DEZ
S
ERIES
1000
I
NSTALLATION
,
O
PERATION AND
M
AINTENANCE
M
ANUAL
11
Reactivation Air
Discharge Temperature
Process Control
Humidity Setpoint
Process Control
Humidity Actual
PI
Reactivation Heater
Temperature Actual
PI
Reactivation
Heater Setpoint
Reactivation
Heat Output
PI
Reactivation Air
Discharge Setpoint
Minimum
Requires:
A cold surface temperature sensor (or
temperature sensor at coldest point in room),
an ambient dewpoint temperature transmitter,
and an E² microprocessor controller.
How it Works:
The controller determines the amount of
reactivation energy required to maintain
dewpoint temperature. The controller
compares the cold surface temperature to the
ambient dewpoint temperature and develops a
control output. The dehumidifier runs
continuously and the controller continuously
adjusts reactivation heat in response to load
changes. The dehumidifier maintains the
space dewpoint at 5 °F (adjustable) less than
the cold surface temperature.
In Remote mode the process blower runs
continuously and the dehumidifier responds to
a customer-supplied start/stop signal.
3.4.5 Proportional Reactivation Controls
(H-Trac or Dew-Trac)
If the system is configured for H-Trac or Dew-Trac
reactivation control, the unit proportionally controls
humidity. When the Humidity PI loop output
exceeds 0%, the reactivation heater and
reactivation blower turn on. The controller
calculates PI loop outputs for humidity,
reactivation discharge air temperature and
reactivation heater temperature (see Figure 4).
As each of these PI loop outputs modulate, the
controller selects the lower PI loop output and
uses that output to control the reactivation heater.
Note: This methodology prevents overheating of
the desiccant, which would result in diminished
drying performance. Once the Humidity PI loop
output drops to 0% for the “Reactivation Idle” time,
the Energy Savings Feature shuts off reactivation
but the process blower continues to operate,
ensuring accurate humidity measurement and
control, even when dehumidification isn’t required.
Figure 4 - Proportional (Trac) Control Diagram
3.5 Control Panel
The control panel on the unit will vary depending on
whether the unit is equipped with a standard Watlow
controller or an optional E
2
microprocessor controller.
E
2
-equipped units typically have a single red Fault
Status light that notifies the operator that a fault has
occurred; the actual fault is indicated on a display
connected to the E
2
. Units without an E
2
controller can
have one or more indicators, each indicating a
different fault or status.
Units also have a three-way rotary switch labeled
ON/OFF/AUTO or LOCAL/OFF/REMOTE as
described in section 3.5.1. Two representative
control/Indicator layouts are illustrated in Figure 5 and
Figure 6.
