49
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 re-
moval from the cooled air.
2. Cool to Dehumidify
The cool to dehumidify selection tells the system to operate the compres-
sor, 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 hu-
midity satisfaction. When overcooling must occur, the dehumidify set-
point is adjusted upward 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 setpoint of 75
_
F/24
_
C and a dehumidify setpoint
of 62%. This dehumidify setpoint change is internal to the Thermidistat
Control and is not shown on the display.