Accessories; Furnace Twinning - Rheem Gra Series Installation Instructions Manual

fireplace, sun rays, lamps, televisions,
radios or air streams from registers.
Refer to instructions packed with the
thermostat for "heater" selection or
adjustment.

ACCESSORIES

FIELD-INSTALLED
OPTION ACCESSORIES
ELECTRONIC AIR CLEANER
Line voltage power can be supplied
from the screw terminal "EAC" and a
line voltage neutral screw terminal on
the control board. NOTE: Spade
terminals only are provided on (-)GRJ
and (-)GTJ models. This will power
the electronic air cleaner whenever
the circulating air blower is in
operation.
HUMIDIFIER
Line voltage power can be supplied
from screw terminal "HUM" to a line
voltage neutral screw terminal on the
control board. This will power the
humidifier whenever the burner is
on and the circulating air blower is
operating in the heating mode.
NOTE: Maximum current – 1.0 amps
for each option.
NOTE: Humidifier output is not
available on (-)GRJ and (-)GTJ
models.
ALTERNATE (LEFT SIDE)
DRAIN KIT - RXGY-H01
(DOWNFLOW MODELS
ONLY)
42

FURNACE TWINNING

INSTALLATIONS
Twinning operation of two furnaces,
installed side-by-side, connected by a
common duct system with main
power supplied by the same source,
and controlled by a common
thermostat can be done with the
UT Electronic Controls 1028-928
integrated control boards.
IMPORTANT: Twinning of (-)GRJ-
and (-)GTJ- units requires an
accessory twinning kit. Refer to the
specification sheet for proper kit. Do
not attempt to twin these models by
using the instructions below.
IMPORTANT: Only twin furnaces
with identical control boards.
IMPORTANT: Only bottom returns
can be used. No more than two
furnaces can share the same supply
and return. Furnaces must have
same heating and blower capacity.
Twinning furnaces must operate off
the same phase of power.
It should be noted that both blowers
will run simultaneously when there is
a call for heating, cooling or fan.
The "OK" LED will flash if twinning is
not set up properly.
UT ELECTRONIC CONTROLS
1028-928 CONTROL BOARD
1. Single Stage Operation
(See Figure 46)
a. Control board "ONE" is on
furnace connected to the
thermostat.
b. The 24 VAC supply to both
control boards must be in
phase with each other.
c. Connect the "C," "W" and
"TWIN" terminals to
counterparts on each control.
d. Both control boards must have
switch #3 in the "ON" position.
2. Two Stage Operation
(See Figure 47)
a. Follow above instructions.
Connect "W2" on thermostat
to "W" on control board
"TWO."