CT3451 Programmable Thermostat Owner's Guide

1 PREPARE FOR INSTALLATION

Check Table 1 to ensure compatibility with your system. If not compatible, return it to the retailer. Acquire necessary tools and items as described in Figure 1.

Figure 1: Required installation tools/supplies. This figure lists essential tools: a screwdriver, a hand or power drill with a 3/16 inch drill bit (if needed for holes), a wire cutter/stripper (if needed for wires), and a level (if needed for appearance).

^aNot compatible with any 120/240 volt circuit. Compatible with 2-wire Honeywell zone valves. Isolating relay required for zone valves that have a 3-wire thermostat connection.

2 REMOVE OLD THERMOSTAT

Test your heating and air conditioning systems before proceeding. Do not operate the cooling system when outdoor temperature is below 50°F (10°C) to avoid compressor damage.

CAUTION: Equipment Damage Hazard. Disconnect power at the furnace or main breaker/fuse box before installation.

Carefully unpack your new thermostat and wallplate. Remove the cover from the old thermostat; if it doesn't snap off, check for a locking screw. Loosen screws holding the old thermostat to the wallplate or wall and lift it away. Disconnect wires, using the provided labels to mark each wire with its old terminal designation. If there are only two wires, labeling is not required. Wrap wires around a pencil to prevent them from falling back into the wall, as shown in Figure 2.

Figure 2: Wrapping wires around pencil. This illustration shows wires passing through a wall opening, secured by wrapping them around a pencil to keep them from falling back into the wall cavity.

Replacing Clock With C or C1 Clock Terminals: If replacing a Honeywell Chronotherm® Thermostat, wires connected to C or C1 clock terminals should not touch each other to prevent transformer damage. Disconnect and wrap these wires separately with electrical tape. Ensure they do not interfere with the new thermostat.

Six or More Thermostat Wires: If you have six or more wires (excluding clock wires), you likely have a multistage system. This thermostat is not compatible. Visit www.honeywell.com/yourhome or call 1-800-468-1502 for compatible models.

Three Thermostat Wires: If you have three wires for heating only and can operate the fan with the Fan On switch, the thermostat works. For hot water (zoned) heating systems with three wires, an isolating relay must be installed by a contractor.

3 MOUNT WALLPLATE

IMPORTANT: Leveling the wallplate is for appearance only; the thermostat functions normally even when not mounted level.

Position the wallplate on the wall. Mark the two mounting holes. Figure 3 shows the mounting process:

Figure 3: Mounting wallplate to wall. This diagram illustrates marking mounting holes, drilling holes (3/16 inch for drywall, 7/32 inch for plaster/wood), inserting wall anchors, repositioning the wallplate with wires pulled through, and tightening mounting screws.

Remove the wallplate, drill holes, gently tap in provided anchors until flush, reposition the wallplate, pull wires through the opening, loosely insert mounting screws, level for appearance if desired, and tighten the screws.

4 WIRE WALLPLATE TERMINALS

All wiring must comply with local electrical codes. If unsure, contact a local HVAC contractor. Refer to the wire labels from your old thermostat.

Match the letter of your old thermostat wire with the corresponding terminal letter on the new thermostat (refer to Figure 4). Figure 5 shows connection methods: strip wires 5/16 inch (8 mm) for straight insertion or 7/16 inch (11 mm) for wraparound connections. Loosen terminal screws, slip wires beneath matching terminals, and tighten. Restrict all wiring to the shaded area in the center of the terminals.

Plug the wall hole with insulation to prevent drafts from affecting thermostat operation. The CT3451 is powered by 3 AA alkaline batteries and is adaptable to most 18 to 30 Vac heating/cooling systems. Figures 6 through 10 show typical system wiring diagrams.

Figure 6: Typical heat-cool system hookup with single transformer. Shows connections for a heat-cool system including transformer, heat relay, fan relay, and compressor contactor.

Figure 7: Typical heat system hookup with 2-wire, heat-only system. Illustrates wiring for a heat-only system with a transformer and relay/fan coil.

Figure 8: Typical cool system hookup with 3-wire, cool-only system. Depicts wiring for a cool-only system with a transformer and cooling contractor coil.

