HONEYWELL T8112C Electronic Programmable Thermostats Installational Instruction

HONEYWELL T8112C Electronic Programmable Thermostats

GENERAL

The T8112 Programmable Thermostat provides energy savings for single-stage heating and cooling applications while providing reliable, precise temperature control.

FEATURES

• HEAT-OFF-COOL system switch.
• AUTO-ON fan switch.
• Separate programs for weekdays and weekends (5 day/2 day).
• Digital LCD display.
• Easy to program and install.
• Precise temperature control.
• Four daily energy saving programs.
• Compatible with most 24 Vac standing pilot, gas electronic ignition, oil or central electric systems.
• Requires two AA alkaline batteries.
• LCD flashes bAt Lo indicating low battery power.
• Isolated heating/cooling circuits.

SPECIFICATIONS

IMPORTANT The specifications given in this publication do not include normal manufacturing tolerances; therefore, an individual unit might not exactly match the listed specifications. Also, this product is tested and calibrated under closely controlled conditions, and some minor differences in performance can be expected if those conditions are changed.

• Model:
  T8112 Thermostat: Provides electronic programmable control for 24 to 30 Vac heating and cooling systems.
• Programming Keys:
  Eight program keys; without keyboard door.
• Electrical Rating:
  Battery operated (2 AA alkaline batteries).
• System and Fan Ratings:
  1.2A run; 7.5A inrush.
  Total cooling and fan load not to exceed 1.2A.
  
• Dimensions:
  See Fig. 1.
• Mounting:
  Mounts on mounting plate directly on wall. Mounting screws and wall anchors provided.
• Setpoint Range:
  45°F to 88°F (7°C to 31°C).
• Operating Ambient Temperature Range:
  40°F to 110°F (4°C to 43°C).
• Shipping Temperature Range:
  -20°F to 120°F (-29°C to -49°C).
• Temperature Display:
  Fixed or field selectable.
• Operating Relative Humidity:
  5 to 90 percent RH; noncondensing.
• Time Indication:
  12 hour with AM, PM indication.

ORDERING INFORMATION

When purchasing replacement and modernization products from your TRADELINE® wholesaler or your distributor, refer to the TRADELINE® Catalog or price sheets for complete ordering information, or specify:

1. Model Number.
2. Accessories, as desired.

If you have additional questions, need further information, or would like to comment on our products or services, please write or phone:

1. Your local Honeywell Home and Building Control Sales Office (check white pages of phone directory).
2. Home and Building Control Customer Logistics Honeywell Inc., 1985 Douglas Drive North Minneapolis, Minnesota 55422-4386 (612) 951-1000.

In Canada—Honeywell Controls Limited, 155 Gordon Baker Road, North York, Ontario M2H 2C9. International Sales and Service offices in all principal cities of the world. Manufacturing in Australia, Canada, Finland, France, Germany, Japan, Mexico, Netherlands, Spain, Taiwan, United Kingdom, U.S.A.

Cycles Per Hour Adjustment:

• Heating: Field adjustable to 3, 6, or 9 cph ±10 percent.
• Cooling: Factory set at 3 cph ±10 percent (not field adjustable).

Calibration:
Thermostat and thermometer self-calibrating to ±1.25°F.

Accessories:

• 205013 Isolation Relay Kit.
• 205014 Transformer Plug-in Kit.
• 205015 International Organization for Standardization Relay and Transformer.

INSTALLATION

When Installing this Product…

1. Read these instructions carefully. Failure to follow the instructions can damage the product or cause a hazardous condition.
2. Check the ratings given in the instructions and on the product and in the compatibility chart (Table 1) to make sure the product is suitable for your application.
3. Installer must be a trained, experienced service technician.
4. After installation is complete, check out product operation as provided in these instructions.

Compatibility
Check Table 1 to make sure the thermostat is compatible with the intended system.

Table 1. Compatibility Chart.

System Type	Compatible with T8112
Gas—Standing Pilot	Yes
Gas—Electronic Ignition	Yes
Gas-Fired Boilers	Yesa
Gas—Millivolt	No
Oil-Fired Boilers	Yesa
Oil-Fired Furnace	Yes
Electric Furnace	Yes
Electric Air Conditioning	Yes
Baseboard Electric (120/240 Line Volt)	No
Heat pumps/Multistage Equipment	No

a Compatible with 2-wire Honeywell zone valves.

