B24 SERVICE UNIT INFORMATION B24 SERIES ADD-ON BLOWER ECB24 SERIES ELECTRIC HEAT

Transcription

1 SERVICE UNIT INFORMATION Corp L2 B24 Litho U.S.A. The B24 blower units are designed for multi-position installation with add-on C22FC/CR22/CH22 or C24FC/ CR24/CH24 series coil sections. The B24 may also be used as stand-alone blower or electric furnace when cooling is not required. Four models are available with blowers ranging in size from 2 through 5 tons nominal capacity. Optional electric heat sections are available in sizes ranging from 2.5 through 30 kw. B24 series blower units are equipped with a solid state blower control board located in the control box. The board is equipped with an on-board diagnostic system. A LED is provided for easy troubleshooting. The solid state control board is equipped with all of the relays and controls to operate the system. Jumper selectors on the board control blower speed operation and allow for continuous blower operation. The control board has a built in low voltage terminal strip for thermostat and outdoor unit low voltage wiring connections. Plug in control connections are provided for the addition of optional electric heat. The control board is equipped with two fuses: the electronics are protected by an automotive spade type fuse and the blower is protected by an AGC type glass fuse. A45 BLOWER CONTROL BOARD B24 SERIES ADD-ON BLOWER ECB24 SERIES ELECTRIC HEAT B24 BLOWER (shown in upflow position) (575V unit shown) C22 or C24 COIL (upflow shown) Optional electric heat (ECB24) is quickly field installed with a simple plug-in control connection. Helix wound nichrome bare heating elements are exposed directly to the air stream. Each heater assembly is equipped with an auto-reset temperature limit. Supplemental thermal cut-off fuses are used and are mounted external to the element faceplate for easy access. Elements are sequenced on and off in as many as six steps. Sequencing is controlled by a factory installed thermistor in the unit s air stream. OPTIONAL ECB24 ELECTRIC HEAT All specifications in this manual are subject to change. Page 1

2 SPECIFICATIONS Model No. B24Q2 B24Q3 B24Q3.5 Blower wheel nominal diameter x width in. (mm) 9 x 7 (229 x 178) 10 x 7 (254 x 178) 10 x 8 (254 x 203) 10 x 10 (254 x 254) Blower motor output hp (W) 1/6 (124) 1/3 (249) 1/2 (373) 3/4 (560) Nominal capacity tons (kw) 2 (7.0) 3 (10.6) 3-1/2 (12.3) 4 or 5 (14.1 or 17.6) Number and size of filters (upflow position only) Optional External Filter Kit in. (1) 12 x 20 x 1 (1) 12 x 20 x 1 (1) 15 x 20 x 1 (1) 23 x 20 x 1 mm (1) 305 x 508 x 25 (1) 305 x 508 x 25 (1) 381 x 508 x 25 (1) 584 x 508 x 25 in. (1) 20 x 20 x 1 (1) 20 x 20 x 1 (1) 25 x 20 x 1 (2) 15 x 20 x 1 mm (1) 508 x 508 x 25 (1) 508 x 508 x 25 (1) 635 x 508 x 25 (2) 381 x 508 x 25 Matching Coil Sections Up-flow Down-flow C22-21FC, C22-26FC, C22-31FC, C24-21FC, C24-26FC, C24-31FC CR22-21, CR22-31, CR24-21, CR24-31 C22-26FC, C22-31FC, C24-26FC, C24-31FC, C24-41FC CR22-31, CR24-31 C22-41FC, C24-41WFC, C24-46FC CR22-41, CR24-41 C22-46FC, C22-51FC, C22-65FC, C24-51FC, C24-65FC CR22-51, CR22-65, CR24-51, CR24-65 Horizontal CH22-21, CH22-31, CH24-21, CH24-31 CH22-31, CH24-31 CH22-41, CH24-41 CH22-51, CH22-65, CH24-51, CH24-65 Electrical Characteristics 60hz 208/230V - 1ph 208/230V - 1ph 460V - 1ph 575V - 1ph ECB ECB24-5 ECB24-6 ECB24-7 ECB24-8 Optional Electric ECB24-10 Heat ECB ECB24-15 ECB24-20 ECB24-25 **Output Btuh (kw) 9,500 (2.8) A.F.U.E 100% **Output Btuh (kw) 18,000 (5.3) 18,500 (5.4) 19,000 (5.6) 19,500 (5.7) A.F.U.E 100% 100% 100% 100% **Output Btuh (kw) 21,500 (6.3) 22,000 (6.4) 22,500 (6.6) 23,000 (6.7) A.F.U.E 100% 100% 100% 100% **Output Btuh (kw) 25,000 (7.3) 25,500 (7.5) 26,000 (7.6) 26,500 (7.8) A.F.U.E 100% 100% 100% 100% **Output Btuh (kw) 28,000 (8.2) 29,000 (8.5) 29,500 (8.6) 30,000 (8.8) A.F.U.E 100% 100% 100% 100% **Output Btuh (kw) 35,000 (10.3) 35,500 (10.4) 36,000 (10.4) 37,000 (10.8) A.F.U.E 100% 100% 100% 100% **Output Btuh (kw) ,000 (12.9) 45,000 (13.2) 45,500 (13.3) A.F.U.E % 100% 100% **Output Btuh (kw) ,000 (15.5) 53,500 (15.7) 54,000 (15.8) A.F.U.E % 100% 100% **Output Btuh (kw) ,500 (20.7) 71,000 (20.8) A.F.U.E % 100% **Output Btuh (kw) ,000 (25.8) A.F.U.E % **Output Btuh (kw) ,000 (30.8) ECB24-30 A.F.U.E % **Includes additional blower motor heat capacity. Annual Fuel Utilization Efficiency based on U.S. DOE test procedures and according to FTC labeling regulations (Single phase only). Page 2

3 B24Q2 BLOWER PERFORMANCE B24Q3 BLOWER PERFORMANCE Air Volume at Various Blower Speeds Air Volume at Various Blower Speeds External Static Pressure High Medium Low External Static Pressure High Medium Low in. w.g. cfm cfm cfm in. w.g. cfm cfm cfm NOTE All air data is measured external to the unit. NOTE Electric heaters have no appreciable air resistance NOTE All air data is measured external to the unit. NOTE Electric heaters have no appreciable air resistance. B24Q3.5 BLOWER PERFORMANCE BLOWER PERFORMANCE Air Volume at Various Blower Speeds Air Volume at Various Blower Speeds External Static Pressure High Medium Low External Static Pressure High Medium Low in. w.g. cfm cfm cfm in. w.g. cfm cfm cfm NOTE All air data is measured external to the unit. NOTE Electric heaters have no appreciable air resistance NOTE All air data is measured external to the unit. NOTE Electric heaters have no appreciable air resistance. Page 3

