Troubleshooting guide

ManualsBrandsCarrier ManualsDomestic Appliances59MN7A

-1- Replaces: NEW Form: 59MN7A-01T

9-11

Variable Speed, Modulating

Electronic Condensing

Four-Way Multipoise Gas Furnace

59MN7A Series 100

TROUBLESHOOTING GUIDE

INDEX

PAGE

Safety Considerations ................................................................................. 1

Instructions .................................................................................................. 1

Example ...................................................................................................... 2

General ........................................................................................................ 2

Sequence of Operation ............................................................................... 2

Communicating Control and Modulating Heating ........................... 2

Single-Stage Thermostat and Modulating Heating (Adaptive

Mode) ......................................................................................... 3

Two-Stage Thermostat and Two-Stage Minimum/Maximum

Heating ....................................................................................... 4

Two-Stage Thermostat and Two-Stage Intermediate/Maximum

Heating ....................................................................................... 4

Cooling Mode .................................................................................... 5

Single-Speed Cooling ........................................................................ 5

Single-Stage Thermostat and Two-Speed Cooling (Adaptive

Mode) ......................................................................................... 5

Two-Stage Thermostat and Two-Speed Cooling ............................. 6

Dehumidification Mode ..................................................................... 6

Super-Dehumidify Mode ................................................................... 6

Continuous-Blower Mode ................................................................. 6

Heat Pump Defrost ............................................................................. 7

Component Test ................................................................................. 7

Service/Status Code Instructions ............................................................... 8

Start Here .................................................................................................. 10

Rapid Flashing AMBER LED ................................................................. 11

Improper Cooling Air Flow ..................................................................... 12

Minimum and/or Maximum Heat Temperature Rise Too Low ............. 14

Status Code 11 - No Previous Code ......................................................... 15

Status Code 12 - Blower On After Power Up ......................................... 15

Status Code 13 - Limit Circuit Lockout .................................................. 16

Status Code 14 - Ignition Lockout ........................................................... 17

Status Code 15 - Blower Motor Lockout ................................................. 17

Status Code 21 - Gas Heating Lockout .................................................... 17

Status Code 22 - Abnormal Flame-Proving Signal ................................. 18

Status Code 23 - Pressure Switch Did Not Open .................................... 18

Status Code 24 - Secondary Voltage Fuse Is Open ................................. 19

Status Code 25 - Model Selection or Setup Error ................................... 21

Status Code 31 - Medium Pressure Switch, High Pressure Switch, or

PSR Relay did not Close or Reopened ............................................ 22

Status Code 32 - Low Pressure Switch Did Not Close or Reopened ..... 25

Status Code 33 - Limit Circuit Fault ........................................................ 27

Status Code 34 - Ignition-Proving Fault .................................................. 29

Status Code 35 - Gas Valve Fault ............................................................ 31

Status Code 41 - Blower Motor Fault ...................................................... 33

Status Code 42 - Inducer Motor Fault ..................................................... 35

Status Code 43 - Low or Medium Pressure Switch Open While

Medium or High Pressure Switch Is Closed ................................... 37

Status Code 45 – Control Circuitry Lockout ........................................... 38

Cleanup and Start-Up Instructions ........................................................... 38

APPENDIX A - Board Layout & Wiring Schematic ............................. 39

APPENDIX B - ECM Blower Motor Description & Operation ............ 41

APPENDIX C - Pressure Check Diagram ............................................... 43

APPENDIX D - Static Pressure Reading Location Diagrams ................ 44

APPENDIX E - Quick Reference Information ....................................... 46

APPENDIX F - Furnace Staging Algorithm ........................................... 47

SAFETY CONSIDERATIONS

Installing and servicing heating equipment can be hazardous due to

gas and electrical components. Only trained and qualified personnel

should install, repair, or service heating equipment.

Untrained personnel can perform basic maintenance functions such as

cleaning coils, or cleaning and replacing filters. All other operations

should be performed by trained service personnel. When working on

heating equipment, observe precautions in literature, on tags, and on

labels attached to or shipped with the unit, and other safety

precautions that may apply.