All system types:
Not compatible with any 120/240 volt circuit.
Not designed for steam or gravity systems.
Not compatible with 2-wire White Rodgers no. 1361 Valves. Isolating relay required for 3-wire thermostats for zone valves.

WARNING
ELECTROCUTION HAZARD CAN CAUSE PROPERTY DAMAGE, SEVERE INJURY, OR DEATH.
Disconnect power supply before wiring to prevent electrical shock or equipment damage.

Location

Locate the thermostat about 5 ft (1.5m) above the floor in an area with good air circulation at average temperature.
Do not mount the thermostat where it can be affected by:— drafts or dead spots behind doors and in corners.

• hot or cold air ducts.
• concealed pipes and chimneys.
• unheated (uncooled) areas such as an outside wall behind the thermostat.

Mounting Plate Installation

(Fig. 2)

1. Hold mounting plate in position and mark the two holes for mounting.
2. Level for appearance only; thermostat functions properly even when not level.
3. Tighten the mounting screws.
4. Set aside the mounting plate.
5. Drill the two holes in the wall as marked.
   Drill 3/16 in. holes for drywall.
   Drill 7/32 in. holes for plaster or wood.
6. Reposition the mounting plate over the holes and pull wires through the wiring opening.
7. Loosely insert the two mounting screws into the holes.

Wiring Thermostat

All wiring must comply with local electrical codes and ordinances. Refer to Fig. 5 through 8 for typical hookups. A letter code is located near each terminal for identification.

CAUTION Disconnect power before wiring to prevent electrical shock or equipment damage.

1. Connect the system wires to the thermostat. See Fig. 3. A letter code is located near each terminal for identification.
   NOTE: Hold the thermostat as shown in Fig. 4 to minimize the need for wire extenders.
2. Securely tighten each terminal screw.
3. Push excess wire back into the hole.
4. Plug the hole with nonflammable insulation to prevent drafts from affecting thermostat operation.
5. Run the required number of wires to the thermostat location. Refer to Fig. 5 through 8 for typical wiring diagrams.
6. In 5-wire installations only, be sure to remove the factory installed jumper connecting the terminals R and Rc.

2-WIRE HEAT-ONLY (JUMPER INTACT)

Adjust Fan Operation Switch, as Required
The thermostat fan operation switch, labeled FUEL SWITCH (see Fig. 9) is factory set in the F position. This is the correct setting for most systems. If you have an electric heat system, set the switch to E. In systems with the G terminal connected, the E setting turns on the fan immediately with heating or cooling.

Adjust System On-Time as Required
The thermostat on-time is factory set for a warm air, gas or oil heating system. If you are installing it on another type of system, the system on-time must be adjusted by changing the setting of screws A and B on the back of the thermostat. Use the heating system table in Fig. 9 as a guide to minimize room temperature swings. The system on-time should be optimized according to the type of system. Setting the screw out one turn means turning the screw approximately 360°, or one complete turn.
NOTE: This thermostat does not have a setting for steam/ gravity air. Cycles would not be long enough for accurate temperature control.
NOTE: For condensing furnaces, follow manufacturer instructions.
IMPORTANT When using a high efficiency furnace such as a 90 percent or greater AFUE (Average Fuel Utilization Efficiency) unit, adjust screw A out one turn and screw B In one turn.
If you want a longer on-time, readjust screws A and B as follows (refer to Table 1 Compatibility Chart):

• Warm Air Furnace—set at the Hot Water setting (A—out one turn, B—in).
• Electric Furnace—leave at the Warm Air Furnace setting (A—in, B—in).
  NOTE: This thermostat does not have a setting for steam/ gravity air. Cycles would not be long enough for accurate temperature control.

Install Batteries

IMPORTANT Batteries must be installed for programming and operating the thermostat and heating/cooling system.