4 Blower Unit Model No. OPTIONAL ELECTRIC HEAT DATA 208/240V Single-Phase Electric Heat *Minimum Circuit Ampacity No. of Stages Volts kw **Btuh Unit Model No. & Phase Input Input Input & Shipping Weight Circuit 1 Circuit , B24Q2 ECB Stage , (6 lbs.) (3 kg) 1 Phase , , , Stage , B24Q2 B24Q3 ECB24-5 (6 lbs.) (3 kg) B24Q3.5 ECB24-5CB (7 lbs.) (3 kg) 1 Phase , , , , B24Q2 B24Q3 ECB Stages B24Q3.5 (7 lbs.) (3 kg) 1 Phase , , , , B24Q2 B24Q3 ECB Stages B24Q3.5 (7 lbs.) (3 kg) 1 Phase , , , Stages , B24Q2 B24Q3 ECB24-8 (7 lbs.) (3 kg) B24Q3.5 ECB24-8CB (8 lbs.) (4 kg) 1 Phase , , , Stages , B24Q2 B24Q3 ECB24-10 (7 lbs.) (3 kg) B24Q3.5 ECB24-10CB (8 lbs.) (4 kg) 1 Phase , , , B24Q3 ECB CB 3 Stages , B24Q3.5 (10 lbs.) (5 kg) 1 Phase , , , B24Q3 ECB24-15CB 3 Stages , B24Q3.5 (10 lbs.) (5 kg) 1 Phase , , , B24Q3.5 ECB24-20CB 4 Stages , (12 lbs.) (5 kg) 1 Phase , , , ECB24-25CB 6 Stages , (16 lbs.) (7 kg) 1 Phase , , , ECB24-30CB 6 Stages , (16 lbs.) (7 kg) 1 Phase , , *Refer to National or Canadian Electrical Code to determine wire, fuse and disconnect size requirements. Use wire suitable for at least 167 F (75 C). **Electric heater capacity only does not include additional blower motor heat capacity. Page 4

5 Blower Unit Model No. OPTIONAL ELECTRIC HEAT DATA 208/240V Three-Phase Electric Heat *Minimum Circuit Ampacity No. of Stages Volts kw **Btuh Unit Model No. & Phase Input Input Input & Shipping Weight Circuit 1 Circuit , B24Q2 B24Q3 ECB Stages B24Q3.5 (7 lbs.) (3 kg) 3 Phase , , , , B24Q2 B24Q3 ECB Stages B24Q3.5 (7 lbs.) (3 kg) 3 Phase , , , , B24Q2 B24Q3 ECB Stages B24Q3.5 (7 lbs.) (3 kg) 3 Phase , , , , B24Q3 B24Q3.5 ECB24-15F (9 lbs.) (5 kg) 3 Stages 3 Phase , , , , ECB24-20F 20F (13 lbs.) (6 kg) 6 Stages 3 Phase , , , , ECB24-25F 25F (13 lbs.) (6 kg) 6 Stages 3 Phase , , , *Refer to National or Canadian Electrical Code to determine wire, fuse and disconnect size requirements. Use wire suitable for at least 167 F (75 C). **Electric heater capacity only does not include additional blower motor heat capacity. Page 5

6 Blower Unit Model No. OPTIONAL ELECTRIC HEAT DATA 460V Three-Phase Electric Heat No. of Stages Volts kw **Btuh *Minimum Unit Model No. & Phase Input Input Input Circuit Ampacity & Shipping Weight , ECB24-10F (12 lbs.) (5 kg) 3 Stages 3 Phase , , , ECB24-15F (12 lbs.) (5 kg) 3 Stages 3 Phase , , , ECB24-20F (12 lbs.) (5 kg) 3 Stages 3 Phase , , , ECB24-25F (12 lbs.) (5 kg) 3 Stages 3 Phase , , *Refer to National or Canadian Electrical Code to determine wire, fuse and disconnect size requirements. Use wire suitable for at least 167 F (75 C). **Electric heater capacity only does not include additional blower motor heat capacity. Blower Unit Model No. OPTIONAL ELECTRIC HEAT DATA 575V Three-Phase Electric Heat No. of Stages Volts kw **Btuh *Minimum Unit Model No. & Phase Input Input Input Circuit Ampacity & Shipping Weight , ECB24-15F (12 lbs.) (5 kg) 3 Stages 3 Phase , , , ECB24-20F (12 lbs.) (5 kg) 3 Stages 3 Phase , , , ECB24-25F (12 lbs.) (5 kg) 3 Stages 3 Phase , , *Refer to Canadian Electrical Code to determine wire, fuse and disconnect size requirements. Use wire suitable for at least 167 F (75 C). **Electric heater capacity only does not include additional blower motor heat capacity. Page 6

7 I - APPLICATION B24 series blowers are available with nominal blower capacities ranging from 2, 3, 3 1/2 and 4 or 5 tons. Any unit can be used in upflow, downflow or horizontal position. See figures 1, 2 and 3. Optional electric heat sections are available in sizes ranging from 2.5 thru 30 kw. FILTER CABINET TYPICAL DOWNFLOW APPLICATION TYPICAL UPFLOW APPLICATION C22 or C24 COIL B24 BLOWER B24 BLOWER C22 or C24 COIL FIGURE 3 CABINET CONNECTING PINS CABINET SECTIONS SNAP TOGETHER WITH BARREL SHAPED CONNECTING PINS. FIGURE 1 AIR FLOW BLOWER TOP VIEW CONNECTORS (4) (Furnished with Blower Unit) TYPICAL HORIZONTAL APPLICATION B24 BLOWER C22 or C24 COIL FILTER CABINET FIGURE 4 CABINET SUSPENSION INSERTS AIR FLOW BLOWER TOP VIEW FIGURE 2 The B24 is designed to matchup to the C22/C24 coil series. The B24/C22 or C24 are fastened together by four interlocking pins. See figure 4. Pins are supplied with the B24. The B24 may also be used as stand-alone blower or electric furnace when cooling is not required. 1/4-20 THREADED INSERTS ALLOW UNIT TO BE SUSPENDED BY ALLTHREAD. FIGURE 5 All B24 units (including 460V and 575V units) utilize single phase electrical components and blower motor. If three-phase power is supplied to the unit and optional electric heat is not used, one power leg is not connected. 208/230V units (B24-P) can be used with single-phase heaters (ECB24-P) or three-phase heaters (ECB24-Y). 460V units (B24-G) uses 460V heaters (ECB24-G). 575V units (B24-J) uses 575V heaters (ECB24-J). Page 7

