P707
INSTALLATION
P707
AND OPERATION
INSTRUCTIONS
Part Number P707-MDEH1
SAFETY CONSIDERATIONS
Installing, starting up, and servicing equipment can be hazardous due to system pressures, electrical components and
equipment location (roofs, elevated structures, etc.). Only
trained, qualified installers and service mechanics should
install, start up, and service this equipment.
When working on the equipment, observe precautions in the
literature and on tags, stickers, and labels attached to the
equipment.
Before installation, always check to be sure main power to
systems are OFF. Electrical shock can cause personal
injury or death.
GENERAL
The MDEH1 dehumidistat is used with Totaline SHR series
heat recovery ventilators. See Fig. 1. The dehumidistat is used
to control the indoor humidity level. High humidity is a major
Dehumidistat
cause of structure damage and IAQ problems such as mold
and mildew.
INSTALLATION
NOTE: For technical assistance, call 1-800-747-1762.
To install the dehumidistat, perform the following
procedure:
1. Determine the mounting location for the dehumidistat.
Location should be in an easily accessible area. Do not
locate where humidity sensor could be affected by
direct humidity sources.
2. All controls are low voltage. Use 22 to 26 gage fieldprovided wire.
3. Connect two wires to the DEHUM terminals on ventilator. See Fig. 2. Polarity does not matter. Either wire
can be connected to either terminal.
4. Run wire to mounting location. Do not run control
wire with power wiring. Interference from power wiring can cause changes to control signal.
Manufacturer reserves the right to
discontinue, or change at any time,
specifications or designs without notice
and without incurring obligations.
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Fig. 1 — Dehumidistat
REPLACEMENT COMPONENTS DIVISION LITERATURE NUMBER P707-3SI
© CARRIER CORPORATION 2004 2-04 REPLACES: New
PRINTED IN U.S.A. CATALOG NUMBER 570-330
5. The dehumidistat consists of two pieces, a mounting
plate and the cover. Remove cover from the mounting
plate. Pull wiring through the hole in the mounting
plate.
6. Connect wiring to the terminals on the mounting plate
of the dehumidistat. Two spade connector are provided
in the dehumidistat for wiring connections. See Fig. 3.
7. Mount the dehumidistat on the wall with the two
screws and wall anchors provided.
8. Snap on the cover on the mounting plate.
OPERATION
When the dehumidistat is installed, the humidity dial should
be set to the desired level. When the indoor humidity level at
the dehumidistat is exceeded, the ventilator will go into Override mode. Override mode will continue until relative humidity
drops below the set point of the dehumidistat.
It is not necessary to change the humidity setting every day.
To avoid window condensation, monitor the average weekly
temperature to find a comfortable level. Adjust the control
when needed.
DEHUMIDISTAT
Fig. 2 — Dehumidistat Wiring
EXTERNAL CONTACTS
ON VENTILATOR
DEHUM
WALL CONTROL
TIMER
+-
Fig. 3 — Dehumidistat Terminal Connections
Fig. 4 — Replacing Cover
2
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