Follow all safety codes. In the United States, follow all safety codes

including the National Fuel Gas Code (NFGC) NFPA 54-2006/ANSI

Z223.1-2006. In Canada, refer to the National Standard of Canada

Natural Gas and Propane Installation Codes (NSCNGPIC), CSA

B149.1-05.

Wear safety glasses and work gloves. Have a fire extinguisher

available during start-up, adjustment procedures, and service calls.

Recognize safety information. This is the safety-alert symbol .

When you see this symbol on the furnace and in instructions or

manuals, be alert to the potential for personal injury.

Understand the signal words DANGER, WARNING, and CAUTION,

and NOTE. The words DANGER, WARNING, and CAUTION are

used with the safety-alert symbol. DANGER identifies the most

serious hazards which will result in severe personal injury or death.

WARNING signifies hazards which could result in personal injury or

death. CAUTION is used to identify unsafe practices which may

result in minor personal injury, or product and property damage.

NOTE is used to highlight suggestions which will result in enhanced

installation, reliability, or operation.

INSTRUCTIONS

This guide uses your expertise and observations to lead you to the

trouble spot as efficiently as possible. This is only intended as a guide

and should not be used blindly. Your experience and expertise are of

high value when troubleshooting this unit. Do not disregard all of

your instincts.

Summary of content (48 pages)