8 All major components (indoor blower / coils) must be matched according to Lennox recommendations for the compressor to be covered under warranty. Refer to the Engineering Handbook for approved system matchups. A misapplied system will cause erratic operation and can result in early compressor failure. II - UNIT COMPONENTS ELECTRIC HEAT OPENING DISCHARGE AIR SENSOR B24 COMPONENTS CONTROL BOX BLOWER HARNESS Unit components are shown in figure 6 and control box components are shown in figure 8. The B24 control box may be accessed by removing the two screws securing the blower access in place. The blower panel lifts and slides out of place. The top edge is rolled allowing the cover to be reinstalled to allow access to the control box while sealing off the blower compartment. See figure 7. B24 SERVICE When servicing a B24 installed in the upflow position, the blower access panel can hang on the control box flange as shown. This will permit an airtight seal while performing unit checkout procedures. FIGURE 6 BLOWER BLOWER MOTOR CAPACITOR FIGURE 7 HANG ACCESS PANEL ON CONTROL BOX FLANGE WHILE SERVICING UNIT. DISCHARGE AIR SENSOR OPENING FOR NAR- ROW FRAME ECB24 ELECTRIC HEAT B24 CONTROL BOX P VOLTAGE (208/230V) CONTROL TRANSFORMER BLOWER CONTROL OPENING FOR WIDE FRAME ECB24 ELECTRIC HEAT NOTE Q2, Q3 and Q3.5 blowers have narrow electric heat opening only. LINE VOLTAGE PIGTAILS BLOWER MOTOR HARNESS B24 CONTROL BOX G VOLTAGE (460V) AND J VOLTAGE (575V) NOTE Q2, Q3 and Q3.5 blowers have narrow electric heat opening only. DISCHARGE AIR SENSOR OPENING FOR NAR- ROW FRAME ECB24 ELECTRIC HEAT OPENING FOR WIDE FRAME ECB24 ELECTRIC HEAT BLOWER TRANSFORMER (575V ONLY) LINE VOLTAGE OR ELECTRIC HEAT HOOKUP BLOWER SPEED CHANGE TERMINAL BLOCK FIGURE 8 BLOWER RELAY BLOWER CONTROL DOOR INTERLOCK SWITCH CONTROL TRANSFORMER BLOWER MOTOR HARNESS Page 8

9 B24 control box is is illustrated in figure 8. Optional electric heat fits through an opening in the center of the control box. A filler plate covers this opening when no electric heat is used. Electric heat control arrangement is covered in OPTIONAL ELECTRIC HEAT section. TYPICAL ELECTRIC HEAT INSTALLATION ELECTRIC HEAT OPENING CONTROL BOX OPTIONAL ECB24 ELECTRIC HEAT FIGURE 9 A - Control Transformer T1 P Voltage Units (208/230V) All B24 series units use a single primary voltage to 24VAC transformer located in the control box. The transformer supplies power to the control circuits in the indoor and outdoor units as well as the thermostat. The transformer in 230V units is rated 43VA and PRIMARY ORANGE 240 VOLTS RED 208 VOLTS BLACK BLUE SECONDARY 208 / 240 VOLT TRANSFORMER T1 YELLOW FIGURE 10 has two primary voltage taps as shown in figure 10. In 460V and 575V units, T1 uses 460V primary voltage and is rated 60VA. In 575V units, line voltage is stepped down to provide 460V for transformer T1. B - Low Voltage Fuse F1 P Voltage Units (208/230V) Located on the A45 control module, fuse F1 protects all low voltage controls in the unit. F1 is a 3 amp automotive spade type plug-in fuse. The fuse is connected in series with the blue 24V transformer output wire. It is used to protect all 24V controls which are powered by transformer T1. C - Low Voltage Fuse F1 G & J Voltage Units (460 & 575V) Located inline with the blue transformer wire, fuse F1 protects all low voltage controls in the unit. F1 is a 3 amp AGC type glass fuse. D - Blower Fuse F7 P Voltage Units Only (208/230V) Located on the A45 control module, Fuse F7 protects the blower and all line voltage components in the B24. F7 is an AGC TABLE 1 Fuse F7 208V & 230V Units Only Blower Motor Fuse F7 Rating (amps) Q2 1.5 Q3 3.2 Q Q4/ type glass fuse. Its amp rating varies with blower size. E - Door Interlock Switch 460V and 575V units are equipped with door interlock switch located adjacent to the control transformer in the control box. The switch is a SPST momentary type push-button switch which is normally closed when the blower access panel is in place. The switch is positioned so it opens when the blower access door is opened. When the switch opens, the 24VAC circuit to blower control A45 is interrupted and all unit operation stops. F - Blower Control Module A45 Blower control A45 is shown in figures 11 and 12. In heating mode, the control coordinates optional electric heat operation with the blower. In cooling mode, the control coordinates blower operation with the compressor. The control does not affect compressor operation in any way. The operating sequence of the control changes depending on application, matchup and operating mode. Many of the control board s functions are controlled by the discharge air sensor while other functions are controlled by internal timers. The discharge air sensor is calibrated as shown in table 3. Blower operating sequence and speed are not affected when applied to a two-speed system. However, a field installed kit (208/230V) or field supplied, field installed relays (460V or 575V) may be used if blower speed changes are desired with compressor speed change. Thermostat connections can be made to the low voltage terminal strip located on the circuit board. Terminals Y2 and W2 provide a place for making low voltage connections but do not affect control operation. Terminals W2 and E are not capable of enabling or energizing electric heat. However, when E is energized, electric heat will cycle faster. Blower FAN ON Operation The blower operates anytime G, Y, or W1 are energized. After a demand is received, there will be a delay of up to 2 seconds before the blower will start. When blower demand is removed, the blower turns off within 2 seconds. Blower Operation - Air Conditioning Cooling (with or without electric heat) Y1 should be jumpered to O on low voltage terminal strip. After a demand is received, the compressor will be energized immediately (by indoor thermostat) and there will be a delay of approximately 1 second before the blower will start. When indoor thermostat demand is satisfied, the blower is turned off when discharge air temperature rises above 65 F (see table 2). Page 9

