Honeywell T87F Zone Thermostat Installation Instructions

Application

The T87F Thermostat provides 24 Vac single-stage temperature control for Honeywell Zone Control Panels. It operates heating or cooling systems and zone dampers in response to the thermostat's settings. The T87F is designed for use with the 137421 N or P Wallplate (included) or Q539A or B Subbase (ordered separately), depending on the specific application. Refer to Table 1 for detailed applications and specifications.

Mercury Notice: If replacing a control containing mercury in a sealed tube, do not discard in trash. Dispose of properly according to local waste management authority instructions for recycling and disposal.

Installation

When Installing This Product:

1. Read these instructions carefully to prevent product damage or hazardous conditions.
2. Disconnect the power supply before installation to prevent electrical shock or equipment damage.
3. Verify that the product's rating is suitable for your application.
4. Installation should be performed by a trained, experienced service technician.
5. After installation, use these instructions to check product operation.

Selecting Location

• Install the thermostat approximately 5 ft (1.5 meters) above the floor in an area with good air circulation and average temperature.
• Avoid installing the thermostat where it may be affected by: drafts, dead spots, hot or cold air from ducts, radiant heat from sun or appliances, concealed pipes, chimneys, or unheated/uncooled areas like an outside wall behind the thermostat.
• Handle the thermostat carefully as it is a precision instrument.

CAUTION: Electrical Shock Hazard. Can cause personal injury or equipment damage. Disconnect power supply before installation.

Mounting and Wiring

IMPORTANT: To prevent interference with thermostat linkage, keep wire length to a minimum and run wires as close as possible to the subbase. All wiring must comply with local codes and ordinances.

The T87F Zone Thermostat with a wallplate or subbase is used in zoned conventional single-stage heating or heating-cooling systems.

137421 Wallplate or Q539 Subbase

Replacement Application

1. Remove old equipment and dispose of it properly (see Mercury Notice).
2. Inspect existing wallplate or subbase wires for cracked or frayed insulation. Replace any damaged wires.
3. If wires are plastered into the wall, create a hole next to the wires to allow them to be pushed back into the wall later.
4. Proceed to Step 3 for New Installations.

New Installations

1. Run low voltage thermostat cable to the thermostat location if necessary.
2. Pull approximately 3 inches (76 mm) of cable through a hole in the wall.
3. Connect wires to the terminals inside the wallplate or subbase. Refer to Figure 1 and 2 or the zone control panel installation instructions for specific wiring diagrams.
4. Push excess wire back through the hole and seal any openings with insulation to prevent drafts that could affect thermostat performance.

137421 Wiring Cross Reference

5. Loosely fasten the thermostat wallplate or subbase to the wall using a screw through the left mounting hole (See Figure 3).
6. Adjust the wallplate or subbase to be approximately level and start the second screw through the right mounting slot. Do not tighten fully yet.

Figure 1. Wiring single ARD (power open) to thermostat.

Figure 2. Wiring T87F Thermostat and Q539B Subbase or 137421 Wallplate in independent zone.

IMPORTANT: An incorrectly leveled thermostat will cause deviations in temperature control. Ensure the wallplate or subbase is perfectly level using a spirit level as shown in Figure 4.

IMPORTANT: Do not overtighten thermostat captive mounting screws, as this can damage the subbase threads. Tighten the mounting screws securely.

T87 Thermostat Mounting

1. Before mounting the thermostat, adjust the Heat Anticipator as described in the Settings and Adjustments section.
2. Align the thermostat over the wallplate or subbase and tighten the three mounting screws.

Figure 4. Leveling wallplate or subbase before mounting T87F.

Settings and Adjustments

Temperature Selection

To set the desired temperature for each zone, turn the transparent dial on the zone thermostat until the desired temperature on the setting scale (top scale) aligns with the pointer.

System and Fan Switching

Q539A

The Q539A features System and Fan switches for controlling heating-cooling equipment and the zone one fan in multizone applications:

• System Switch: Controls system operation (Heat, Off, Cool).
• Fan Switch: Controls fan operation (Auto, On). In Auto, the fan operates based on the plenum fan control in heating and the thermostat in cooling. In On, the fan runs continuously.

To change switch positions, use your thumb and index finger to move the lever to the desired setting, aligning it directly over the selected function indicator mark.

Q539B

The Q539B provides System switching to control damper actuators in independent zones of heating-cooling systems.

NOTE: The Q539B System switch must be set to the appropriate position (Heat or Cool) corresponding to the system controlled by the thermostat.

• Heat: Damper opens when the thermostat calls for heat; damper closes when the thermostat is satisfied.
• Off: The thermostat is not calling for heat or cool; the damper remains in its last position (Open or Closed).
• Cool: Damper opens when the thermostat calls for cooling; damper closes when the thermostat is satisfied.

To change switch positions, use your thumb and index finger to move the lever to the desired setting, aligning it directly over the selected function indicator mark.

Heat Anticipator Adjustment

The T87F Thermostat has an adjustable heat anticipator. For correct system operation:

• When connected to a zone panel, set the heat anticipator to 0.1A.
• When connected to a damper in an independent zone application, set the heat anticipator to 0.4A.

Refer to Figure 5 for adjusting the heat anticipator.

Checkout

After completing installation, turn on the power supply and check thermostat operation as follows. For a complete checkout of the entire zone system, consult the zone control panel installation instructions.

CAUTION: Equipment Damage Hazard. Shorting across thermostat terminals of zone control panels can damage the heat anticipator. Check operation using these instructions.

