Carrier P274-0150 User Manual

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OWNER’S
MANUAL

Part Number P274-0150

IMPORTANT: Read entire instructions before pro­gramming the thermostat.

GENERAL

Totaline® thermostats are wall-mounted, low-voltage ther­mostats which maintain room temperature by controlling the
operation of an HVAC (heating, ventilation and air condition­ing) system using separate heating and cooling set points and
auto-changeover capability.

Batteries are not required. During power interruption the
internal memory stores set points indefinitely.

OPERATION

Thermostat Display —

ed in the top center of the thermostat. See Fig. 1. The following
information can be displayed on the screen:

• mode (OFF, COOL, AUTO, or HEAT)

• fan setting (ON or AUTO)

• room temperature

• desired temperature

• clean filter status

• outdoor temperature (optional)

Thermostat Buttons and Operation — The Up and

Down Arrows are used to change the current, desired tempera­ture set point. The Up and Down Arrows are accessible from
the outside of the thermostat. Press the up or down arrow. The
LCD readout will be illuminated and the heating or cooling
temperature set point will be displayed, but will not change.
HEAT, or COOL next to the temperature display indicates
which temperature set point is being displayed. Continue to
press up or down arrows until desired heating or cooling tem­perature set point is displayed. Press the Mode button to select
the second temperature setting (either HEAT or COOL).

NOTE: Your COOL setting must be at least 2 degrees higher
than the HEAT setting. The thermostat will automatically
change the previously set temperature to maintain that
2-degree difference.

FAN BUTTON OPERATION — The Fan button selects fan
operation. When the fan is set to ON, the fan will run continu­ously for improved air circulation. The FAN icon will be dis­played on the LCD. When the fan is set to AUTO, the fan will
run during heating and cooling operation only and provides
energy savings.

The thermostat display is locat-

Residential

Thermostat

MODE BUTTON OPERATION — The Mode button selects
the operating mode of the thermostat. If OFF is selected, the
thermostat will not enter Heating or Cooling mode. If HEAT is
selected, the thermostat will only enter Heating mode (if the
room temperature is below the heating set point). If COOL is
selected, the thermostat will only enter Cooling mode (if the
room temperature is above the cooling set point). If AUTO is
selected, the thermostat will enter Heating or Cooling mode
based on the room temperature and the heating and cooling set
points.

Auto-Changeover — When the thermostat mode is set

to AUTO, the thermostat will provide automatic changeover
from Heating to Cooling mode and Cooling to Heating mode
when required. The thermostat will automatically switch to
maintain the desired temperature setting. The thermostat does
not need to be manually changed from heating to cooling or
cooling to heating operation.

When the auto-changeover mode is selected, a change from
heat to cool (or vice versa) will not occur until an opposite
mode demand has existed for 20 minutes. If the set point is
changed, the 20-minute requirement is ignored.

NOTE: It is recommended that auto-changeover mode not be
used if the outdoor temperature is consistently lower than 50 F
or greater than 80 F. In these cases, select Heating or Cooling
mode only.

Reset Filter — The CLEAN FILTER icon reminds the

user when it is time to change or clean the filter of the unit. The
Reset Filter function is initiated by Pressing the RESET
FIL TER button after you have changed or cleaned your filter to
restart the timer. The Reset Filter function is used to clear the
CLEAN FILTER icon on the display screen.

Display Outdoor-Air Temperature — When the Up

and Down Arrows are pressed at the same time, the display
will show the temperature of the sensor wired to the thermo­stat. The display then returns to normal. If a sensor is not con­nected, then “--” is displayed.

The valid temperature range for the outdoor-air sensor is
–38 to 145 F .

POWER OUT AGE — An internal power source maintains the
desired temperature settings indefinitely .

System Error — The temperature sensor failure indicator

sends a -- reading to the LCD display. This indicates your ther­mostat’s internal or outdoor temperature sensor is no longer
able to measure temperatures. An E2 reading on the LCD dis­play means there is not enough voltage for the system to
operate.

Manufacturer reserves the right to

discontinue, or change at any time,

specifications or designs without notice

and without incurring obligations.

REPLACEMENT COMPONENTS DIVISION LITERATURE NUMBER P274-6SO
© CARRIER CORPORATION 1106 6-01 REPLACES: NEW
PRINTED IN U.S.A. CATALOG NUMBER 570-458

*OUTDOOR TEMPERATURE
DISPLAY SHOWS THE

OUTDOOR TEMPERATURE

FAN BUTTON CHOOSES
BETWEEN ON OR AUTO
FAN OPERATION.

MODE
OFF
COOL
HEAT
AUTO

FAN
AUTO
ON

CLEAN FILTER

CLEAN FILTER INDICATOR LETS YOU

KNOW IT IS TIME TO CLEAN OR REPLACE
YOUR SYSTEM’S AIR FILTER

RESET FILTER BUTTON

RESTARTS THE TIMER THAT
DETERMINES THE NEXT AIR
FILTER CHANGE OR
CLEANING

MODE BUTTON SELECTS
BETWEEN OFF, HEAT,
COOL, AND AUTO
OPERATION.

Thermostat

RESET FILTER

FAN MODE

NOTE: Not all messages displayed in the above illustration will appear at once in any situation.

Fig. 1 — Thermostat Display and Buttons

ROOM TEMPERATURE
DISPLAY SHOWS THE CURRENT

ROOM TEMPERATURE ON THE

LCD READOUT.

UP AND DOWN ARROWS

INCREASE OR DECREASE THE
DESIRED TEMPERATURE
SETTING.

*AVAILABLE AS AN ACCESSORY.

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