10 A45 BLOWER CONTROL BOARD COMPONENTS 208/240V UNITS LOW VOLTAGE TERMINAL STRIP FUSE F1 (located underneath terminal strip) (1/4 in. FEMALE SPADES) COMMON ELECTRIC HEAT LOCKOUT TEMPERATURE ADJUSTMENT DISCHARGE AIR SENSOR HOOKUP (1/4 in. MALE SPADE) L2 LINE VOLTAGE COMMON BLOWER COMMON P2 ELECTRIC HEAT HARNESS CONNECTION FIGURE 11 DIAGNOSTIC LED LOW SPEED TAP MED. SPEED TAP 24VAC INPUT HIGH SPEED TAP FUSE F7 FAN SPEED JUMPER SELECT IDLE (Continuous Low Blower) L1 LINE VOLTAGE PRIMARY TRANSFORMER PARK A45 BLOWER CONTROL BOARD COMPONENTS 460V and 575V UNITS COMMON LOW VOLTAGE TERMINAL STRIP DIAGNOSTIC LED ELECTRIC HEAT LOCKOUT TEMPERATURE ADJUSTMENT DISCHARGE AIR SENSOR HOOKUP (1/4 in. MALE SPADE) P2 ELECTRIC HEAT HARNESS CONNECTION DANGER Electrical Shock Hazard. Single phase blower control A45. This control contains field adjustable connections and also contains line voltage. Make sure power is disconnected before making any field adjustments or performing any service procedure. Blower Operation - Heat Pump Cooling When Y and O cooling demand is received, blower begins operating within 2 seconds.when indoor thermostat demand is satisfied, the blower is turned off when discharge air temperature rises above 65 F (see table 2). Blower Operation - Heat Pump Heating After demand (Y) is received, the compressor will be energized immediately (by indoor thermostat) and there will be a delay of about 2 seconds before the blower will start. When indoor thermostat demand is FIGURE 12 24VAC INPUT BLOWER RELAY OUTPUT ELECTRICAL COMMON ECONOMIZER OUTPUT BLOWER RELAY OUTPUT 24VAC ELECTRIC HEAT OUTPUT satisfied, the blower is turned off when discharge air temperature drops below 90 F (see table 2). In twospeed applications, compressor speed is controlled by the speed control thermostat in the outdoor unit, and in some cases, the indoor thermostat. In either case, B24 operating sequence is not affected TABLE 2 System Air Conditioning with Electric Heat Blower Off Temperatures Type of Demand Blower Response After Demand is Satisfied Demand Thermostat Connections Discharge Discharge Air Sensor Air Sensor In Place Absent Blower G Off Within 2 sec. Heat W1 Temp 90 F or Less Cool Y Temp 65 F or Greater Blower G Off Within 2 sec. Heat Y Temp 90 F or Less Heat Pump with or with- out Auxiliary Heat Em. Heat W1 Temp 90 F or Less Cool Y and O Temp 65 F or Greater Off Within 2 sec. 10 seconds 45 seconds Off Within 2 sec. 10 seconds 10 seconds 45 seconds Page 10

11 Blower Operation - Electric Heat in Air Conditioning/Heating Applications When W1 heating demand is received, the blower begins operating within 1 second later. Elements will cycle on at 10 second intervals until discharge temperature balance point is reached. When demand is removed, the heating elements begin sequencing off at 1 second intervals. For example, if six elements are operating, all elements should be turned off within 6 seconds. After the last element is turned off, the blower is turned off when discharge air temperature drops below 90 F. Troubleshooting Tip If the discharge air sensor is open or disconnected and W1 demand is present, all heating elements will sequence on at 10 second intervals. Blower Operation - Auxiliary Electric Heat in Heat Pump Applications Field adjustable lockout temp is invoked (see table 3). Elements will cycle on at 10 second intervals until discharge temperature balance point is reached. Blower operates same as when heat pump heating except all heating elements must completely turn off and discharge air temperature must drop below 90 F before blower can be turned off. Troubleshooting Tip If the discharge air sensor is open or disconnected and Y and W1 demand are both present, all heating elements will sequence on at 60 second intervals. Blower Operation - Emenrgency Heat in Heat Pump Applications When W1 heating demand is received, the blower begins operating within 1 second later. Elements will cycle on at 10 second intervals until discharge temperature balance point is reached. When demand is removed, the heating elements begin sequencing off at 1 second intervals. For example, if six elements are operating, all elements should be turned off within 6 seconds. After the last element is turned off, the blower is turned off when discharge air temperature drops below 90 F. Safety Limit If the discharge air thermistor senses discharge air warmer than 170 F and G, Y or W1 inputs are not present, the blower will be turned on and will remain on until system power is turned off. At the same time, the control will lock out electric heat operation. The control will automatically reset when the fault is corrected and system power is restored. Troubleshooting Tip If the discharge air sensor is shorted, the blower will operate in Safety Limit mode. TABLE 3 Discharge Air Temperature Sensor KOhms Temp. C Temp. F A45 Response Cooling Blower Off Heating Blower Off Adjustable Heat Pump Lockout Temperature: Locks Out Elec- tric Heat When Discharge Air is Warmer Than ,90, 95 or Stage On Element Electric Heat Discharge Air Sensor Tries to Maintain Temperature In This Range Stage Off 1 Element Stage Off Elements Safety Limit Blower On All Elements Off Page 11