Figure 9: Typical heat-cool system hookup with two transformers. Shows a more complex heat-cool setup using two transformers, compressor contactor, heat relay, and dampers.

Figure 10: Typical single-stage heat pump system hookup. Details wiring for a single-stage heat pump system, including connections for compressor contactor, and heat/cool changeover valves.

5 ADJUST FAN OPERATION SWITCH

The fan operation switch (labeled fuel switch) is factory-set to 'F' (gas/oil fuel), suitable for most systems. For electric heat systems, set the switch to 'E' (electric). The 'E' setting ensures the fan turns on immediately with the heating equipment when the G terminal is connected, as shown in Figure 11.

Figure 11: Fan operation (fuel) switch. This image shows the fan operation switch with two positions: 'E' for electric heat and 'F' for gas/oil fuel.

6 MOUNT THERMOSTAT TO WALLPLATE

Slide the System switch to the Off position. Engage the tabs at the top of the thermostat with the slots on the wallplate. Press the lower edge of the thermostat onto the wallplate to latch it securely, as illustrated in Figure 12.

Figure 12: Mounting thermostat to wallplate. This figure shows how to attach the thermostat to the wallplate by aligning the top tabs and then pressing the bottom of the thermostat case to secure it.

7 INSTALLING AND REPLACING BATTERIES

The thermostat requires three AA alkaline batteries. Remove the battery door on the right side by pulling outward from the bottom (Figure 13). Insert batteries as shown. The thermostat displays a "bAtLo" message one to two months before batteries deplete. Batteries should be replaced annually to prevent leakage or system shutdown.

Figure 13: Installing batteries. This diagram shows the battery compartment and the correct orientation for inserting three AA alkaline batteries.

8 CUSTOMIZE YOUR THERMOSTAT

Your thermostat comes preset with common settings: Fahrenheit (°F), Gas or oil forced air furnace, and Aggressive algorithm control. You can change these settings.

Setting °C or °F Indication: Press the [Select] key to display the current setting, then press the [Up Arrow] or [Down Arrow] key to change it.

Setting Heat Cycle Rate: Press the [Select] key to display the current heat cycle rate (1, 3, 4, 5, 9, or 12 cycles per hour). Press the [Up Arrow] or [Down Arrow] key to select the desired rate from Table 2. All four setup steps must be completed to save changes.

Installer Setup: Press and hold the [Up Arrow] and [Down Arrow] keys simultaneously for over two seconds to enter Installer Setup. Use the keys to set the temperature setpoint to 52°F (11°C).

Control Algorithm: Press the [Select] key to display the heating/cooling algorithm default. Press the [Up Arrow] or [Down Arrow] key to change it to C1 (Standard control) or C3 (Aggressive control, default).

Current Configuration: Press the [Select] key to display the current configuration ('CC').

Exit Installer Setup: Press the [Select] key to save changes and return to normal operation.

^aHigh efficiency furnace (90+). ^bRefer to equipment manufacturer's instructions.

9 PROGRAM YOUR THERMOSTAT

The thermostat is preprogrammed with settings shown in Table 3. You can adjust these settings.

Wake: Time for comfortable temperature upon waking.
Leave: Energy-saving temperature when away.
Return: Comfortable temperature upon returning home.
Sleep: Energy-saving temperature during sleep.

IMPORTANT: Use your fingertip or a blunt tool to press keys; sharp instruments can damage the keyboard.

Setting Current Time and Day: Press [Select] twice to set the current time using the [Up Arrow] or [Down Arrow] keys. Press [Select] again to set the current day of the week. Press [Hold] to exit programming mode if using preprogrammed settings.

Setting Weekday Program: Slide the System switch to Heat or Cool. Press [Select] to set the time and temperature for Wake, Leave, Return, and Sleep periods using the [Up Arrow] or [Down Arrow] keys.

Setting Saturday and Sunday Programs: Repeat the programming steps (1-4) for Saturday and then for Sunday. Press [Select] after programming to display "End". Programming is complete.

Setting Temporary Temperature Hold: Press the [Up Arrow] or [Down Arrow] key to set a temporary temperature. This setting remains until the next program period. To cancel, press [Hold] twice.

Setting Indefinite Temperature Hold: Press [Hold]. The letters "Hld" will be displayed continuously. Press [Hold] again to cancel.

