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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
variable
−
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 satisfaction. When overcooling must occur, the dehumidify
