Venstar T1050 Programmable Thermostat
PREPARATION
- Proper installation of the thermostat will be accomplished by following these step by step instructions. If you are unsure about any of these steps, call a qualified technician for assistance.
- Make sure your Heater/Air Conditioner is working properly before beginning the installation of the thermostat.
- Carefully unpack the thermostat. Save the screws, wall anchors, and instructions.
- Turn off the power to the Heating/Air Conditioning system at the main fuse panel. Most residential systems have a separate breaker for disconnecting power to the furnace.
REMOVE & REPLACE OLD THERMOSTAT
- Remove the cover of the old thermostat. If it does not come off easily check for screws.
- Loosen the screws holding the thermostat base or subbase to the wall, and lift away.
- Disconnect the wires from the old thermostat. Tape the ends of the wires as you disconnect them, and mark them with the letter of the terminal for easy reconnection to the new thermostat.
- Keep the old thermostat for reference purposes, until your new thermostat is functioning properly.
WIRE CONNECTIONS
If the terminal designations on your old thermostat do not match those on the new thermostat, refer to the chart below, or the wiring diagrams that follow.
C may not be used on all systems.
O/b is used if your system is a Heat Pump.
Sample Wiring Diagram
Gas or Electric Heat
5 Wire, 1 Stage Cooling, 1 Stage Gas Heat 
* If using first stage electric heat, this option must be selected ON (see page 12, step 5 of Owner’s Manual).
4 Wire, 1 Stage Cooling, 1 Stage Gas Heat 
* If using first stage electric heat, this option must be selected ON (see page 12, step 5 of Owner’s Manual).
6 Wire, 2 Stage Cooling, 1 Stage Gas Heat 
* If using first stage electric heat, this option must be selected ON (see page 12, step 5 of Owner’s Manual).
* If using first stage electric heat, this option must be selected ON (see page 12, step 5 of Owner’s Manual).
7 Wire, 2 Stage Cooling, 2 Stage Heat 
If using first stage electric heat, this option must be selected ON (see page 12, step 5 of Owner’s Manual).
Commercial heat pumps do not have the heat pump turned ON in advanced setup (see page 11, step 3 of Owner’s Manual).
Heat Pump
5 Wire, 1 Stage Cooling, 1 Stage Heat-Heat Pump* with O or b reversing valve**.
Residential Heat Pumps, split systems & package units, with no auxiliary heat. 
* This option must be selected ON during advanced setup (see page 11, step 3 of Owner’s Manual).
** This option must be selected O or b during advanced setup (see page 12, step 4 of Owner’s Manual).
6 Wire, 1 Stage Cooling, 2 Stage Heat-Heat Pump* with O or b reversing valve**.
Residential Heat Pumps, split systems & package units, with auxiliary heat.
* This option must be selected ON during advanced setup (see page 11, step 3 of Owner’s Manual).
** This option must be selected O or b during advanced setup (see page 12, step 4 of Owner’s Manual).
TEST OPERATION
- Turn the power on to the Heating/Air Conditioning system.
- Press the MODE button repeatedly until the HEAT icon appears on the display. Press the UP or DOWN buttons until the set temperature is 10 degrees above room temperature. The HVAC unit should energize in the heating mode.
- Press the MODE button repeatedly until the COOL icon appears on the display. Press the UP or DOWN buttons until the set temperature is 10 degrees below room temperature. The HVAC unit should energize in the cooling mode.
NOTE: Most equipment has a time delay of 5 minutes between cool cycles. This feature is defeatable on the thermostat (see page 13, step 8 of Owner’s Manual). - Press the UP button until the setpoint is equal to the room temperature. Press the FAN button to Fan On. The fan should turn on and run continuously.
TROUBLESHOOTING
- SYMPTOM: When using 4 wires (R, G, W, Y), the air conditioning equipment tries repeatedly to turn on, but cannot. At times the display dims or disappears.
- CAUSE: There is not enough power available to “power share”.
- REMEDY: Connect a 250 ohm, 10-watt power
- SYMPTOM: The air conditioning does not attempt to turn on.
- CAUSE: The compressor timer lockout may prevent the air conditioner from turning on, for a period of time.
- REMEDY: See page 13 of the Owner’s Manual and configure step 8 to defeat the 5- minute compressor lockout.
- SYMPTOM: The display is blank.
- CAUSE: Lack of proper power.
- REMEDY: Make sure power is turned on to the furnace and 24vac between R & W. If C is used, 24vac between R & C. Vensta
- SYMPTOM: When controlling a residential heat pump, and asking for cooling, the heat comes on.
- CAUSE: The heat pump is not selected “ON” in the Advanced Setup.
- REMEDY: See page 11 of the Owner’s Manual
- SYMPTOM: When calling for cooling, both the heat and cool come on.
- CAUSE: The thermostat is configured to control a heat pump and the HVAC system is a “conventional” (non-heat pump) system.
- REMEDY: See page 11 of the Owner’s Manual and set step 3 to OFF to enable gas-electric operation.
REFERENCE:
Download Manual:
Venstar T1050 Programmable Thermostat Installation Instructuion
OTHER MANUALS
Venstar T1050 Programmable Thermostat Thermostat Owner Manual
Venstar T1050 Programmable Thermostat Installation Instructuion