Carrier Performance Edger Thermidistat Control TP-NRH01-B Installation Instructions Manual page 52

Dehumidification
Dehumidification is done only during cooling. Depending on type of equipment
used, compressor speed, blower speed, setpoint adjustment, and equipment cycling
are modified to provide added dehumidification. A dehumidification setpoint
(separate from humidification setpoint) is available to the homeowner. It can range
from 46% to 66% relative humidity. When actual humidity is higher than setpoint, a
dehumidification demand exists. The Thermidistat Control responds by activating
the dry contact (when enabled in Option 19). It may also control the compressor
and blower, depending on equipment type and dehumidify selection choice. The 3
available selections are described below. A mandatory 5 minute blower off delay
will be enforced if there has been a call for dehumidification during a cooling call.
The amount of extra dehumidification available is very dependent on the type of
equipment in the home. Without a variable- speed blower, the system's ability to
adjust dehumidification is very limited.
1. Normal Dehumidify Operation
When normal dehumidify is selected, the compressor will not turn on
without a cooling demand. If dehumidify demand exists while cooling, dry
contact will also be active (24VAC removed). This output commands vari-
able- speed blowers to reduce their airflow, which improves water removal
from the cooled air.
2. Cool to Dehumidify
The cool to dehumidify selection tells the system to operate the compressor,
within limits, when there is a dehumidify demand even if there is no cooling
demand. The limits are that the system may overcool up to 3_, but no more,
while attempting to satisfy a dehumidify demand. Within this 3_ range,
there is an additional balance between overcooling and humidity satisfac-
tion. When overcooling must occur, the dehumidify setpoint is adjusted up-
ward by 2% per degree of overcooling. For example, a cooling setpoint of
76_F/24_C and a dehumidify setpoint of 60% is equivalent to a cooling set-
point of 75_F/24_C and a dehumidify setpoint of 62%. This dehumidify set-
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