Dehumidification Operation; Supermarket Reheat Operation Settings; Humiditrol Dehumidification Operation - (Humiditrol® Reheat) - Lennox PRODIGY2.0 Application Manual

6. Dehumidification Operation

Dehumidification mode is a combination of cooling to dehumidify and heating to maintain space temperature.
Supermarket reheat uses gas heat and Humiditrol
evaporator. A gas heat unit is required for Supermarket Reheat and a Humiditrol
Economizer operation is disabled during dehumidification operation except when dehumidification mode operation -
parameter 105, Option 1 is selected.
NOTE: Dehumidification operations as referenced here are not supported for Energence Ultra-High Efficiency
LCH/LGH036U-74U. See Ultra Dehumidification Operation on page 43.
6.1.

Supermarket Reheat Operation Settings

Go to SETTINGS > RTU OPTIONS > EDIT PARAMETER=105 (DEHUMID MODE)
Parameter 105 (Option 0) - No Reheat
Parameter 105 (Option 1) - Supermarket Reheat using de-humidistat (wired thermostat mode only)
Supermarket Reheat is allowed on gas/electric units only and not electric/electric units. A de-humidistat will bring on
first-stage cooling to dehumidify and a room thermostat will energize heating to maintain indoor temperature. To disable
free cooling in this mode, select economizer global mode (figure 5) but do not connect the global input (P297-9). An
optional de-humidistat is required. Refer to figure 5.
24 VAC POWER
R
C
G
W1
B
W2
Y1
A
Y2
OCP
TO PROVIDE DEHUMID SCHEME, USE S86
DEHUMIDISTAT AND K55 RELAY
Parameter 105 (Option 2) — Supermarket Reheat using Relative Humidity Sensor Control
A relative humidity sensor will bring on first-stage cooling based on the set point set with parameter 106 or from the L
Connection network. First-stage cooling will de-energize when relative humidity drops to parameter 106 minus
parameter 107. A wired thermostat or room sensor will energize heating to maintain indoor temperature.
An optional relative humidity sensor is required. Refer to figure 37.
Go to SETTINGS > RTU OPTION > EDIT PARAMETER = 106 (DEHUMID SETPOINT) and 107 (DEHUMID
DEADBAND) (see paragraph 6.3. for further details concerning dehumidification set point)
6.2. Humiditrol Dehumidification Operation — (Humiditrol
Go to SETTINGS > RTU OPTIONS > EDIT PARAMETER = 105 (DEHUMID MODE)
A relative humidity sensor reading above set point will energize first-stage compressor(s) and hot gas will be routed to
the reheat coil based on the set point set with parameter 106 or from the L Connection network. The following options
show additional conditions which must be met before reheat will be energized:
Humiditrol dehumidification will de-energize when the relative humidity drops to parameter 106 minus parameter 107.
An optional relative humidity sensor is required. See figure 37.
TO M3 THERMOSTAT INPUTS
TO R
2
7
TO G
K55-1
S86
5
TO Y1
ALL OTHER THERMOSTAT
SIGNALS REMAIN CONNECTED
AS SHOWN ON THE RIGHT.
Figure 5. Dehumidification Diagram (Parameter 105, Option 1)
®
units route hot discharge gas to a reheat coil downstream of the
IMPORTANT
J297A
1
R
2
C
B
G 3
W1 4
5
W2
Y1 6
Y2 7
OCP 8
C
9
10
33
®
unit is required for Humiditrol
A55
P297
®
Reheat)
®
Reheat.