Manual 2100-614K
Page 9 of 61
HUMIDITY REDUCTION OPTIONS
The MC4002 does not include an indoor humidity
sensor, and humidity reduction operation will require
additional equipment installation. The following two
methods are typically used with the MC4002 to reduce
humidity.
• A humidistat may be connected to the controller.
When a humidistat is connected to the MC4002,
it will be used to operate one wall mount in
heating and one wall mount in cooling for a
limited period of time when humidity levels are
above the humidistat setpoint. This method of
humidity control is referred to as synchronized
dehumidification. Two wall mount units must
be installed and operated using the MC4002.
When purchasing equipment to be used with this
humidity reduction method, it is important to have
electric heat installed in both units and both units
to have matching heating and cooling capacities.
• Another method of humidity control is when one
or both wall mount units are purchased with hot
gas reheat dehumidication coils installed (“D”
model option). A humidistat is connected directly
to each of the wall mount units that have the
hot gas reheat option. When the humidity level
rises above the humidistat setpoint, the unit will
operate in dehumidication mode. This method
of humidity control is referred to as hot gas reheat
dehumidification. One or two wall mount units can
be connected directly to humidistats when used
to reduce humidity levels. Each wall mount unit is
connected independently of the MC4002 controller
for hot gas reheat humidity reduction and will not
alternate using lead/lag operation when running
in dehumidication mode. Cooling and heating
operation will use lead/lag operation controlled
by the MC4002. When purchasing equipment to
be used with this humidity reduction method, it
is important that one or both wall mount units
include the “D” hot gas reheat dehumidication
option.
Synchronized Dehumidication Option
NOTE: This function is not available if controller is
configured for heat pump.
The standard wall mount air conditioning system can
be adapted to perform dehumidication control by
addition of a simple humidistat that closes-on-rise
and is connected to terminals H1 and H2 on the main
controller board. See Figure 1 for connection of the
humidistat. The recommended humidistat is Bard P/N
8403-038 (H600A 1014). Both HVAC units must be
equipped with electric heat for this sequence to work
properly.
Sequence of operation with default setpoints:
1. Temperature control always has priority over
dehumidication. If there is any stage of cooling
demand active, the dehumidication sequence is
locked out by the MC4002 logic.
FIGURE 1
Mechanical Humidistat Connection for "D" Dehumidication Models
C
D
R
C
D
R
C
D
R
MIS-4304
1.) SEPARATE HUMIDISTAT IS REQUIRED FOR "D" DEHUMIDIFICATION UNIT OPERATION.
LOW VOLTAGE TERMINAL STRIP CONNECTIONS PROVIDED IN UNIT INSTALLATION INSTRUCTIONS.
2.) TH, TS, CH, AND OLDER WA**/WH** MODELS DO NOT HAVE A "D" TERMINAL ON THE LOW VOLTAGE
MECHANICAL HUMIDISTAT CONNECTION FOR "D" DEHUMIDIFICATION MODELS
TERMINAL STRIP. MODELS THAT DO NOT HAVE THE "D" TERMINAL USE THE "W3" TERMINAL. REVIEW
"R" AND "DEH" TERMINALS.
INSTALL JUMPER BETWEEN
R
C
DEH
DEH
RED
YELLOW
YELLOW
RED
TERMINAL STRIP
VOLTAGE
PART #8403-038
HUMIDISTAT #1
PART #8403-038
HUMIDISTAT #2
UNIT #1 LOW
TERMINAL STRIP
VOLTAGE
PART #8403-047
HUMIDISTAT #1
UNIT #2 LOW
TERMINAL STRIP
NOTES:
C
R
VOLTAGE
UNIT #1 LOW
TERMINAL STRIP
VOLTAGE
PART #8403-047
NOTES:
HUMIDISTAT #2
UNIT #2 LOW
INSTALL JUMPER BETWEEN
DEH
LOW VOLTAGE TERMINAL STRIP CONNECTIONS PROVIDED IN UNIT INSTALLATION INSTRUCTIONS.
1.) SEPARATE HUMIDISTAT IS REQUIRED FOR "D" DEHUMIDIFICATION UNIT OPERATION.
2.) TH, TS, CH, AND OLDER WA**/WH** MODELS DO NOT HAVE A "D" TERMINAL ON THE LOW VOLTAGE
TERMINAL STRIP. MODELS THAT DO NOT HAVE THE "D" TERMINAL USE THE "W3" TERMINAL. REVIEW
ELECTRONIC HUMIDISTAT CONNECTION FOR "D" DEHUMIDIFICATION MODELS
MIS-4304A
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