12 Blower control A45 continuously monitors the discharge air temperature. As long as discharge air temperature remains above a preset limit, auxiliary heating is locked out. When discharge air temperature drops below the preset limit, the electric heating elements are allowed to stage on to provide auxiliary heating. Heat Pump Balance Point (Lockout Temperature) In heat pump applications, the B24 does not require an outdoor thermostat to sense the balance point (heat loss = heat gain). In heat pump heating, discharge air temperature is directly related to outdoor air temperature. As outdoor temperature drops, so does indoor unit discharge air temperature. This means the balance point can be indirectly sensed by measuring the discharge air temperature. Some local utilities require that the auxiliary heating elements be automatically locked out when outdoor air temperature rises above a pre-determined outdoor air temperature. This may be controlled by the B24 using the discharge air sensor. In either case, the switchover point can be adjusted by changing a jumper on the B24 control board. If the setting requires adjustment follow the procedure shown in figure F 90 F 95 F 100 F or 100 F Plug J2 from ECB24 into plug on B24 Control Board. Set Jumper on Desired Lockout Temperature. Use of Outdoor Thermostats To Control Electric Heat Stages B24 Control Board Outdoor thermostats are not required and should not be installed on ECB24 series heaters. A single outdoor thermostat may be installed in series with the W1 low voltage connection on the blower control A45. When installed in this manner, the outdoor thermostat locks out all electric heat operation when outdoor temperature is below a field adjustable setpoint. Some local utilities require outdoor thermostats installed to lockout heating stages when outdoor temperature is low. This function is built-in to the B24 blower control board and eliminates the need for outdoor thermostats. Indoor unit discharge air temperature is directly related to outdoor air temperature. As outdoor temperature drops, heat loss increases. As heat loss increases, indoor unit return air temperature drops. This means that outdoor temperature can be indirectly sensed by measuring the discharge air temperature. When outdoor temperature is mild and heat loss is low, return air tempeature is warmer and fewer elements are required in order to maintain discharge air temperature. The discharge air sensor can sense this condition and locks out all unnecessary elements. When outdoor temperature is cold and heat loss is high, return air temperature is cooler and more elements are required in order to maintain discharge air temperature. The discharge air sensor stages on additional elements in order to compensate for the additional loading. Outdoor thermostats cannot be installed to control subsequent (2nd, 3rd, 4th, 5th or 6th) stages of electric heat. W2 low voltage connection does not provide any staging function. Do not attempt to install additional staging by altering the electric heat harness. Diagnostic LED A red LED located on the blower control board lights to indicate normal operation and error conditions. The LED will remain on, or display differing flashes indicating control board states. Table 4 shows how to interpret the LED. TABLE 4 Blower Control Board A45 Diagnostic LED LED State Meaning Remedy Steady On Normal Operation Slow Flash (1 sec. on 1 sec. off) Fast - Double Flash Limit S15 Currently Open Indoor Blower Will Be Locked On and Electric Heat Will Be Locked Out Until S15 Automatically Resets. Limit S15 Has Opened Fourth Time Indoor Blower Will Be Locked On and Electric Heat Will Be Locked Out Until Unit Power is Turned Off Then Turned On. Remove Thermostat Demand, Allow S15 to Cool Then Troubleshoot Electric Heater Remove Thermostat Demand, Momentarily Turn Off Power To Unit, Then Troubleshoot Electric Heater G - Discharge Air Sensor RT1 The discharge air sensor RT1 (figure 15) is a Negative Temperature Coefficient (NTC) Thermistor located in the discharge air stream inside the B24 blower. The sensor is electrically connected to the A45 blower control and provides discharge air temperature sens- Page 12

13 ing. As discharge temperature goes up, resistance through the sensor goes down. Table 3 shows the relationship between discharge air temperature and resistance through the sensor. DISCHARGE AIR SENSOR ACCESS RAIL TABS 4 3 SLOTS IN REAR PANEL TO ACCESS DISCHARGE AIR SENSOR RT1: 1-Turn off power. Disconnect power wires and Jack J2. 2-Remove ECB24 electric heat section from unit. 3-Remove screw supporting sensor rail and hinge entire assembly downward. 4-Disconnect sensor wires. 5-Slide rail out of slots in rear panel and remove entire assembly from unit. 6-When reinstalling assembly, carefully align rail tabs with slots in rear panel. Secure all wires and screws. Reinstall electric heat and reconnect harness. Double check installation and wiring before turning on power to unit. FIGURE 14 5 IMPORTANT Avoid blower damage. Small parts dropped onto blower assembly (upflow units) or coil (downflow units) can cause unit damage. Remove entire sensor assembly from unit before servicing sensor. The sensor can be checked by ohm ing-out with a volt/ ohm meter. Be sure to turn off unit power before performing this test and disconnect one of the leads from the blower control board. When you check the sensor, compare your reading to the values listed in table 3. Remember that heat from your hands can change the resistance through the sensor. If the sensor is open or shorted, or if the sensor is out of calibration more than +10% of the value shown in table 3, replace the sensor. DISCHARGE AIR SENSOR RT1 FIGURE SENSOR SENSOR RAIL The sensor can be accessed through the electric heat opening in the B24. If electric heat is installed, it must be removed. Figure 14 shows how to access the sensor. H - Blower Relay K3 G & J Voltage Units Only (460 & 575V) Relay K3 is a 24V single-pole double-throw relay used to control the blower. The relay coil is connected to blower relay terminals located on the A45 control board. The relay is wired as shown on the unit wiring diagram. I - Optional Economizer Relay K43 Relay K43 is a 24V single-pole double-throw relay which is used to control an economizer. In 460V and 575V units, the relay coil is connected to ECON terminals located on the A45 blower control board. In 208/230V units the relay is hard wired as shown on the unit wiring diagram. NOTE If economizer is installed, transformer T1 must be replaced with 70VA transformer. J - Transformer T4 (575V only) 575V units are equipped with a line voltage to 460V transformer (in addition to T1) located in the control box. T4 is a center-tap auto-transformer which provides 460V power to the blower motor only. K - Blower Terminal Strip TB25 G & J Voltage Units Only (460 & 575V) 460V and 575V units are equipped with a terminal strip for connecting and changing blower speed taps. This terminal strip provides a connection point for connecting the blue internal motor lead which is required for proper motor operation. See unit wiring diagram for speed tap connections. L - Blower Motor B3 All B24 series blowers use single phase PSC blower motors. A single run capacitor is mounted on the blower housing. All motors use multiple speed taps. With the addition of a blower speed relay kit (208/230V) or field supplied, field installed relays (460V and 575V), the high speed tap is energized during compressor operation and a lower speed tap is energized during heat operation. Blower motors in P voltage (208/230V) units have three speed taps and are leadless type. G voltage (460V) motors also have three speed taps plus a blue wire for connecting an internal circuit. Blower motor specifications are listed in table 5. Blower specifications are listed in the specifications tables in the front of this manual. TABLE 5 BLOWER MOTOR 1075 RPM CCW ROTATION Unit Volts Phase HP FLA B24Q2 P 208/ /6 1.1 B24Q3 P 208/ /3 2.4 B24Q3.5 P 208/ /2 3.6 P 208/ /4 3.8 G or J /4 1.9 Page 13