1. Use two AA alkaline batteries; nonalkaline batteries will not last as long.
2. Make sure the thermostat is set to the Off position.
3. Use a coin to remove the battery door (see Fig. 10).
4. Install the new batteries as shown, making sure positive and negative terminals are oriented correctly (see Fig. 11).
5. Replace the battery door.

When the batteries are running low, a bAt Lo indicator will flash for one to two months before batteries run out completely. Replace the batteries as soon as possible after the indicator starts flashing. If the batteries are not replaced when the bAt Lo indicator is flashing, the indicator eventually stops flashing. When the batteries are almost completely dead, bAt Lo will stay on without flashing, indicating that the thermostat and heating/cooling system have stopped working. The thermostat will not function after the batteries are completely dead, and the bAt Lo indicator disappears, leaving a completely blank display.
To remove the batteries, press down on the left ends. When the new batteries are installed within 20 to 30 seconds of removing the old ones, the thermostat does not have to be reprogrammed. If the display is blank, the batteries are dead or incorrectly installed and the thermostat has to be reprogrammed. See Owner’s Manual for reprogramming instructions.

IMPORTANT 
Although the thermostat has a low battery indicator, replace the batteries once a year to prevent the thermostat from losing time and programming due to lack of battery power.

Mounting Thermostat

1. Engage the tabs at the top of the thermostat and mounting plate. See Fig. 12.
2. Press the lower edge of the case to latch.
   NOTE: To remove the thermostat from the wall, first pull out the bottom of the thermostat and then remove the top portion.

PROGRAMMING THE THERMOSTAT

Set the Current Time/Day

To set the time:

1. Press and release the Clock/Day key once.
2. Press the Time keys ▲ or ▼ until the current time displays.

To set the day:

1. Press and release the Clock/Day key again.
2. Press the Time keys ▲ or ▼ until the current day displays.
3. Press the Run Program key.

Heating Program

To set the system switch to HEAT:

1. Press and release the Schedule key once. WAKE, Mon-Fri , and SET appear on the display.
2. Press the Time keys ▲ or ▼ to program WAKE time, and Temp keys ▲ or ▼ to program WAKE temperature for Mon-Fri.
3. Repeat this sequence for LEAVE, RETURN, and SLEEP.
4. Press the Schedule key until SAT, SUN, WAKE and SET appear on the display.
5. Press the Time keys ▲ or ▼ to program WAKE time, and Temp ▲ or ▼ to program WAKE temperature for Sat-Sun.
6. Repeat this sequence for SLEEP.

Cooling Program

1. Set the system switch to COOL and follow the same procedure as for the Heating Program.
2. After programming, adjust the fan and system switches as desired.
3. Press and release the Run Program key to start the program.

A Quick Guide for Operating or Making Changes
NOTE: The system switch must be set to Heat or Cool to perform the following.

To temporarily change the temperature for the current period only:

1. Press the Temp keys ▲ or ▼.
   The temporary indicator shows on the display and cancels itself at the next scheduled change.
2. To cancel sooner, press the Run Program key.

To hold a temperature indefinitely:

1. Press the Hold Temp key.
2. Press the Temp keys ▲ or ▼ .
3. To cancel, press the Run Program key.

To check the current temperature setting:
Press the Run Program key. (When using TEMPORARILY CHANGE or HOLD, pressing this key will cancel the change or hold.)

To check the programs:

1. Press the Schedule key repeatedly to see each time and temperature.
2. Press the Run Program key.

To cancel a program:

1. Press the Schedule key until the program to cancel appears
2. Press both the Time keys ▲ and ▼ together.

To permanently change a program:
Repeat the steps in the Heating Program or Cooling Program section as applicable.

To return to the normal program:
Press the Run Program key.

