22
Specifications subject to change without notice.
516 01 3604 04
Defrost
The defrost control mode is a time/temperature sequence.
There are two time components: The continuous run period
and the test/defrost cycle period. The temperature compo
-
nent is provided by Defrost Thermostat 1 and 2 (DFT1 and
DFT2) mounted on the outdoor coil.
The continuous run period is a fixed time period between
the end of the last defrost cycle (or start of the current Heat
-
ing cycle) during which no defrost will be permitted. This pe
-
riod can be set at 30, 60, 90 or 120 minutes by changing the
positions of DIP switches SW1 and SW2 (see Fig. 37 and
Table 7). The default run period is 60 minutes for size 120
units.
Shorting the jumpers for a period of 5 to 20 seconds by
-
passes the remaining continuous run period and places the
unit in a Forced Defrost mode. If the controlling DFT is
closed when this mode is initiated, the unit will complete a
normal defrost period that will terminate when the con
-
trolling DFT opens or the 10 minute defrost cycle limit is
reached. If the controlling DFT is open when this mode is
initiated, the Defrost cycle will run for 30 seconds. Both
modes end at the end of the Defrost cycle.
Fig. 37 — DIP Switch Settings - Defrost Board
UNIT WITHOUT THRU-BASE CONNECTION KIT
Pass the thermostat control wires through the bushing on
the unit end panel. Route the wire through the snap-in wire
tie and up to the web bushing near the control box. Route
the wire through the bushing and into the bottom left side of
the control box after removing one of the two knockouts in
the corner of the box. Using a connector at the control box
to protect the wire as it passes into the control box. Pull the
wires over to the terminal strip at the upper left corner of the
Central Terminal Board (CTB). Use the connector at the
control box and the wire tie to ensure that the thermostat
wire is tight and will not be damaged by contact with the
condenser coil. See Fig. 38.
NOTE: If thru-the-bottom connections accessory is used,
refer to the accessory installation instructions for information
on routing power and control wiring.
Fig. 38 — Thermostat Wire Routing
HEAT ANTICIPATOR SETTINGS
Set heat anticipator settings at 0.14 amp for the first stage
and 0.14 amp for second-stage heating, when available.
ELECTRIC HEATERS
RHH units may be equipped with field-installed accessory
electric heaters. The heaters are modular in design, with
heater frames holding open coil resistance wires strung
through ceramic insulators, line-break limit switches and a
control contactor. One or two heater modules may be used
in a unit.
Heater modules are installed in the compartment below the
indoor (supply) fan outlet. Access is through the indoor ac
-
cess panel. Heater modules slide into the compartment on
tracks along the bottom of the heater opening. See Fig. 39.
CAUTION
UNIT DAMAGE HAZARD
Failure to follow this caution may result in equipment
damage.
Not all available heater modules and single point boxes
may be used in every unit. Use only those heater mod
-
ules that are UL listed for use in a specific size unit. Re
-
fer to the label on the unit cabinet for the list of approved
heaters and single point boxes.