PAGE 1
Variable Speed, Modulating Electronic Condensing Four-Way Multipoise Gas Furnace 59MN7A Series 100 TROUBLESHOOTING GUIDE APPENDIX B - ECM Blower Motor Description & Operation ............ 41 APPENDIX C - Pressure Check Diagram............................................... 43 APPENDIX D - Static Pressure Reading Location Diagrams ................ 44 APPENDIX E - Quick Reference Information ....................................... 46 APPENDIX F - Furnace Staging Algorithm ....................................
PAGE 2
If the ACTION is a question (a question will have a number in the YES or NO column), answer it YES or NO. If the answer is YES, go to the step indicated in the YES column. If the answer is NO, go to the step indicated in the NO column. The modulating furnace control was designed with diagnostic capabilities built in. An AMBER LED is used to flash a status code which will lead you to one of the sections as listed in the Index.
PAGE 3
evaluation is then used to determine the required RPM necessary to operate the inducer motor during prepurge, the first 45 seconds of intermediate-heat mode, or any modulating rate that the furnace will transition to after the blower on-delay is completed. When a communicating control is used, the furnace will modulate through its full operation range, or can be limited via the minimum and maximum cfm configurations.
PAGE 4
7. closing the thermostat R to W1 circuit. Closing the thermostat R to W1-and-W2 circuits always causes maximum-heat operation, regardless of the setting of the minimum-heat only switch.
PAGE 5
motor BLWM will continue operating at cooling airflow for an additional 90 seconds. Jumper Y/Y2 to DHUM to reduce the cooling off-delay to 5 seconds. (See Fig. 1.) changed to intermediate-heat. When the inducer motor speed gets within 15% of the required intermediate-heat RPM the furnace control CPU will start a 5 second blower airflow change delay. After the 5 second blower airflow change delay is completed the blower airflow will transition to intermediate-heat airflow. 2.
PAGE 6
Note: The air conditioning relay disable jumper ACRDJ must be disconnected to allow thermostat control of the outdoor unit staging. (See Fig. 1.) The thermostat closes the R to G-and-Y1 circuits for lowcooling or closes the R to G-and-Y1-and-Y2 circuits for highcooling. The R to Y1 circuit starts the outdoor unit on lowcooling speed, and the R to G-and-Y1 circuit starts the furnace blower motor BLWM at low-cooling airflow which is the true on-board CF selection as shown in Table 1.
PAGE 7
motor BLWM is operating. The furnace control CPU will shift the continuous-blower airflow from the factory setting to the next highest CF selection airflow as shown in Table 1. Momentarily turning off the FAN switch again at the thermostat will shift the continuous-blower airflow up one more increment. If you repeat this procedure enough you will eventually shift the continuous-blower airflow to the lowest CF selection as shown in Table 1.
PAGE 8
SERVICE/STATUS CODE INSTRUCTIONS If status code recall is needed disconnect the “R” thermostat lead, reset power, and put setup switch “SW1-1” in the ON position. To clear the status code history put setup switch “SW1-1” in the ON position and jumper thermostat terminals “R”, “W/W1”, and “Y/Y2” simultaneously until status code #11 is flashed. LED CODE CONTINUOUS OFF CONTINUOUS ON RAPID FLASHING - STATUS Check for 115 VAC at L1 and L2, and 24 VAC at SEC-1 and SEC-2. Control has 24 VAC power.
PAGE 9
33 34 35 41 42 43 45 LIMIT CIRCUIT FAULT – Indicates the limit, or flame rollout is open or the furnace is operating in maximum-heat only mode due to 2 successive limit trips while operating at any rate less than or equal to 71% of maximum rate. Blower will run at intermediate heat airflow for 4 minutes or until open switch remakes whichever is longer. If open longer than 3 minutes, code changes to lockout #13. If open less than 3 minutes status code #33 continues to flash until blower shuts off.
PAGE 10
