35
6.3.
Third Party Digital Input to Control Dehumidification
1. Go to
SETUP > INSTALL
. Set
Configuration ID1
, position
1
to
H
for Humiditrol option. Follow the wizard until
sensor type option is prompted and select
REHEAT DI4
.
2. An alternate method is to
Go
to
SETTINGS > RTU OPTIONS > DEHUMIDIFIER.
For
SENSOR TYPE,
select
REHEAT DI4.
This method will
only work if
Configuration ID 1,
position
1
is set correctly.
REHEAT DI4 is digital input 4 that is for Humiditrol or third-party products (see figure 7).
USE 24 VAC (R) FROM ANY OF
THE AVAILABLE: P299-2, -5, OR -7
7
10
D
8
9
R
DI-4
C
Figure 7. REHEAT DI14 Diagram
6.4.
Outside Air For Dehumidification
The M3 unit controller has an option that allows “fresh air tempering control” heated outside air to be used to dehumidify
when outside air temperature is low.
When parameter 313 is set to options 1 3
(see table 22), outside air will be used for
dehumidification instead of the compressor.
Fresh Air Heating starts when the outside air temperature is <= the set point
parameter 168.
Additional conditions for operation apply (see table 22).
Table 22. Outside Air for Dehumidification Conditions
Parameter 313
(Options)
Outside Air Dehumidification Conditions
0
Disabled.
1
Allowed, must be occupied.
2
Allowed, blower must be energized and in occupied mode.
3
Allowed. No conditions apply.
The M3 unit controller will use the gas or electric heat to temper discharge air and the outside air will be used to dehumidify
(when there is a dehumidification demand and outside air is cool). Adjust the following settings:
Parameter 166 - Fresh Air Heating Control Reheat Outdoor Air Temperature set point default setting of 45.0°F.
Parameter 167 - Fresh Air Heating Control Reheat Damper position default setting is 40%.
Parameter 168 - Fresh Air Heating Control Reheat Set Point default setting is 40.0°F)
Fresh Air Reheat Mode can be adjusted also through the user interface.
NOTE
: The below menu option is only available if a economizer or motorized outside air damper is installed and enabled
using
Configuration ID 1
, position
2
. That position needs to be set to one of these options (
M
,
T
,
G
,
S
or
D)
.
Go to
SETUP > TEST & BALANCE > DAMPER >
(
NOTE
: There several settings to select in this path before
reaching the desired setting )
FRESH AIR HEATING ENABLE FAH
=
YES
or
NO
.
Parameter 313 (FAH REHEAT MODE) can also be used along with parameter 105 (DEHUMID MODE) options 2 through
7. Do not use option 1.
6.5.
Selecting Minimum Low and Minimum High Damper Positions
The following tables reference minimum damper positions which have two possible values for units with MSAV blower
option, parameter 9 = MIN DAMPER LOW BLWR or parameter 132 = MIN DAMPER POSITIO
N
. Which minimum
damper position is used depends on a mid-point calculation and actual blower speed.
The mid-point speed is determined
as
(Min Cool CFM + Max Cool CFM)/2 from those available for the number of
compressors installed. Then if actual blower speed is < mid-point parameter 9 is used, otherwise parameter 132 used.