14 TABLE 6 MINIMUM BLOWER SPEED B24 Blower Section ECB24 Heat Section Minimum Blower Speed B24Q2 5 kw or less LOW 6kW or more MEDIUM B24Q3 All Heat Sections LOW B24Q3.5 All Heat Sections LOW All Heat Sections MEDIUM All units are factory wired for high speed operation. Field adjustment may be required depending on matchup and application. See table 6. All speeds shown are minimums. Do not change motor taps to operate at speeds lower than those shown in table 6. Speed Tap Adjustment 208/230V Units are factory equipped to operate on the same speed during heating and cooling. This speed may be adjusted between high, medium and low as required. However, blower must never be operated below the minimum speed listed in table 6 when an ECB24 is used. All units use single-phase three-speed motors. All motor leads are routed back to the control box so that blower speed changes can be made at the blower control. Figure 16 shows how to make blower speed changes. 208/230V BLOWER SPEED ADJUSTMENT A45 BLOWER CONTROL SPEED JUMPER LEAVE THIS END CONNECTED BLACK YELLOW RED BLUE BLACK YELLOW RED TO BLOWER MOTOR TO BLOWER RELAY Park Wire In 2 Blue Terminal FIGURE V AND 575V UNITS LOW BLOWER SPEED CONTROL BOX BLUE BLACK TO BLOWER MOTOR TO BLOWER RELAY BLUE 460V AND 575V UNITS MEDIUM BLOWER SPEED CONTROL BOX BLUE BLACK TO BLOWER MOTOR TO BLOWER RELAY BLACK YELLOW RED BLUE 460V AND 575V UNITS HIGH BLOWER SPEED CONTROL BOX BLACK BLUE 1 Remove Blue Wire PLACE JUMPER ON HIGH FOR HIGH SPEED PLACE JUMPER ON MED FOR MEDIUM SPEED PLACE JUMPER ON LOW FOR LOW SPEED DANGER Electrical Shock Hazard. 208/240V units only. This control contains field adjustable connections and also contains line voltage. Make sure power is disconnected before making any field adjustments or performing any service procedure. FIGURE 16 Speed Tap Adjustment 460V and 575V The blue tap on 460 volt motors is used for internal wiring during low speed operation and must not be connected to line voltage. During low speed (red tap) operation, the high speed (black tap) is disconnected from line voltage and is connected to the blue internal wiring tap (see figure 17). DANGER Electrical Shock Hazard. All blower speed change connections contain high voltage. Make sure power is disconnected before attempting to change blower speed. M - Blower Motor Capacitor The blower motor in all B24 units is a single-phase PSC type motor which requires a run capacitor. A single capacitor located on the blower housing is used for the blower motor. Table 7 shows the capacitor ratings. TABLE 7 BLOWER MOTOR CAPACITOR RATINGS Unit MFD VAC B24Q2 P 5 B24Q3 P 5 B24Q3.5 P P 10 G or J 10 Page 14

15 N - Optional Blower Speed Control Kit Optional blower relay kit may be field installed on any 208/230V B24 unit to allow the blower to operate at a different speed during high speed compressor operation or during electric heat operation see figure 18. This kit may be installed in any convenient location in the unit control box. The same controlling functions can be accomplished in 460V and 575V units by installing field supplied, field installed relays as shown in figure 19. See instruction included with kit for more information. Figure NO TAG and NO TAG shows how to field wire a typical B24 unit for high speed cooling and lower speed heating. In heat/cool applications (non-heat pump), the blower speed relay can be installed to provide high speed blower operation during cooling. During electric heat operation, the optional blower speed relay is energized and the relay contacts switch the indoor blower to low speed. In two-speed applications (air conditioning or heat pump), the blower speed relay can be installed to provide low speed blower operation while the compressor is operating on low speed. When the compressor switches to high speed, the blower speed relay is energized the relay contacts switch the indoor blower to high speed. Page 15

16 OPTIONAL BLOWER SPEED CONTROL KIT 208/230V UNITS OPTIONAL FACTORY SUPPLIED, FIELD INSTALLED COMPONENTS FIGURE 18 Page 16