START HERE - If a problem exists, the service technician should always begin troubleshooting here. Special Note: All voltmeters are not the same - your voltage readings will vary. This applies to the entire content of this troubleshooting manual. They are not absolute values. Correct 115-VAC VOLTAGE, CURRENT, and power MEASUREMENTS CANNOT BE TAKEN ON MODULATING FURNACES UNLESS USING A TRUE rms METER. STEP 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. 19. 20. 21. 22. 23. 24. 25.
PAGE 11
STEP 26. 27. 28. 29. 30. 31. ACTION Is 115-vac across the transformer leads? Replace the transformer. Is 24-vac across W/W1 and on the modulating furnace control? You will not be able to check for voltage across W/W1 and COM-24V if the furnace is connected to a User Interface at the ABCD connector. Go to step 29. You have a defective thermostat, or a break in wiring between thermostat and furnace. Fix problem. Disconnect all thermostat leads from the thermostat terminal block and jumper R to W/W1.
PAGE 12
IMPROPER COOLING AIR FLOW - Generally, this indicates the Y/Y2 thermostat lead is not properly connected. If User Interface is connected to ABCD connector then the wrong size outdoor unit could be configured in the User Interface. STEP 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. 19. 20. 21. 22. 23. 24. 25. 26. 27. 28. ACTION Remove blower door and depress door switch. Use a piece of tape to hold switch closed. Set thermostat to call for cooling.
PAGE 13
Table 2 – Cooling Tonnage vs. Airflow (CFM) AIR CONDITIONING TONS (12,000 BTU/HR) 1-1/2 2 2-1/2 3 3-1/2 4 5 6 AIRFLOW (CFM) 525 700 875 1050 1225 1400 1750 2100 060, & 3.5T-080 MODEL X X X X X 5T-080 & 100 MODEL 120 MODEL X X X X X X X X X X X X X AIR CONDITIONING (A/C) OR CONTINUOUS-FAN (CF) AIRFLOW SELECTION CHART BASED ON 350 CFM/TON (SETUP SWITCH SW1-5 OFF, SW4-3 OFF) SETUP SWITCH SW2 OR SW3 POSITIONS MODEL SIZE 060,3.5T-080 DEF. 5252 700 875 10501 1225 1225 1225 5T-080, 100 DEF.
PAGE 14
MINIMUM AND/OR MAXIMUM HEAT TEMPERATURE RISE TOO LOW - Generally, this indicates the furnace is extremely underfired. STEP 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. ACTION Remove the blower door. Disconnect User Interface ABCD connector (if used) or the R thermostat lead (if used) from the furnace control board. If setup switch SW4-2 is ON then turn it OFF. Depress the door switch. Use piece of tape to hold it closed. Put setup switch SW1-2 into the ON position.
PAGE 15
Status Code 11 NO PREVIOUS CODE - Stored status codes are erased after 72 hours or can be cleared by jumpering R, W/W1, and Y/Y2 thermostat leads while setup switch SW1-1 is ON. Run system through a heating or cooling cycle to check system. This usually indicates one of the following: - The status history has been cleared and setup switch SW1-1 is in the ON position. - Component test was successfully completed and setup switch SW1-6 is in the ON position. STEP ACTION 1.
PAGE 16
STEP 23. 24. 25. 26. ACTION The call for heat was probably satisfied during the blower on-delay period, or power to the furnace was probably interrupted during a call for heat. This is normal operation. Go to the page number indicated in Index for the CLEANUP AND STARTUP INSTRUCTIONS. Disconnect VIOLET wire from the medium pressure switch MPS. Does the furnace still alternately cycle induced draft motor IDM and blower motor BLWM as described in Step 4.
PAGE 17
Status Code 14 IGNITION LOCKOUT - This status code indicates the furnace failed to ignite gas and/or prove flame in 4 attempts. The modulating furnace control will auto-reset in 3 hours. If the inducer motor is not running during lockout refer to status code 34. If the inducer motor is running at full speed during lockout this indicates that flame sense was lost 3 times within 60 minutes of cumulative gas valve operating time after the gas valve was already ON for 70 seconds.
PAGE 18
Status Code 22 ABNORMAL FLAME-PROVING SIGNAL - This status code indicates the flame signal was sensed while gas valve GV was deenergized. The inducer will run until the fault is cleared. STEP ACTION YES NO GO TO 1. Turn off gas to the furnace by shutting off the external manual shut-off valve. 2 2. Does status code 22 stop flashing? 3 4 3. Replace the gas valve. 8 4. Disconnect wire from the flame-proving sensor electrode FSE. 8 5. Does status code 22 stop flashing? 6 7 6.
PAGE 19
