Option 12--Defrost Heat Select
This option allows installer to select the amount of heat provided
by Thermidistat Control during a heat pump defrost cycle. This
can be very helpful in maintaining a comfortable leaving air
temperature during defrost. The Thermidistat Control senses
when defrost is in progress by monitoring voltage placed on the
O line by the heat pump while defrosting. It responds by turning
on selected combination of Wl and W2 during defrost. Note that
this is very different from the operation of an ordinary thermostat,
which cannot sense defrost in progress and only turns on its W
outputs in response to a temperature demand. Combinations of
Wl and W2 are selected as shown in Table 1.
Table 1 Wl/W2 Outputs
Selection
0
1
2
Definition
Wl nor W2 is turned on. This is factory default.
Only W1 is turned on.
Both W1 and W2 turned on.
Only W2 turned on (available only if 3-stage
heat is selected.
The selection procedure is given below. If 0 is selected, operation
is like that of an ordinary thermostat, and a wire is required
between W2 of outdoor unit and a selected W on indoor unit.
When selection 1, 2. or 3 is made, no wire should be connected
from outdoor W2 because this connection may override selection
made. Obviously the heater must be in 2 sections, and fan coil
jumper must be removed between Wl and W2 for there to be a
difference between selections 1, 2, and 3. For most heaters. Wl is
lower wattage heater, and W2 is higher, although some have
equal elements for Wl and W2. Consult fan coil/heater
combination for the actual wattage connected to each of Wl and
W2.
In Hybrid Heat applications, above selection choices apply and
can be used to select low or high heat if furnace is 2 stage. Wl
will produce low heat. Wl and W2 together produce high heat.
This option provides no value with single-stage furnaces because
only 1 value of heat is available.
The selection choices guarantee selected outputs will be on
during defrost. If room temperature demand requires additional
heat, it will be supplied, resulting in additional outputs being
turned on. If room overheats, specified outputs will not turn off,
guaranteeing a sufficiently warm leaving air temperature during
defrost. Temperature overshoot during defrost can occur, but is
almost never noticeable because of the short duration of the
defrost cycle (4 minutes typical, 10 minutes maxinmm).
An additional feature of Thermidistat Control defrost is that it
always allows defrost cycle to run to completion. The
Thermidistat Control leaves the Y output on as long as outdoor
unit holds voltage on the O line, even if it is satisfied. This
prevents premature termination of defrost cycles, which occur
with normal thermostats.
TO SELECT
1. Enter configuration mode if not already there. See Step 4
"To Enter Configuration Mode." Use up and down
buttons to make small (now flashing) display indicate 12.
2. Press SET TIME/TEMP button once to flash large display.
3. Use up or down buttons to move between 0, 1, 2, or 3 (if
available) on large display. See Table 1 for effect of these
choices. Factory default is 0.
4. Press SET TIME/TEMP button again to flash upper small
display for selection of another option, or press END to
exit configuration mode.
Option 13--Room Temperature Offset Adjust
This option allows calibration (or deliberate miscalibration) of
room temperature sensor. There are various reasons why
homeowners may want to have displayed temperature adjusted to
a higher or lower value. The selected number is number of
degrees Fahrenheit. plus or minus, which will be added to actual
temperature. The numbers can range between -5 and +5. Factory
default is 0. This adjusted value will be used as actual temperature
for both display and control action. For example, if 2 is selected,
72°F actual will read 74_'F. If set point is 72°F. the room will
control to an actual temperature of 70°F which will be displayed
and acted upon as if it were 72"F. The effect is that a positive
number selection will make the room temperature lower and vice
versa. The Thermidistat Control is calibrated within an accuracy
of plus or minus I°F when shipped from the factory, so this
adjustment will provide the best accuracy when set to 0.
TO SELECT
1. Enter configuration mode if not already there. See Step 4
"To Enter Configuration Mode." Use up and down
buttons to make small (now flashing) display indicate 13.
2. Press SET TIME/TEMP button once to flash large display.
3. Use up or clown buttons to move between -5, -4, -3, -2.
-1.0, 1, 2, 3, 4, or 5 on large display. Factory default is 0.
4. Press SET TIME/TEMP button again to flash upper small
display for selection of another option, or press END to
exit configuration mode.
Option 14--Heat/Cool Dead Band Adjustment
This option selects the minimum difference between heat and
cool set points. A larger difference saves energy and a smaller
difference decreases temperature difference between heating and
cooling. Factory default is 2, which means cooling set point must
be a minimum of 2 ° above heating set point. An attempt to move
them closer will result in one "pushing" the other to maintain the
required difference.
Depending on set points, moving dead band closer than 2 ° may
result in regular cycling between heat and cool when AUTO
mode is selected. However, this cycling cannot occur more often
than 1 transition every 20 minutes. The system has a built-in
requirement that it cannot switch between heat and cool without a
20 minute "off' time between the 2 operations. Specifically, to
switch from 1 mode to the other, there must be no demand for the
old mode and a demand for the new mode, and this must exist
continually for 20 minutes before transition to the new mode will
Occur.
TO SELECT
1. Enter configuration mode if not already there. See Step 4
"To enter Configuration Mode." Use up and down buttons
to make small (nov," flashing) display indicate 14.
2. Press SET TIME/TEMP button once to flash large display.
3. Use up or down buttons to move between 0, 1, 2, 3, 4, 5,
or 6 on large display. Factory default is 2.
4. Press SET TIME/TEMP button again to flash upper small
display for selection of another option, or press END to
exit configuration mode.
Option 15--Enable Auto Mode
This option allows the installer to enable or disable AUTO mode
(automatic changeover between heat and cool). When disabled,
AUTO icon does not appear when successive presses of MODE
button are used to move between OFF. HEAT, COOL, and
EHEAT (in heat pump systems). Factory default is ON (AUTO
enabled).
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