17 OPTIONAL BLOWER SPEED CONTROL RELAYS 460V and 575V UNITS FIELD SUPPLIED, FIELD INSTALLED COMPONENTS FIGURE 19 Page 17

18 III - OPTIONAL ELECTRIC HEAT Typical ECB24 units are shown in figures 22, 23, 24 and 25. The heaters are provided with line voltage overcurrent protection as shown in table 8. Note that some models are available with or without protection. TABLE 8 ECB24 LINE VOLTAGE OVERCURRENT PROTECTION Unit Type of Protection ECB24 Single-Phase Less Than 10Kw ECB24 Three-Phase Less Than 10Kw ECB24 Single-Phase 5Kw, 8Kw, 10Kw ECB24 Single-Phase Larger Than 10Kw ECB24 Three-Phase 208/230V 15Kw and Larger ECB24 Three-Phase 460V and 575V All Sizes Non-Fused Push-Button Circuit Breaker Class T Fuse All units are equipped with primary and secondary overtemperature protection. The discharge air temperature sensor (located in the B24 blower and controlled by the A45 blower control) provides redundant thermal protection. A - Door Interlock Switch 208/230V three-phase heaters 15Kw and larger are equipped with a door interlock switch located on the face of the control panel. The switch is a SPST momentary type push-button switch which is normally closed when the blower access panel is in place. The switch is positioned so it opens when the blower access door is opened. When the switch opens, the L2 line voltage circuit to blower control A45 is interrupted and all unit operation stops. B - Sequencer Control A36 Elements are sequenced on and off in as many as six steps. Sequencing is controlled by a factory installed thermistor in the unit s air stream. See figure 20. The primary function of sequencer A36 is to provide pilot relay switching of the heating elements. TABLE 9 ECB24 TO B24 WIRING HARNESS B24 PIN (A45 CONTROL BOARD) ECB24 PIN (A36 CONTROL BOARD) FUNCTION PWR1 PWR1 24VDC Power To ECB24 LIMIT LIMIT S15 Limit Sensing PWR2 PWR2 24VDC Power To ECB24 5 HTR5 24VDC From Fifth Stage Sequencer 2 HTR2 24VDC From Second Stage Sequencer 1 HTR1 24VDC From First Stage Sequencer 4 HTR4 24VDC From Fourth Stage Sequencer 3 HTR3 24VDC From Third Stage Sequencer 6 HTR6 24VDC From Sixth Stage Sequencer Blank GND Ground Blank Not Used L L2 Line Voltage Blank Not Used L L1 Line Voltage The sequencer is controlled externally by the A45 blower control and the discharge air sensor RT1. The sequencer is controlled internally only by limit S15. All timing and temperature functions (except for limit S15) are controlled by blower control A45. The sequencer is connected to the blower control by way of a flat wire harness (figure 20). Table 9 shows the purpose of each wire in the flat wire harness. HTR1 1st STAGE SEQUENCER RELAY HTR2 2nd STAGE SEQUENCER RELAY HTR5 5th STAGE SEQUENCER RELAY SEQUENCER CONTROL A36 TWO STAGE (TWO RELAY) SHOWN JACK J2 DANGER FIGURE 20 PLUG P2 ECB24 S15 HIGH TEMPERATURE LIMIT HTR6 6th STAGE SEQUENCER RELAY HTR3 3rd STAGE SEQUENCER RELAY HTR4 4th STAGE SEQUENCER RELAY A36 SEQUENCER CONTROL ELECTRIC SHOCK HAZARD. RELAY CONTACTS ARE POWERED BY LINE VOLTAGE. TURN OFF POWER BE- FORE PERFORMING ANY SERVICE PROCEDURE. C - Thermal Fuses F5 All ECB24 series units use high temperature (thermal) cutoff fuses connected in series with each element (figure 21). Fuses provide secondary high temperature protection to each element. The fuses are ceramic one-shot fusible links which must be replaced after being tripped. THERMAL CUTOFF FUSE F5 FIGURE 21 HIGH TEMPERATURE LIMIT S15 The trip temperature is different depending on unit model number. This information is printed on the side of the limit. Generally, the limit is factory set to trip when discharge air temperature rises above 168 F to 257 F. Page 18

19 TYPICAL SMALL kw SINGLE-PHASE and THREE-PHASE ECB24 HEATER (WITH TERMINAL BLOCK) LIMIT S15 HEATING ELEMENTS TERMINAL BLOCK TB3 (FIELD WIRING CONNECTIONS) HEAT RELAY HR1 HEAT RELAY HR2 FUSE F5 P85/J85 JACKPLUG A36 SEQUENCER CONTROL J2 JACK FIGURE 22 TYPICAL LARGE kw SINGLE PHASE ECB24 HEATER (WITH CIRCUIT BREAKER) FUSE F5 LIMIT S15 HEATING ELEMENTS CIRCUIT BREAKER CB1 CIRCUIT BREAKER CB2 FUSE F5 CIRCUIT BREAKER CB3 A36 SEQUENCER CONTROL J2 JACK P85/J85 JACKPLUG FIGURE 23 Page 19

20 TYPICAL 208/230V THREE PHASE ECB24 HEATER (WITH FUSES) LIMIT S15 HEATING ELEMENTS FUSE F5 FUSE BLOCK F3 FUSES FUSE F5 DOOR INTERLOCK SWITCH A36 SEQUENCER CONTROL J2 JACK P85/J85 JACKPLUG FIGURE 24 TYPICAL 460V AND 575V THREE PHASE ECB24 HEATER (WITH FUSES) FUSE BLOCK F3 FUSES SECONDARY LIMIT S20 ELECTRIC HEAT RELAY K15 LIMIT S15 HEATING ELEMENTS SECONDARY LIMIT S20 ELECTRIC HEAT RELAY K16 ELECTRIC HEAT RELAY K17 A36 SEQUENCER CONTROL J2 JACK P85/J85 JACKPLUG FIGURE 25 Page 20

21 ECB24 TO B24 WIRING HARNESS PLUG P2 BLOWER CONTROL A45 SEQUENCER A36 PLUG P85 JACK J86 JACK J2 LINE VOLTAGE L2 LINE VOLTAGE L2 FIGURE 26 D - Line Voltage Terminal Block TB3 Single-Phase and Three-Phase ECB24 heaters 10kW and smaller are equipped with a line voltage terminal block for field connection of line voltage. Figure 22 shows a typical line voltage terminal block used in ECB24 heaters. E - Electric Heat Relays K15, K16 and K17 Relays K15, K16 and K17 are pilot relays used to energize the heating elements in 460V and 575V units. K15 controls the first stage heating element, K16 controls the second stage heating element and K17 controls the third stage heating element (see figure 25). Each relay is a 24VAC SPST relay. The coil of each relay is connected to the heat sequencer A36. Sequencer A36 steps the relays on in a first on last off sequence. F - Line Voltage Fuses F3 ECB24 heaters listed in table 8 are equipped with Class T fuses providing overcurrent protection. Each leg of line voltage is equipped with its own fuse. G - Circuit Breakers CB1, CB2 All single-phase ECB24 heaters larger than 10kW are equipped with line voltage circuit breakers for line voltage overcurrent protection. 5Kw, 8Kw and 10Kw single-phase heaters are also available with or without circuit breakers. The circuit breakers are connected to line voltage and serve as a terminal block for connecting line voltage. Single-phase and three-phase heaters 10kW and under are not equipped with circuit breakers. Instead, they are equipped with a terminal block for connecting line voltage. 5Kw, 8Kw and 10Kw single-phase heaters are also available with or without circuit breakers. ECB24 series units are equipped with a unique pushbutton type circuit breaker (figure 27). Each circuit straddles the circuit breaker mounting panel located on the ECB24. The breakers are located so they can be reset or switched off without removing the B24 front access cover. The breakers are switched on and off and can be reset by pushing in on the breaker until an audible click is heard. A display window in the front of each breaker displays the current status. The trip current is different depending on model number. This information is printed on the side of the breaker. Each breaker is held in place by a retainer (figure 27) and is held in alignment by an alignment pin. A breaker can be easily removed by first removing the retainer then sliding the breaker off the mounting panel. When re-installing a breaker, make sure the alignment pin is positioned correctly. H - Primary Limit S15 Each ECB24 uses an auto-reset type high temperature limit connected to the sequencer control A36 (figure 20). The high temperature limit is used as a primary limit. If the switch exceeds its factory preset limit (printed on side of limit), it opens and instantly turns off all heating elements and locks the blower on. While the limit is open, the diagnostic LED located on the blower control board will flash. Once the limit closes, the electric heat will resume normal operation. Page 21