IMPORTANT: To ensure accurate temperature control, avoid touching or breathing on the thermostat bimetal or thermometer.

Multizone System Checkout

Heating

1. Set System switches to Heat and Fan switches to Auto on TZ-3, EMM-3, EMM-3U, EZ-2, and EZ-4 thermostats. For MM-2 and MM-3, set the zone one thermostat subbase System switch to Heat and Fan switch to Auto.
2. Turn the Zone one thermostat dial 10°F (6°C) above room temperature to call for heat.
3. Turn dials on all other zone thermostats 20°F (6°C) below room temperature.
4. Observe that the zone one damper remains open and all other zone dampers close. (Dampers may take up to 30 seconds to fully open or close.)
5. Verify that the furnace starts immediately and the fan starts after a short delay.
6. To check zones other than zone one, turn the dial on one of the zone thermostats 10°F (6°C) above room temperature to call for heat.
7. Confirm that the associated zone damper opens.
8. Turn that zone thermostat dial 10°F (6°C) below room temperature; the damper should close.
9. Repeat steps 7-9 for each zone other than zone one.
10. Turn the zone one thermostat dial 10°F (6°C) below room temperature to end the call for heat.
11. Verify that the furnace shuts off and the fan stops after a short delay, unless another thermostat is calling for heat. All dampers should open unless configured to close on the MM-2 or MM-3 panel.

Cooling

1. Set System switches to Cool and Fan switches to Auto on TZ-3, EMM-3, EMM-3U, EZ-2, and EZ-4 thermostats. For MM-2 and MM-3, set the zone one thermostat subbase System switch to Cool and Fan switch to Auto.
2. Turn the zone one thermostat dial 10°F (6°C) below room temperature to call for cooling.
3. Turn dials on all other zone thermostats 10°F (6°C) above room temperature.
4. Observe that the zone one damper remains open and all other zone dampers close. (Dampers may take up to 30 seconds to fully open or close.)
5. Verify that cooling and the fan start.

IMPORTANT: To prevent compressor short cycling, a minimum off-time (e.g., a five-minute time delay) may be active before the compressor restarts after being turned off by the thermostat or when the system first receives power. This delay protects the compressor.

6. To check zones other than zone one, turn the dial on one of the zone thermostats 10°F (6°C) below room temperature to call for cooling.
7. Confirm that the associated zone damper opens.
8. Turn that zone thermostat dial 10°F (6°C) above room temperature; the damper should close.
9. Repeat steps 7-9 for each zone other than zone one.
10. Turn the zone one thermostat dial 10°F (6°C) above room temperature to end the call for cooling.
11. Verify that cooling and the fan shut off, unless another thermostat is calling for cooling. All dampers should open unless configured to close on the MM-2 or MM-3 panel.

Fan Operation

1. Set the Fan switch on the zone one thermostat subbase to On and the System switch to Off.
2. Verify that the fan runs continuously.
3. Move the Fan switch to Auto to control fan operation with the plenum fan control in heating and the thermostat in cooling.

Independent Zone Checkout

• Use the T87F with the 137421 N or P Wallplate for heat-only independent zone applications.
• Use the subbase only to control heating and cooling of independent zones. In this application, the T87F controls only the damper actuator; it is not connected to the heating or cooling equipment. A separate thermostat/subbase is required to control the heating and cooling equipment. Refer to the thermostat instructions for heating-cooling equipment checkout.

T87F Thermostat/Q539B Subbase Checkout

1. With heating equipment on and the Q539B subbase System switch set to Heat, turn the thermostat dial 10°F (6°C) above room temperature to call for heat. The damper should open.
2. NOTE: The damper may take up to 30 seconds to fully open or close.
3. Turn the thermostat dial 10°F (6°C) below room temperature; the damper should close.
4. With cooling equipment on and the Q539B Subbase System switch set to Cool, turn the thermostat dial 10°F (6°C) below room temperature to call for cooling; the damper should open.
5. Turn the thermostat dial 10°F (6°C) above room temperature; the damper should close.

T87F Thermostat/137421 Wallplate Checkout

1. With heating equipment on, turn the thermostat dial 10°F (6°C) above room temperature to call for heat; the damper should open.
2. NOTE: The damper may take up to 30 seconds to fully open or close.
3. Turn the thermostat dial 10°F (6°C) below room temperature; the damper should close.

Recalibration

The T87F is factory calibrated and typically does not require recalibration. If the thermostat appears to be out of calibration:

1. Ensure the thermostat is level and not exposed to radiant heat sources (sun, radiators, appliances).
2. Remove the thermostat cover ring to observe the mercury switch action.
3. After a five- or ten-minute off period (with the thermostat setting below room temperature), slowly raise the setting until the switch just makes contact. If the thermometer pointer and setting indicator read the same at this point, no recalibration is needed.
4. If recalibration is necessary: Set the dial a few degrees above room temperature and remove the cover.
5. Place the 104994 Calibration Wrench (ordered separately) onto the hex fitting under the bimetal coil. While holding the dial firmly, turn the hex clockwise until the mercury breaks contact (see Figure 6).
6. Set the dial to a low setting to allow the thermostat to cool down from hand heat and its own operation. Wait at least five minutes.
7. Slowly turn the dial until the pointers align.
8. Holding the dial steady, carefully turn the hex counterclockwise until the mercury switch moves to the heating contact end of the tube.
9. Recheck calibration, select the desired temperature, and replace the cover.

NOTE: When the T87F controls cooling, the heating calibration also calibrates for cooling.

Figure 6. Recalibrating T87F Thermostat.