidistat™ Device LLSV — Liquid Line Solenoid Valve LTLO — Low Temperature Lockout

T STAT WIRES

LEGEND

Fig. 16 — Typical Rooftop Unit with Perfect Humidity™ Dehumidification System with Thermidistat Device

C. Convenience Outlet

An optional convenience outlet provides power for rooftop use. For maintenance personnel safety, the convenience outlet power is off when the unit disconnect is off. Adjacent unit outlets may be used f or service tools. An optional “Ho t Outlet” is available from the factory as a special order item.

D. Manual Outdoor-Air Damper

The outdoor-air hood and screen are attached to the basepan at the bottom of the unit for shipping.

Assembly:

1. Determine quantity of ventilation required for building. Record amount for use in Step 8.

2. Remove outdoor-air opening panel. Save panels and screws. See Fig. 17.

3. Remove evaporator coil access panel. Separate hood and screen from basepan by removing the 4 scre ws securing them. Save all screws.

4. Replace evaporator coil access panel.

5. Place hood on front of outdoor-air opening panel. See Fig. 18 for hood details. Secure top of hood with the 4 screws removed in Step 3. See Fig. 19.

6. Remove and save 6 screws (3 on each side) from sides of the manual outdo or-air damper.

7. Align screw holes on hood with screw holes on side of manual outdoor-air damper. See Fig. 18 and 19. Secure hood with 6 screws from Step 6.

8. Adjust minimum position setting of the damper blade by adjusting the manual outdoor-air adjustment screws on the fron t of the damper bl ade. See Fig. 17. Slide blade vertically until it is in the appropriate position determined by Fig. 20. Tighten screws.

9. Remove and save screws currently on sides of hood. Insert screens. Secure screens to hood using the screws. See Fig. 19.

ROOF TOP UNIT

OUTDOOR AIR OPENING PANEL

3 SCREWS (SIDE)

Fig. 17 — Damper Panel with Manual

R C

PINK

PERFECT HUMIDITY SYSTEM

3.2 AMPS

LTLO

RED

PINK

Outdoor-Air Damper Installed

24 V

FROM PERFECT HUMIDITY SYSTEM LLSV

—14—

Fig. 18 — Outdoor-Air Hood Details

WIRING HARNESS

ACTUATOR

ECONOMI$ER IV CONTROLLER

OUTSIDE AIR TEMPERATURE SENSOR

LOW AMBIENT SENSOR

Fig. 19 — Optional Manual Outdoor-Air Damper

with Hood Attached

Fig. 20 — Outdoor-Air Damper Position Setting

E. Optional EconoMi$er IV

See Fig. 21 for EconoMi$er IV component locations. NOTE: These instructions are for installing the optional

EconoMi$er IV only. Refer to the accessory EconoMi$er IV installation instructions when field installing an EconoMi$er IV accessory.

1. To remove the existing unit filter access panel, raise the panel and swing the bottom outward. The panel is now disengaged from the track and can be removed. See Fig. 22.

2. The box with the economizer hood components is shipped in the compartment behind the economizer. The EconoMi$er IV controller is mounted on top of the EconoMi$er I V in the position shown in Fig. 21. To remove the component box from its shipping position, remove the scr ew holding the ho od box bracket to the top of the economizer. Slide the hood box out of the unit. See Fig. 23.

Fig. 21 — EconoMi$er IV Component Locations

FILTER ACCESS PANEL

COMPRESSOR ACCESS PANEL

OUTDOOR-AIR OPENING AND INDOOR COIL ACCESS PANEL

Fig. 22 — Typical Access Panel Locations

HOOD BOX BRACKET

Fig. 23 — Hood Box Removal

—15—

IMPORTANT: If the power exhaust accessory is to be installed on the unit, the hood shipped with the unit will not be used and must be discarded. Save the aluminum filter

for use in the power exhaust hood assembly.

3. The indoor coil access panel will be used as the top of the hood. Remove the screws along the sides an d bottom of the indoor coil access panel. See Fig. 24.

4. Swing out indoor coil access panel and insert the hood sides under the panel (hood top). Use the screws provided to attach the hood sides to the hood top. Use screws provided to attach the hoo d sides to the unit. See Fig. 25.

5. Remove the shipping tape holding the economizer barometric relief damper in place.

6. Insert the ho od divider between the hood side s. See Fig. 25 and 26. Secure hood divider with 2 screws on each hood side. The hood di vider is also used as the bottom filter rack for the aluminum filter.

BAROMETRIC RELIEF

17 1/4”

DIVIDER

OUTSIDE AIR

CLEANABLE ALUMINUM FILTER

FILTER

Fig. 26 — Filter Installation

HOOD

FILTER CLIP

SIDE PAN EL

CAULK

INDOOR COIL ACCESS PANEL

HERE

Fig. 24 — Indoor Coil Access Panel Relocation

TOP PANEL

INDOOR COIL ACCESS PANEL

LEFT HOOD SIDE

19 1/16”

HOOD DIVIDER

SCREW

33 3/8”

Fig. 25 — Outdoor-Air Hood Construction

TOP SIDE PANEL

INDOOR COIL ACCESS PAN EL

7. Open the filter clips which are located underneath the hood top. Insert the aluminum filter into the bottom filter rack (hood divider). Push the filter into position past the ope n fil ter cli ps . Clos e th e filt er c lip s to lock the filter into place. See Fig. 26.

8. Caulk the ends of the joint between the unit top panel and the hood top. See Fig. 24.

9. Replace the filter access panel.

10. Install all EconoMi$er IV accessories. EconoMi$er IV wiring is shown in Fig. 27.

Barometric flow capacity is shown in Fig. 28. Outdoor air leakage is shown in Fig. 29. Return air pressure drop is shown in Fig. 30.

F. EconoMi$er IV Standard Sensors

Outdoor Air Temperature (OAT) Sensor The outdoor air temperature sensor (HH57AC074) is a 10 to

20 mA device used to me asure the outdoor-air tempera ture. The outdoor-air tempera ture is used t o determine whe n the EconoMi$er IV can be used for free cooling. The sensor is factory-installed on the EconoMi$er IV in the outdoor airstream. See Fig. 21. The ope rating range of temperatu re measurement is 40 to 100 F.

Supply Air Temperature (SAT) Sensor The supply air temperature sensor is a 3 K thermistor

located at the inlet of the indo or fan. See Fig. 31. This sensor is factory installed. The operating range of temperature measurement is 0° to 158 F. See Table 3 for sensor temperature/resistance values.

The temperature sensor looks like an eyelet terminal with wires running to it. The sensor is located in the “crimp end” and is sealed from moisture.

Outdoor Air Lockout Sensor The EconoMi$er IV is equipped with an ambient t empera-

ture lockout switch located in the outdoor airstream which is used to lockout the compressors below a 42 F ambient temperature. See Fig. 21.

—16—

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