Appendix E
Operation
This
This troubleshooting guide has shown that the blower does a calibration 20 sec at start of any operation of ICM. Note that blower calibration sequence is different when setup switch
If furnace is on a call for heat or cooling and duct static is too high, ICM tries to overcome external static pressure. If duct static is excessive, ICM RPM will be out of range and a Fault Code 44 will flash on circuit board. The ICM RPM range is 250 to 1300 RPM as stated in Fault Code 44 troubleshooting section. To check for excessive static pressure, use the following Air Delivery Curves and Duct Static Check Sheet later in this Appendix.
EXAMPLE: Furnace is a 100,000 Btuh input with a 5 ton blower cooling capacity. We measured total external static pressure (ESP) to be 0.4 in. wc in
EXAMPLE AIR DELIVERY CURVE Ð 060100
External Static Pressure (in. wc)
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0.8 | HEAT | |
Constant System | ||
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0.7 | Curves | |
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0.6 |
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0.5 |
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LOW | ||
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| HEAT |
0.4*
0.3
0.2 |
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0.1 |
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| 21⁄2 Ton |
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| 2 Ton |
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700 | 900 | 1100 | 1300 | 1500 | 1700 | 1900 | 2100 |
CFM
A98451
Use the dashed lines as guide lines. As you can see, the 0.4 in. wc total ESP is in the shaded area. The unit can deliver low heat, but as you follow the dashed guide lines, you see that they do not cross the
See Static Pressure Reading Location Diagrams later in this Appendix for proper static reading locations. When checking total ESP, you must have blower operation without a Fault Code 44 occurring. If you have a Fault Code 44 in cooling and your setting is at 5 tons, set A/C tonnage to 4 tons and see if the Fault Code 44 goes away. If it does not, set switches to 3 tons, and so on until the Fault Code 44 goes away.
NOTE: When adjusting airflow, you must either turn power off or terminate thermostat call after every airflow adjustment. Record all static readings on Duct Static Check Sheet.
Solutions:
1.Dirty filter.
2.Plugged evaporator coil.
3.
SPECIAL NOTE: In zoning applications, it is recommended that when zone controls are applied, duct system be designed for sum of the peaks plus 25% oversize to allow furnace to operate within its design parameters. Contact your distributor for further details.
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