Communicating Thermostats - Rheem RGPE series Installation Instructions Manual

COMMUNICATING THERMOSTATS

COMMUNICATING THER-
MOSTATS
The furnace is capable of communicat-
ing with a thermostat and condenser to
improve cooling and heat-pump airflow,
displaying active faults and active fur-
nace information at the thermostat and
improved diagnostics and troubleshoot-
ing.
WIRING A FURNACE FOR COM-
MUNICATIONS
MAXIMUM COMMUNICATING WIRE
LENGTHS (1, 2, R & C)
Max Wire Length – Thermostat to
Furnace = 1 1 0 0 0 0 F F T T @ 18 AWG*
Max Wire Length – Furnace to
Condenser = 1 1 2 2 5 5 F F T T @ 18 AWG*
Notes:
1. When using twisted pairs, be sure the
wires connected to pins labeled "1"
(recommended wire color = green)
and "2" (recommended wire color =
yellow) are a twisted pair.
2. Wires may be solid or stranded.
3. *Wire gage smaller than 18 AWG is
not approved or recommended for
this application.
4. When using existing wire from a pre-
vious installation, be sure to trim the
tip of the wire back past the insulation
and strip a small amount of insulation
from the wire to expose clean new
copper for the communicating con-
nections. Fresh copper must be
exposed when making the communi-
cating connections or communications
may not be properly established.
Figures 51 through 52 are wiring dia-
grams for connecting the furnace to an
approved ClimateTalk communicating
thermostat and approved Rheem or
Ruud communicating condenser.
The only approved configuration for
fully communicating systems is to install
dedicated wires directly from the fur-
nace to the thermostat and a separate
set of dedicated wires directly from the
furnace to the condenser. Note: The
only approved configuration for systems
with a communicating condenser
requires that four dedicated wires (1, 2,
R and C) be installed from the furnace
to the condenser.
TWO NOTES ABOUT COMMUNI-
CATING THERMOSTATS
1. When power to the thermostat has
been reset and/or the batteries are
replaced, the thermostat will respond
quickly to changes in room tempera-
ture as indicated by the room tem-
perature displayed at the thermostat.
84
However, after a two-hour period,
this will change and the thermostat
will take as long as five minutes for
every degree F to change the dis-
play. Therefore, for example a rapid
change of five degrees in room tem-
perature will not be correctly indicat-
ed at the thermostat for (up to) 25
minutes. This is done to buffer the
thermostat against rapid and insignif-
icant swings in temperature caused
by briefly opening a door or window.
This operation prevents excessive
cycling of the thermostat and is a
feature used in all modern ther-
mostats.
FIGURE 51
WIRING DIAGRAM – COMMUNICATING CONFIGURATION
2. For dual-fuel systems, once the
thermostat has switched over to
auxiliary heat (e.g. gas heat), sub-
sequent heat calls may also
immediately begin with auxiliary
heat regardless of the dual-fuel
changeover point and the actual
outdoor temperature or the differ-
ence between room temperatures
and setpoint. This is true as long
as the subsequent heat call is
within 12 minutes or less of end
of the previous heat call. The
actual time between heat calls
that will cause this operation
varies but should not exceed 12
minutes.
A-1114-01