Status Code 24 SECONDARY VOLTAGE FUSE IS OPEN - Indicates fuse is open and there is a short in low-voltage wiring. STEP ACTION YES 1. Turn power off and remove the blower door. 2. Is secondary voltage fuse blown? Check continuity to make sure. 5 3. Replace modulating furnace control. 4. Replace secondary voltage fuse if necessary then go to page number indicated in Index for CLEANUP AND START-UP INSTRUCTIONS. 5.
PAGE 20
STEP 36. 37. 38. 39. 40. 41. 42. ACTION Does status code 34 flash? If not, status code 24 should occur when BLUE wire is energized. Turn power off and disconnect PL1 from modulating furnace control. Do you have continuity between the BLUE wire and chassis ground? Do you have continuity between the GRAY wire connected to both the medium and high pressure switches and chassis ground? You have a short circuit in the GRAY wire to the medium and high pressure switches.
PAGE 21
Status Code 25 MODEL SELECTION OR SETUP ERROR – If status code 25 only flashes 4 times on power-up the modulating furnace control is missing its model plug (PL4) and is defaulting to the model selection stored in memory. If status code 25 flashes continuously it could indicate any of the following: 1. Model plug (PL4) is missing and there is no valid model stored in permanent memory. This will happen if you forget to install the model plug (PL4) on a service replacement board. 2.
PAGE 22
Status Code 31 MEDIUM PRESSURE SWITCH, HIGH PRESSURE SWITCH, OR PSR RELAY DID NOT CLOSE OR REOPENED - This status code can occur under the scenarios shown below. Keep in mind that whenever the modulating furnace control shuts unit down, gas remains off or shuts off immediately, inducer continues running for 15 seconds, and if the blower is running, it remains running at minimum heat airflow or reduces to minimum heat airflow for the selected off-delay.
PAGE 23
down. After the blower off-delay is completed the modulating furnace control will stop displaying status code 31 and if there is a call for heat, begin a new heating cycle. 4. HIGH TO MEDIUM RANGE INPUT TRANSITION - If the medium pressure switch MPS opens while transitioning to a medium range input, the modulating furnace control ramps inducer RPM up until the medium pressure switch MPS remakes. When the medium pressure switch MPS remakes the modulating furnace control continues heating cycle.
PAGE 24
STEP 33. 34. 35. 36. 37. 38. 39. 40. 41. 42. 43. 44. 45. 46. 47. 48. 49. 50. 51. 52. 53. 54. 55. 56. 57. 58. 59. 60. 61. 62. 63. ACTION Does the inducer wheel turn freely? Continue to observe furnace operation for 20 minutes or until status code starts flashing. Does status code 31 flash? Does a different status code flash? Turn power off and disconnect jumper wire across R and W/W1 thermostat terminals. Connect 1 side of slope manometer with a tee to collector box pressure tap.
PAGE 25
Status Code 32 LOW PRESSURE SWITCH DID NOT CLOSE OR REOPENED - This status code can occur as a result of the low pressure switch LPS not making or the low gas pressure switch LGPS opening. Regardless of which switch is open, the modulating furnace control will operate under the scenarios shown below. Keep in mind that whenever the modulating furnace control shuts unit down, gas remains off or shuts off immediately and inducer continues running for 15 seconds.
PAGE 26
STEP 34. 35. 36. 37. 38. 39. 40. 41. 42. 43. 44. 45. 46. 47. 48. 49. 50. 51. 52. 53. 54. 55. ACTION You have excessive restriction in combustion-air or vent pipe. Also check for proper vent sizing for installation. Continue to observe furnace operation for 20 minutes or until status code starts flashing. Does status code 32 flash? Does a different status code flash? Turn power off and disconnect jumper wire across R and W/W1 thermostat terminals.
PAGE 27
Status Code 33 LIMIT CIRCUIT FAULT - This status code indicates the limit, flame rollout switch is open, or the furnace is operating in maximum-heat only mode due to 2 successive limit trips while operating at any rate < 71% of maximum rate. Blower will run for 4 minutes at intermediate heat airflow or until the open switch remakes whichever is longer. If open longer than 3 minutes, code changes to lockout #13. If open less than 3 minutes status code #33 continues to flash until blower shuts off.
PAGE 28
