Rheem 96MDV Series Installation Instructions Manual Download

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INTEGRATED FURNACE CONTROL

HUMIDIFICATION/DEHUMIDIFICATION

An optional 24VAC humidistat can be installed as

shown in Figures 46 thru 49. With the optional humidi-
stat, two separate conditions must be met before hu-
midification can begin 1). There must be a call for heat
and the blower must be engaged and 2.) The humidis-
tat must determine that there is a need for humidifica-
tion.  Note: Dipswitch S2-8 (labeled “ODD”) enables
(“ON”) or disables (“OFF”) de-humidification opera-
tion.  However, it has no affect on humidification oper-
ation.  If this switch is set to the “ON” position and no
humidistat is installed, the cooling airflow will be per-
manently reduced by approximately 15% giving less
than optimal performance and possibly causing prob-
lems. It is not recommended to leave this switch in the
“ON” position without a humidistat installed.

Control of dehumidification in cooling and/or humidifi-

cation in heating can be done with a variety of meth-
ods depending on whether there is a communicating
thermostat or a humidistat available and depending on
the type of operation desired.

With systems configured with communicating thermo-

stats and condensers, dehumidification is controlled
by the thermostat and is not affected by the position of
dipswitch SW2-1 or the voltage at the thermostat input
T2 labeled “HUM STAT” on the furnace. To determine
which wiring diagram and method to use, select from
the following configurations:

A. HUMIDIFICATION CONTROL ONLY WITH NO

DEHUMIDIFICATION (REQUIRES OPTIONAL
HUMIDIFIER).

A1. WITH COMMUNICATING THERMOSTAT

Humidifier control is included with EcoNet
communicating thermostats.  To wire the fur-
nace for humidification control using an
EcoNet communicating thermostat, refer to
the wiring diagram in Figure 46.  Be sure not
to install the jumper between “R” and “HUM
STAT” on the furnace control.  Installing this
jumper will operate the humidifier any time
there is a heat call.  Without the jumper, the
humidification call from the thermostat must
be active and a heat call must be present with
the blower running.

A2. WITH NON-COMMUNICATING THERMO-

STAT

A2-1 CONTINUOUS HUMIDIFIER OPERA-
TION DURING HEATING.

For continuous humidifier operation during
heating, refer to Figure 46 and make sure to
install the jumper between the thermostat ter-
minals labeled “R” and “HUM STAT”. A sepa-
rate humidistat is not required for this
configuration and the humidifier will turn on
whenever there is a call for heat and the
blower is running.

A2-2 CONTROLLED HUMIDIFIER OPERA-
TION USING A HUMIDISTAT (REQUIRES
OPTIONAL HUMIDISTAT).

Controlled humidification can be accom-
plished using a humidistat as shown in Fig-
ures 47 or 48.  These figures show installation
of a humidifier with external and internal
power supplies respectively.  Dehumidification
operation will be disabled if the dipswitch S2-8
is in the “OFF” position.  If this switch is in the
“ON” position, dehumidification control will be
active.

B. DEHUMIDIFICATION CONTROL WITH NO HU-

MIDIFICATION

B1. WITH COMMUNICATING THERMOSTAT

For communicating thermostats listed with this
furnace, dehumidification is controlled auto-
matically when selected at the thermostat and
additional wiring is not necessary. The actual
airflow demand (reduced for dehumidification)
is requested of the furnace by the thermostat.

B2. WITH NON-COMMUNICATING THERMO-

STAT (REQUIRES OPTIONAL HUMIDISTAT)

Control of dehumidification only (no humidifi-
cation) can be accomplished by installing an
optional humidistat as shown in Figure 49.
The dipswitch S2-8 must be set to the “ON”
position. If this switch is not turned “ON”, de-
humidification operation will not take place.
Further, if this switch is “ON” and no humidis-
tat is installed, airflow in cooling will be perma-
nently reduced by approximately 15%.

C. HUMIDIFICATION AND DE-HUMIDIFICATION

CONTROL (REQUIRES OPTIONAL HUMIDI-
FIER).

C1. WITH COMMUNICATING THERMOSTAT

Humidifier control is included with EcoNet
communicating thermostats. To wire the fur-
nace for humidification and dehumidification
control using an EcoNet communicating ther-
mostat, refer to the wiring diagram in Figure
46. Be sure not to install the jumper between
“R” and “HUM STAT” on the furnace control.
Installing this jumper will operate the humidi-
fier any time there is a heat call and dehumidi-
fication will never take place when in cooling.
Without the jumper, a humidification call from
the thermostat must be active and a heat call
must be present with the blower running for
the “HUM” relay contacts to close.