10 OPERATE YOUR THERMOSTAT

Displaying Temperature Setting: Press the [Up Arrow] or [Down Arrow] key once to display the present temperature setting. The thermostat reverts to displaying the current time and room temperature after approximately five seconds.

Setting Temporary Temperature Hold: Press the [Up Arrow] or [Down Arrow] key to set a temporary temperature. This setting remains in effect until the next program period. To cancel, press [Hold] twice.

Setting Indefinite Temperature Hold: Press [Hold]. The letters "Hld" are displayed continuously. Press [Hold] again to cancel. Press the [Up Arrow] or [Down Arrow] key to set the desired indefinite temperature.

11 SET FAN AND SYSTEM SWITCHES

Manually control fan and system settings using the switches at the bottom of the thermostat case (Figure 14).

Figure 14: Time/temperature display and System/Fan switches. This image shows the thermostat display area and the location of the System and Fan switches.

Fan Switch:
On: Fan runs continuously for improved air circulation.
Auto: Normal setting. Fan starts and stops with cooling equipment. In heating, fan is controlled by heating equipment, starting a few minutes after it turns on (or immediately if the fuel switch is set to 'E' for electric heat).

System Switch:
Cool: Controls the cooling system.
Off: Both heating and cooling are off.
Heat: Controls the heating system.

Heat and Cool Indicators: The [Flame symbol] indicates a call for heat. The [Snowflake symbol] indicates a call for cool. In programming mode, these symbols also indicate the System setting.

Minimum Off-Timer: The thermostat has a minimum off-timer to protect the compressor, preventing it from cycling on again for at least five minutes after turning off. A flashing [Snowflake symbol] indicates the minimum off-timer is in effect.

12 CHECK OPERATION AFTER INSTALLATION/PROGRAMMING

Heating System: Set System to Heat, Fan to Auto. Press [Up Arrow] to raise temperature above room temp; heating should start. Press [Down Arrow] to lower temp below room temp; heating should shut off.

Cooling System: Set System to Cool, Fan to Auto. Press [Down Arrow] to lower temperature below room temp; cooling should start. Press [Up Arrow] to raise temperature above room temp; cooling should shut off.

CAUTION: Compressor Damage Hazard. Do not operate cooling below 50°F (10°C) outdoor temperature. Allow compressor to remain off for five minutes before restarting.

Fan: Set System to Off, Fan to On. The fan should run continuously. Set Fan to Auto; the fan should turn off.

Backlighting: Press any key to light the display for approximately ten seconds.

TROUBLESHOOTING

ENERGY SAVINGS

PERCENT OF HEATING COSTS YOU CAN SAVE
Savings for once-a-day 10°F (5°C) decrease*:
6 to 8%
9 to 11%
12 to 13%
14 to 15%
16 to 18%

PERCENT OF COOLING COSTS YOU CAN SAVE
Savings for once-a-day 10°F (5°C) increase*:
7 to 9%
10 to 11%
12 to 14%
14 to 19%

*Your savings depend on home size, heat loss/gain, geographic location, frequency of temperature changes, and the range of temperature changes.

Limited One-Year Warranty

Honeywell warrants this product, excluding battery, to be free from defects in workmanship or materials under normal use and service for one (1) year from the date of purchase. Honeywell will repair or replace defective products within a reasonable time. To claim warranty, return the product with proof of purchase to the retailer or mail it, postage prepaid, to Honeywell Return Goods Dock 4, MN10-3860, 1885 Douglas Dr N, Golden Valley, MN 55422. For Canada, send to Honeywell Limited/Honeywell Limitée, Product Services ON15, 35 Dynamic Dr, Scarborough, Ontario M1V 4Z9.

This warranty does not cover removal or reinstallation costs. It is void if damage occurred while the product was in the consumer's possession. This is Honeywell's sole express warranty. Implied warranties of merchantability and fitness for a particular purpose are limited to one year. Some states do not allow limitations on incidental/consequential damages or implied warranty duration.

For warranty questions, write to Honeywell Customer Relations, 1985 Douglas Dr N, MN10-1461, Golden Valley, MN 55422. In Canada, write Retail Products ON15, Honeywell Limited/Honeywell Limitée, 35 Dynamic Dr, Scarborough, Ontario M1V 4Z9.