22 L1 LINE VOLTAGE HOOKUP* ECB24 CIRCUIT BREAKERS TWO-POLE SHOWN FOR SINGLE PHASE HEATERS ECB24 CIRCUIT BREAKER CIRCUIT BREAKER MOUNTING PANEL RETAINER REMOVAL / INSTALLATION ECB24 CIRCUIT BREAKER ALIGNMENT PIN ALIGNMENT HOLE PUSH CLICK ON PUSH CLICK OFF CURRENT RATING DISPLAY WINDOW ON OFF (TRIPPED) L2 LINE VOLTAGE HOOKUP* CIRCUIT BREAKER MOUNTING PANEL RETAINER *Line voltage hookup may be made as shown or to Buss Bar (not shown). 1/4 SPADE TERMINALS FIGURE 27 If the limit opens four times during the same heating LIMIT S15 ACCESS demand, the blower control board will lock out and remain locked out even after S15 closes. During this time ECB24 the electric heat will be locked out and the blower will SENSOR OPENING remain locked on. This lockout condition can only be reset by momentarily turning off power to the B24 then turning power back on. PLUG P2 JACK J2 S15 HIGH TEMPERATURE LIMIT A36 SEQUENCER CONTROL TO REMOVE LIMIT S15: 1-Turn off power. Disconnect Jack J2. 2-Remove A36 sequencer from unit. 3-Grasp control board with one hand and limit S15 with other hand. Gently remove limit from board by pulling straight outward. 4-Replace limit by snapping limit into slots in control board. 5-Re-install A36 sequencer control. Reconnect all wires and turn on power. FIGURE 28 The limit is connected to the back side of the A36 sequencer control. The limit snaps into the control board with 1/4 spade terminals (see figure 28). The face of the limit fits through an opening in the ECB24. This allows the limit to monitor airstream temperatures without being electrically exposed to the airstream. The trip and reset temperature are different depending on unit model number. This information is printed on the side of the limit. Generally, the limit is factory set to trip when discharge air temperature rises above 130 F to 155 F and automatically reset when discharge air temperature drops below 95 F to 120 F. I - Secondary Limit S20 460V and 575V electric heat units are equipped with bimetal non-resettable secondary limits in lieu of the F5 fuses used in all other ECB24 units. S20 limits are connected to two of the three legs. If either limit opens, the heating elements are sequenced off. The trip and reset temperature may be different depending on unit model number. This information is printed on the side of the limit. Generally, the limit is factory set to trip when discharge air temperature rises above 200 F and cannot be reset once opened. Page 22

23 J - Heating Elements Optional ECB24 electric heat is composed of helix wound nichrome bare heating elements which are exposed directly to the airstream. Heating elements are energized directly by the heat sequencing relays located on sequence controller A36. The relays on the sequence controller are energized by blower control board A45. Control board A45 controls how many stages of heat to energize. Once energized, heat transfer is instantaneous. Each element is energized independently by a separate sequencer control (A36) relay and is protected by safety limits. Heating elements used in ECB24 series units are listed in table 10. DELTA HEATING ELEMENT ARRANGEMENT 208/240V HEATERS L1 L2 L3 Single phase Heaters Small kw units use a single heating element connected to line voltage by way of a sequencer control (A36) relay and safety limits. All other units use multiple small kw heating elements connected in parallel. The kw rating of each element is added together to reach the total kw rating of the unit. Three-phase heaters Three-phase heaters use three heating elements connected in a Delta arrangement and each element is connected in series with a set of relay contacts. This arrangement allows each side of the Delta to be energized independently. See Figure 30. DELTA HEATING ELEMENT ARRANGEMENT 460V AND 575V HEATERS L1 L2 L3 F5 F5 F5 S20 S20 HTR1 HTR3 K K HE(1) HE(3) HE(1) HE(3) HE(2) HTR2 Phase Volts = Line Volts Phase Current x 3 Line Current FIGURE 29 TABLE 10 ECB24 Heating Elements HE(2) K Phase Volts = Line Volts Phase Current x 3 Line Current FIGURE 30 Unit Total Watts Elements Number of Elements Config. Watts Each ECB24-2.5P 2500@24OV ECB24-5P 5000@240V ECB24-6P 6000@240V 2 Parallel 3000 ECB24-7P 7000@240V 2 Parallel 3500 ECB24-8P 8000@240V 2 Parallel 4000 ECB24-10P 10,000@240V 2 Parallel 5000 ECB P 12,500@240V 3 Parallel 4167 ECB24-15P 15,000@240V 3 Parallel 5000 ECB24-20P 20,000@240V 4 Parallel 5000 ECB24-25P 25,000@240V 6 Parallel 4167 ECB24-30P 30,000@240V 6 Parallel 5000 ECB24-5Y 5000@240V 3 Delta 1667 ECB24-7.5Y 7500@240V 3 Delta 2500 ECB24-10Y 10,000@240V 3 Delta 3333 ECB24-15Y 15,000@240V 3 Delta 5000 ECB24-20Y 20,000@240V 6 Delta 3333 ECB24-25Y 25,000@240V 6 Delta 4167 ECB24-10G 10,000@480V 3 Delta 3333 ECB24-15G 15,000@480V 3 Delta 5000 ECB24-20G 20,000@480V 3 Delta 6667 ECB24-25G 25,000@480V 3 Delta 8333 ECB24-15J 15,000@600V 3 Delta 5000 ECB24-20J 20,000@600V 3 Delta 6667 ECB24-25J 25,000@600V 3 Delta 8333 Page 23