STEP 40. 41. 42. 43. 44. 45. 46. 47. 48. 49. 50. 51. 52. 53. 54. 55. 56. 57. 58. 59. 60. 61. 62. 63. 64. 65. 66. 67. 68. 69. 70. 71. 72. 73. 74. ACTION Remove tape from door switch, turn power off at main disconnect, and remove jumper across R and W/W1. Is the blower wheel firmly mounted on motor shaft? Does the model plug PL4 match the part number specified on the Rating Plate? Replace model plug. Clean or replace filter if necessary, then recycle furnace after limit resets.
PAGE 29
Status Code 34 IGNITION-PROVING FAULT - This status code indicates flame was not sensed during trial for ignition period. The control will repeat ignition sequence 3 more times before going to status code 14 - IGNITION LOCKOUT. This status code can also indicate flame signal was lost during steady-state operation. STEP ACTION YES NO GO TO 1. Shut the power off, remove the blower door, and disconnect User Interface ABCD connector 2 (if used) or the R thermostat lead (if used) from the furnace control board.
PAGE 30
STEP 32. 33. 34. 35. 36. 37. 38. 39. 40. 41. 42. 43. 44. 45. 46. 47. 48. 49. 50. 51. ACTION Clean flame sensor with fine steel wool and make sure it is properly positioned then recheck current. Current is typically 4.0 to 6.0 microamps. Is current near typical value? Replace electrode. Will main burners ignite and stay on? Do you have burner pulsation’s? Check the following: - Ensure there are no flue gas leaks in the vestibule. - Ensure vent and combustion-air pipes are not reversed.
PAGE 31
Status Code 35 GAS VALVE FAULT - This status code indicates that the modulating gas valve failed to respond to a command from the modulating furnace control or power to the gas valve electronics was interrupted. On every cycle after the medium pressure switch MPS makes the modulating furnace control sends a PWM (pulse width modulation) command to the gas valve GV for a duration of 1 second. Following this the gas valve GV responds back with the PWM command it received for a duration of 1 second.
PAGE 32
STEP 25. 26. 27. 28. 29. 30. 31. 32. 33. 34. 35. 36. 37. 38. 39. 40. 41. 42. 43. ACTION Do you have continuity between PL8-2 and PL17-2? YES 13 Note: The terminals in PL8 can be permanently damaged if the voltmeter probe is jammed into the terminal end of the connector. Use caution when checking. You have an open wire or a bad terminal on the YELLOW wire between connector PL8 and PL17. Repair or replace the wire harness. Put setup switch SW1-6 in the OFF position.
PAGE 33
Status Code 41 BLOWER MOTOR FAULT - This status code indicates the blower failed to reach 250 RPM or the blower failed to communicate to the modulating furnace control within 30 seconds after being turned ON or within 10 seconds during steady-state operation. STEP ACTION YES NO GO TO 1. Shut the power off, remove the blower door and disconnect User Interface ABCD connector 2 (if used) or the R thermostat lead (if used) from the furnace control board. 2. Turn the power on and depress the door switch.
PAGE 34
STEP 28. ACTION Check the blower motor serial output signal. To do this disconnect PL3 from the furnace control and connect a DC voltmeter across terminals PL3-4 (+) and PL3-2 (-) on the modulating furnace control. The voltage should be near 0-vdc but it will fluctuate briefly several times a second. If you have an analog voltmeter the needle will briefly go high several times a second.
PAGE 35
STEP 46. 47. 48. 49. 50. ACTION When blower control module is completely detached from blower motor, verify with standard ohmmeter that the resistance from each motor lead in motor plug to unpainted motor end plate is greater than 100k ohms. Then verify motor windings are not shorted or open by measuring resistance between each combination of pins in motor plug (there are three different combinations, pin 1-2, pin 2-3, and pin 1-3). Resistance should be approximately equal across each combination of pins.
PAGE 36
23. 24. 25. 26. 27. 28. 29. 30. 31. 32. 33. 34. 35. 36. 37. 38. 39. Reconnect PL16 to the inducer motor and put setup switch SW1-6 in the OFF position. Does inducer wheel turn freely? Replace the inducer motor control (if you have a 2 piece design) or the inducer motor assembly. Does the inducer wheel rub against inducer housing? Does status code 42 flash within 20 seconds after a call for heat? Turn power off and disconnect jumper from the R and W/W1 thermostat terminals.