CHECKOUT AND SETTINGS

After the thermostat is mounted on the mounting plate, check operation as follows:

Heating
Do not check the heating system operation by jumpering the thermostat terminals at the primary control such as the gas valve, zone valve, or oil burner control. This will damage the thermostat. Instead, you could jumper R and Rc wires at the thermostat.
Move the system switch to HEAT and the fan switch to AUTO.
Press the TEMP key until the setting is about 10°F (6°C) above the room temperature. After a short delay, the heating should start and the fan should run (immediately if fan operation switch is set in E position).
Press the TEMP key until the setting is about 10°F (6°C) below the room temperature. The heating equipment should shut off.
Cooling	Cool   Off     Heat
To avoid possible compressor damage, do not operate the cooling system when the outside temperature is below 50°F (10°C). See the compressor manufacturer instructions for further information. NOTE: When the cooling setting is changed, the thermostat can delay up to five minutes before turning on the air conditioner to protect the compressor.
Move the system switch to COOL and the fan switch to AUTO.
Press the TEMP key until the setting is about 10°F (6°C) below room temperature. The cooling equipment and fan should start.
Press the TEMP key until the setting is about 10°F (6°C) above the room temperature. The cooling equipment and fan should stop.
Move the system switch to OFF with the fan switch remaining at AUTO. The system and fan should be off.

Fan Switch

FAN AUTO: Normal setting for most homes. A single-speed fan turns on automatically with the air conditioner or furnace. A two-speed fan usually runs on high with the air conditioner and on low with the furnace.

FAN ON: The fan runs continuously. Use for improved air circulation during special occasions or for more efficient electronic air cleaning.

System Switch

COOL: The thermostat controls the air conditioning system.

OFF: Both the heating and air conditioning systems are off.

HEAT: The thermostat controls the heating system.

TROUBLESHOOTING

IF…	THEN…
Display will not come on.	•    Set the system switch to OFF; remove batteries; insert backward for at least five seconds to reset thermostat; replace batteries correctly. Display should come on.
	•    Make sure batteries are fresh and installed correctly.
Temperature display will not go lower than 45°F (7°C) or higher than 88°F (31°C) during programming.	•    The temperature setting limit has been reached. The setting range is 45°F to 88°F (7°C to 31°C).
Heating will not come on.	•    If the display is blank or displays bAt Lo, install fresh batteries.
	•    Check that the switch on the thermostat is set to HEAT.
	•    Check the system fuse or circuit breaker and replace or reset if necessary.
	•    If the temperature setting is higher than the current temperature, and SYSTEM ON indicator is lit, see the furnace manufacturer instructions.
Cooling will not come on.	•    If the display is blank or displays bAt Lo, install fresh batteries.
	•    In 2- or 4-wire installations, verify that the R-Rc jumper is installed.
	•    Check that the switch on the thermostat is set to COOL.
	•    Check the system fuse or circuit breaker and replace or reset if necessary.
	•    The thermostat has a built-in time delay on cooling. Allow five to ten minutes after changing the setting before the air conditioner starts.
	•    If the temperature setting is lower than the current temperature, and the SYSTEM ON indicator is lit, move the system switch from COOL to OFF for ten minutes.
	•    After ten minutes, return the switch to the COOL position. If the air conditioner comes on, the compressor could have reached its high limit temperature protection and shut down. If the air conditioner does not come on after ten minutes and the SYSTEM ON indicator is lit, see the air conditioner manufacturer instructions.
SYSTEM ON indicator is lit, but no heat is coming from the registers.	•    Allow time for the furnace to heat up and the fan to come on before checking for heat at the register. Check to make sure system on-time is set correctly according to the instructions in the Installation section.
Furnace or air conditioner cycles too frequently.	•    Check the system setting on the back of thermostat.
The system on-time is too short or too long.	•    Readjust according to the instructions in the Installation Section.
The thermostat current setting does not match the display temperature.	•    Check that the wiring hole in the wall behind the wallplate was plugged with insulation to prevent drafts that could adversely affect thermostat operation.
	•    It is normal for the current setting and display temperature to differ occasionally.
bAt Lo remains on the display after fresh batteries have been installed.	•    Remove batteries. Wait one hour. Install fresh alkaline batteries.

Home and Building Control Honeywell Inc.
1985 Douglas Drive North Golden Valley, MN 55422

Home and Building Control Honeywell Limited-Honeywell Limitée 155 Gordon Baker Road
North York, Ontario
M2H 2C9
Printed on recycled paper containing at least 10% post-consumer paper fibers.

Reference

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HONEYWELL T8112C Electronic Programmable Thermostats Installational Instruction

HONEYWELL T8112C Electronic Programmable Thermostats Installational Instruction