Honeywell T8624C Programming Thermostat User Manual

Honeywell T8624C Programming Thermostat 

INTRODUCTION

The T8624C,D Chronotherm III Programmable Fuel Saver Thermostats provide automatic control of multistage heating/cooling systems and offer users the highest standard of comfort and convenience available with energy savings.

•  Different schedules may be selected for weekdays, Saturday and Sunday.
• Can be programmed in hand (with batteries installed) or on wall to provide up to four temperature settings per day.
• Large digital clock (liquid crystal display) indicates continuous time, day, current period and room temperature.
•  Adaptive Intelligent Recovery™ brings room temperature to programmed temperature at programmed time, maximizing comfort and energy savings.
• Temperature control program maintains temperature within 1° F of setpoint.
• Temporary program override available by using:
  • WARMER and COOLER keys.
  • SKIP next period key.
  • CHANGE to last period key.
•  HOLD TEMP key provided for indefinite program override (vacation/holiday).
•  Installer self-test and time delay override save installation time.
•  SYSTEM light-emitting diode (LED) indicates system is energized.
• Models available with automatic or manual heat/ cool changeover.
•  Batteries included provide power to maintain clock and memory during power failures.
•  Switching subbase with wiring terminals included.
•  Powered directly from control transformer, requiring an extra (24V) wire to thermostat.
•  Fan operation switch to select either independent or direct thermostat control of fan in heating included on back of select models.

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

TRADELINE® MODELS

• TRADELINE models (see Table 1) are selected and packaged to provide ease of stocking and handling and also maximum replacement value.
• LIGHT-EMITTING DIODE (LED): SYSTEM LED
• lights during thermostat ON cycle.
• VOLTAGE RATING: 15 to 30 Vac.
• CURRENT RATING: 1.6A maximum total per stage.
• OPERATING HUMIDITY RANGE: 5 to 90 percent relative humidity, noncondensing.
• OPERATING AMBIENT TEMPERATURE RANGE:
• 40° F to 110° F [4° C to 43° C].

Specifications

• SETPOINT RANGE: 45° F to 88° F [7° C to 31° C].
• CALIBRATION: Self-calibrating thermostat and thermometer to ±1° F.
• SHIPPING TEMPERATURE: -20° F to +120° F [-29° C to +49° C].
• CYCLES PER HOUR ADJUSTMENT:
• Heating: First stage of 2-stage heat models—fixed at 3 cph. Second stage of 2-stage heat models or heat stage of single-stage heat models—factory-set at
• 6 cph; field-adjustable to 1,3,6 or 9 cph.
• Cooling: Factory-set at 3 cph (not field adjustable); minimum off-time of five minutes.
• FINISH: Beige matte with decorative brushed metal faceplate or Premier White™.
• DIMENSIONS: Thermostat (mounted on subbase)—7 in. [178 mm] long, 5-5/16 in. [135 mm] high, 1-3/4 in. [44 mm] deep. See Fig. 1 for subbase dimensions.
• TYPICAL KEYPAD: See Fig. 2.

ACCESSORIES:

• TG586A Locking Cover.
• TG512 Versaguard™ Universal Thermostat Guard

TABLE 1—TRADELINE MODELS.

Thermostat Model Number	Stages		Changeover Type	Switching		Application
	Heat	Cool		System	Fan
T8624C	2	1	Auto	HEAT-AUTO-COOL-OFF	ON-AUTO	Multistage
T8624D	2	2	Auto	HEAT-AUTO-COOL-OFF	ON-AUTO	Multistage
T8624D	2	2	Manual	HEAT-OFF-COOL	ON-AUTO	Multistage

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 number, or specify

• Model number.
• Number of heat and cool stages desired.
• System, fan switching desired.
• Application.

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

•  Your local Honeywell Home and Building Control Sales Office (check white pages of your phone directory).
•  Home and Building Control Customer Satisfaction
• Honeywell Inc., 1885 Douglas Drive North
• Minneapolis, Minnesota 55422-4386 (612) 951-1000

In Canada—Honeywell Limited/Honeywell Limitee, 740 Ellesmere Road, Scarborough, Ontario M1P 2V9. 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.

T8624 Subbase mounting dimensions in in. [mm].

Typical thermostat keypad

Selection/Application

The T8624 Thermostat uses the latest microelectronic design and control technology to provide home and building owners with the highest level of comfort available and optimal energy savings in a package that is easy to use and easy to live with. The following section is a guide to selection and application of the best thermostat to meet individual needs.

PROGRAMMING
Does the thermostat selected accommodate the customer’s daily schedule, lifestyle or work schedule?

IF NEW CONSTRUCTION APPLICATION, CONSIDER:

•  Equipment type (see manufacturer specifications).
  • Staging required.
  • System switching required.
  • Fan switching required.
•  Control wiring—number of conductors required to operate equipment and thermostat.
• IMPORTANT: The T8624 requires an additional conductor to transformer common to provide continuous 24V power for thermostat operation.

IF RETROFIT/REPLACEMENT APPLICATION, CONSIDER:

•  Equipment requirements.
• Staging (heat stages, cool stages).
• System switching (manual: HEAT-OFF-COOL; automatic: HEAT-AUTO-COOL-OFF). Emergency heat for heat pump application not provided on T8624.
• Fan switching; does fan come on automatically from thermostat on cooling only (typical gas/ oil heating), or on call for cool and heat (typical electric heat with single speed fan)?
• Existing wiring —Are there enough conductors to operate the equipment and the thermostat? Can a new cable be pulled?