PAGE 37
STEP 61. 62. 63. 64. 65. 66. 67. 68. ACTION Does a different status code flash? Is there any frost build-up on combustion-air inlet? The problem is caused by reversed vent and combustion-air pipes or some other moist air entering combustion-air pipe. You have excessive restriction in combustion-air or vent pipe. Also check for proper vent sizing for installation. While the unit is operating in minimum heat jumper R and W2. Observe the operation of the furnace for the next 8 minutes or until fault occurs.
PAGE 38
STEP 20. 21. 22. 23. 24. 25. ACTION Is 24-vac across GRAY wire on the medium pressure switch MPS and COM-24V on modulating furnace control? You have an open wire or bad terminal on the GRAY wire from the high pressure switch HPS to the medium pressure switch MPS. Repair it or replace the harness.
PAGE 39
APPENDIX A BOARD LAYOUT AND WIRING SCHEMATICS COMMUNICATION CONNECTOR MODEL PLUG CONNECTOR CONTINUOUS FAN (CF) AIRFLOW SETUP SWITCHES OUTDOOR AIR TEMP CONNECTOR SW4 SETUP SWITCHES SW1 SETUP SWITCHES AND BLOWER OFFDELAY AIR CONDITIONING (A/C) AIRFLOW SETUP SWITCHES HUMIDIFIER TERMINAL (24-VAC 0.5 AMP MAX.
PAGE 40
Fig.
PAGE 41
APPENDIX B ECM BLOWER MOTOR DESCRIPTION & OPERATION The Regal-Beloit Electronically Commutated Motor (ECM) shown in figure 3 is the newest generation of variable speed blower motors. This motor has all of the capabilities of the previous ECM blower motor but has internal memory storage which provides operational information to the manufacturer when the motor is returned. In addition this new design has improved reliability due to the consolidation of two circuit boards into one.
PAGE 42
Figure 3 – ECM Blower Motor - 42 -
PAGE 43
APPENDIX C PRESSURE CHECK DIAGRAM UNIT SIZE (BTUH) 60,000 (17.5” casing) 60,000 (21” casing) 80,000 100,000 120,000 PRESSURE SWITCH MAKE/BREAK POINTS HIGH PRESSURE SWITCH MEDIUM PRESSURE SWITCH Make Point Break Point Make Point Break Point 0.70 in. wc +/1.05 in. wc +/0.85 in. wc max 1.21 in.wc max 0.05 0.06 0.85 in. wc +/1.29 in. wc +/1.00 in. wc max 1.46 in.wc max 0.05 0.07 0.85 in. wc +/1.40 in. wc +/1.00 in. wc max 1.58 in.wc max 0.05 0.08 0.93 in. wc +/1.40 in. wc +/1.08 in. wc max 1.58 in.wc max 0.
PAGE 44
APPENDIX D STATIC PRESSURE READING LOCATION DIAGRAMS Figure 5 – Upflow Total Static Pressure Reading Locations Figure 6 – Downflow Total Static Pressure Reading Locations - 44 -
PAGE 45
Figure 7 – Horizontal Right Total Static Pressure Reading Locations Tools Needed: 1. 2. Pitot Tube Incline Manometer/Magnahelic Example 1: Return ESP after Filter Supply ESP before Coil -----------------------------------------------------Total ESP 0.20 in.w.c. 0.40 in.w.c. --------------0.60 in.w.c. Example 2: Return ESP before Filter Filter Static Pressure Drop @ 2000 cfm 0.10 in.w.c.
PAGE 46
APPENDIX E QUICK REFERENCE INFORMATION UNIT SIZE (BTUH) 60,000 (17.5” casing) 60,000 (21” casing) 80,000 100,000 120,000 PRESSURE SWITCH MAKE/BREAK POINTS HIGH PRESSURE SWITCH MEDIUM PRESSURE SWITCH Make Point Break Point Make Point Break Point 0.70 in. wc +/1.05 in. wc +/0.85 in. wc max 1.21 in.wc max 0.05 0.06 0.85 in. wc +/1.29 in. wc +/1.00 in. wc max 1.46 in.wc max 0.05 0.07 0.85 in. wc +/1.40 in. wc +/1.00 in. wc max 1.58 in.wc max 0.05 0.08 0.93 in. wc +/1.40 in. wc +/1.08 in. wc max 1.58 in.
PAGE 47
APPENDIX F FURNACE STAGING ALGORITHM On initial thermostat call for heat after power-up, furnace staging algorithm will provide 45 seconds of intermediate heat followed by 19 minutes of minimum heat provided setup switches SW1-2 and SW4-2 are off. If call for heat still exists after operating for 45 seconds in intermediate heat and 19 minutes in minimum heat, the furnace will switch to maximum heat until the thermostat is satisfied.
PAGE 48
Using recorded Modulating rate (MOD%), time of operation at the Modulating rate (MODT), and Maximum Heat (MAXT) calculate the Heat Load (HLR) using: Thermostat is satisfied. HLR = (MOD% x MODT) + 65 + (100 x MAXT) MOD% = 40% Unit will start the next cycle in Intermediate Heat for 45 seconds followed by 19 minutes of operation at 40% rate before switching to Maximum Heat if the call for heat still exists.