Saswell T21STK-2 User manual

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OPERATING
T21STK-2
INSTRUCTION

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T21STK-2 SINGLE STAGE PROGRAMMABLE THERMOSTAT
1 Heat / 1 Cool single stage thermostat.
5+2 Programmable, Compatible with heat pump system
Installation and Operation Manual
Specification:--------------------------------------------------------------------------------
Power Supply: 20VAC-30VAC 50-60HZ or Battery powered.
Terminal Load: 1.0A per terminal, 3.0A maximum total load
Set Point Temperature Range: 45ºF to 90ºF (7ºC to 32ºC).
Accuracy: +/- 1ºF or +/- 0.5ºC.
Dimensions: 6.0” W X 4.7” H X 1.1” D
Color: White

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FEATURES:---------------------------------------------------------------------------------
Large LCD display with backlight, continuous backlight option
Simultaneous heat and cool set point storage
Display of room temperature, set temperature and current time simultaneously
Fan switch with ON and AUTO
Permanent user setting retention during power loss. No batteries are required.
Operates from 24VAC, or from 2 size “AA” alkaline batteries
Optional temperature display of Fahrenheit or Celsius scale.
Air Filter change Indicator
Low Battery Indicator
Display temperature calibration.
Separate 5-day (weekday) and 2-day (Saturday/Sunday) programming with

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four separate time/temperature periods per day.
Intelligent Recovery Option for optimizing comfort
IMPORTANT SAFETY INFORMATION-------------------------------------------
Always turn off power at the main power source by removing the fuse, or
switching the circuit breaker to the off position before installing, removing,
cleaning, or servicing this thermostat.
Read all of the information in this manual before installing this thermostat.
Use a professional contractor to install this thermostat.
This is a 24VAC low-voltage thermostat. DO NOT INSTALL ON VOLTAGES
HIGHER THAN 30 VAC.
ALL wiring must conform to local and national building and electrical codes
and ordinances.

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Do not short (jumper) across terminals on the gas valve or at the system
control to test installation. This will damage the thermostat and void the
warranty.
Do not switch the system to cool if the temperature is below 50ºF (10ºC). This
can damage the air conditioning system and may cause personal injury.
Replace batteries when the battery icon indicates the low battery message.
Change the Air Filter when the Filter Change Icon begins blinking.
Use this thermostat only as described in this manual.
REMOVE THE OLD THERMOSTAT--------------------------------------------------------------------------
WARNING!: Electrical Shock Hazard
1. Turn off power at the main service panel by removing the fuse or switching the
appropriate circuit breaker to the OFF position before removing the existing
thermostat.

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2. Turn off power to the heating and cooling system by removing the fuse or
switching the appropriate circuit breaker off.
3. Remove the cover of the old thermostat. This should expose the wires.
4. Label the existing wires from the existing thermostat before removing.
5. After labeling the wires, remove the wires from the wire terminals.
6. Remove the existing thermostat from the wall.
7. Refer to the following section for instructions on how to install this thermostat.

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INSTALL THE THERMOSTAT---------------------------------------------------------------------------------
ATTACH THERMOSTAT BASE TO WALL PULL THE COVER OFF THE BASE.

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WARNING!: Electrical Shock Hazard
Turn off power at the main service panel by removing the fuse or switching the
appropriate circuit breaker to the OFF position before removing the existing thermostat.
1. Turn off power to the heating and cooling system by removing the fuse or
switching the appropriate circuit breaker off.
2. Place the system switch (COOL/OFF/HEAT) in the OFF position.
3. Place the FAN (AUTO/ON) switch in the AUTO position.
4. Gently pull the cover straight off the base. (See figure 1.)
5. Put the thermostat base against the wall where you plan to mount it. (Be sure
the wires will feed through the wire opening in the base of the thermostat.)
6. Mark the placement of the mounting holes.
7. Move the base out of the way. Drill mounting holes. Use a hammer to tap in
the supplied anchors into the mounting holes.

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8. Fasten the base loosely to the wall as shown in Figure 1, using two mounting
screws. Place a level against the bottom of the base and adjust until level,
then tighten the screws. (Leveling is for appearance only, and will not affect
thermostat operation.)
9. Insert stripped, labeled wires into matching wire terminals. See “Wiring
Diagrams”, Figure 2.
CAUTION: Be sure exposed portions of wires do not touch other wires.
10. Tighten screws on terminal block. Gently tug on each wire to be sure of
proper connection. Double check that each wire is connected to the proper
terminal.
CAUTION: Installing batteries backwards can damage the thermostat.

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11. Install two fresh “AA” alkaline batteries in the battery compartment. Be sure
to match positive (+) ends of batteries with positive (+) battery terminals in the
battery compartment. (The thermostat will operate from 2 size “AA” alkaline
batteries or 24VAC power. When operated from 24VAC power, your thermostat will
maintain time and continuously display the temperature during a loss of AC power
with the batteries installed.)
12. Replace the cover on the thermostat by snapping it in place.
13. Turn on power to the system at the main service panel.
14. Test thermostat operation as described in the following section.
FAN OPTION SWITCH
Read the following information before setting the fan option switch (See figure 3). If you
are unsure of your application, contact a qualified service person.

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This thermostat is configured from the factory to energize the fan on a call for heat. If
your system is an electric heat or heat pump that REQUIRES the thermostat to turn on
the fan on a call for heat, place the fan option switch in the ELEC position. If your system
does not require the thermostat to energize the fan on a call for heat such as fossil fuel
(gas, oil, etc.), forced air system as well as hydraulic heating systems, place the fan
option switch in the GAS position.
BATTERY OPERATION
The thermostat will operate from 2 size “AA” alkaline batteries or 24VAC power. When
operated from batteries, connection to the “C” (common) or (neutral) terminal is not
required.
NOTE: When operated from batteries (No “C” terminal connection), the LCD display
backlight options are limited to option 1 (disabled) or option 2 (30 second illumination
after each button press).

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Wiring Diagrams
Figure 3, Typical wiring diagram for heat/cool,
5 wire two transformer system.

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Figure 4, Typical wiring diagram for heat/cool,
4 wire, single transformer system

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Note* Jumper required in heat pump mode.
Figure 5, Typical wiring diagram for heat pump
with reversing valve

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CHECK THERMOSTAT OPERATION------------------------------------------------------------------
If at any time during testing your system does not operate properly, contact a qualified
service person.
Turn on power to the system.
Fan Operation
Move the system switch to the OFF position. If your system does not have a “G” (Fan)
terminal connection, skip to the Heating System.
1. Move the fan switch to the ON position. The blower should begin to operate.
2. Move the fan switch to the AUTO position. The blower should stop
immediately.
Heating System
1. Move the SYSTEM switch to the HEAT position. If the auxiliary heating
system has a standing pilot, be sure to light it.

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2. When the (FA)st heating cycle rate is selected in the configuration
menu, (see configuration menu item 2), the thermostat will call for heat at
0.5ºF (0.5ºC) below set-point, and turn off at set point. When the (SL)ow
heating cycle rate is selected, the thermostat will call for heat at 1.5ºF (1.5ºC)
below set-point, and turn off at set-point. When the thermostat calls for heat,
the display will show Heat On. If the Heat On display is flashing, the
compressor lockout feature is operating in the heat pump mode. (Note: See
Configuration menu item 8).
Cooling System
CAUTION!: To prevent compressor and/or property damage, if the outdoor
temperature is below 50ºF (10ºC), DO NOT operate the cooling system.
1. Move the SYSTEM switch to the COOL position.

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2. When the (FA)st cooling cycle rate is selected in the configuration
menu, (see configuration menu item 2), the thermostat will call for cooling at
0.5ºF (0.5ºC) above set-point, and turn off set point. When the (SL)ow cool
cycle rate is selected, the thermostat will call for cooling at 1.5ºF (1.5ºC) above
set-point, and turn off at set-point. When the thermostat calls for cooling, the
display will show COOL On. If the COOL On display is flashing, the
compressor lockout feature is operating. mode. (Note: See Configuration
menu item 8).
If all functions operate properly, the thermostat is installed correctly.
Replacing Batteries
If your thermostat was pre-installed, the batteries may be in place. If the
battery icon on the display is flashing, it indicates that the batteries need to
be replaced. When the thermostat is powered only by battery, the battery icon
will flash for approximately 2 months before the batteries are expected to

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expire. Then the thermostat will cut power to the heating/cooling system.
Important: Replace the batteries when the low battery message flashes on
the display. This will keep the thermostat operating properly. With two “AA”
batteries installed, your thermostat will maintain time and continuously display
the temperature during a loss of AC power.
1. Place the COOL/OFF/HEAT switch in the OFF position.
2. Put the FAN AUTO/ON switch in the AUTO position.
3. Gently pull the cover straight off the base.
4. Install two “AA” alkaline batteries in the battery
compartment. Be sure to match the positive (+) ends of the
batteries with the positive terminals marked in the battery
compartment.

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1. Configuration Menu
The configuration menu allows you to set certain thermostat operating
characteristics to your system or personal requirements. Move the SYSTEM
switch to the OFF position, then press and hold the PRGM and RUN buttons for
3 seconds to enter the configuration menu. The display will show the first item in
the configuration menu. Press the PRGM button to move to the next menu item,
or press TIME to return to a previous menu item. To revert to factory default
settings, press the RESET button (See Fig. 3). All user’s changed settings will
revert to factory default settings, including program settings. Use the ▲or▼
buttons to select. To exit the configuration menu and return to normal operation,
press the RUN button. If no buttons are pressed within 130 seconds, the
thermostat will exit the configuration menu.
The configuration menu chart summaries the configuration options. An
explanation of each option follows.

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