IMPORTANT: The T8624 requires an additional conductor to transformer common to provide continuous 24V power for thermostat operation.

SECURITY
Does the thermostat selected provide access to programmming and the override features that will best suit the application? The choices are

SINGLE-STAGE HEAT PUMPS

• If home/building owner has a single-stage heat pump, one option is to use a T8624C or D (see Fig. 8).
• The T8624C is a two-stage heating, one-stage cooling programmable thermostat. The T8624D is a twostage heating, two-stage cooling programmable thermostat.
• What both thermostats have in common is separate
• W1 and W2 (first and second stage heat) terminals. In both cases, the W1 can be used for changeover in heating.
• For single-stage compressor applications (both firststage heating and first-stage cooling energized through the Y terminal), simply jumper Y1 and W1.
• Note that the recovery algorithm of the T8624 may cause the compressor to cycle on and off during recovery.
• Although the cycle rate for the first stages of heat and cool are set for hot water systems, the second stage of the T8624 must be adjusted.
• Turn the cycle rate adjustment screws to the hot water setting on both the T8624C and D to achieve the cycle rate appropriate for heat pumps.
• If changeover is utilized in the cooling mode, apply a normally closed relay.
• The above application should be used only on singlestage heat pumps

Installation

NEW INSTALLATION
Run cable to a hole at the selected wall location for the thermostat, and pull about 3 in. [76 mm] of wire through the opening. Color-coded, 18-gauge thermostat cable with at least one conductor for each wiring terminal is recommended. Good service practice recommends selecting cable with one or two more conductors than the immediate application requires.

MOUNTING SUBBASE
IMPORTANT: Before mounting, set the system switch to the OFF position.

COMPATIBILITY
The T8624 Thermostats will replace most heating/ cooling system thermostats. As long as ac power is continuously available to the transformer, the thermostat will be compatible with any low-volt control system.

IMPORTANT: The T8624 requires an additional conductor to transformer common to provide continuous 24V power for thermostat operation.

WHEN INSTALLING THIS PRODUCT…

•  Read these instructions carefully. Failure to follow them could damage the product or cause a hazardous condition.
•  Check the ratings given on the product to make sure the product is suitable for your application.
•  Installer must be a trained, experienced service technician.
•  Allow thermostat to warm to room temperature before operating.
•  After installation is complete, check out product operation as provided in these instructions.

LOCATION
Install thermostat and subbase about 5 ft [1.5m] above the floor in an area with good air circulation at room temperature. Do not install thermostat where it may be affected by:

• drafts or dead spots behind doors, in corners or under cabinets.
• hot or cold air from ducts.
• radiant heat from sun or appliances.
• concealed pipes and chimneys.
• unheated (uncooled) areas such as an outside wall behind the thermostat.

REPLACING AN EXISTING THERMOSTAT
Turn off thermostat power at furnace or boiler. A two transformer system may require turning off two switches or disconnects. Remove any existing wallplate or subbase from wall. To avoid miswiring later, label each wire color with the letter or number on the wiring terminal as the wire is removed.

WIRING

• All wiring must comply with local electrical codes and ordinances.
• Disconnect power before wiring to prevent electrical shock or equipment damage.
• The shape of the terminal barrier permits insertion of straight or conventional wraparound wiring connections.
• Either method is acceptable.
• Push excess wire back into the hole, and plug the hole with nonhardening caulk, putty or insulation to prevent drafts from affecting thermostat operation.
• NOTE: Restrict wiring to the recessed area surrounding the terminals to assure thermostat/subbase contact.
• Refer to Figs. 6-8 for typical hookups of subbase and thermostat.

ADJUSTING CYCLE RATE

• To customize the thermostat cycling performance to various types of heating equipment, cycle rate adjustment screws are provided on the back of the thermostat to provide optimum room temperature control.
• NOTE: Most applications will not require a change in cycle rate.
• The room air temperature will normally vary slightly from the comfort temperature setting with the cycling of the furnace or air conditioner.
• The heating cycle rate of this thermostat is factory-set for gas/oil warm air heating. The cooling cycle rate is factory-set and cannot be adjusted. The heating cycle rate can be adjusted by turning one or both cycle rate adjustment screws located on the back of the thermostat.
• In multistage heat systems, the cycle rate adjustment applies to the highest stage of heat only. Screws should be backed out about one-half to one turn, or be turned in until tight.

TIME/TEMPERATURE CONVERSION (SOME MODELS)
The display readout may be converted between 12 and 24 hour clock or °C and °F using screws 2A and 2B as indicated

FAN OPERATION OPTION SWITCH (SELECT MODELS ONLY)
Select models include a fan operation option switch on the subbase that is visible before the thermostat is mounted on the subbase. The switch should be in electric heat position for electric heating systems that do not have independent fan control.

INSTALLING BATTERIES

• Three AAA alkaline batteries are included to provide backup to prevent program loss in case of power outage. Install batteries in back of thermostat
• Without battery backup, the program will remain about 30 seconds in event of power loss.

IMPORTANT: When batteries are first installed, the display will flash 1:00 PM and 32°. The temperature will stay at 32° F until the thermostat is powered from the system wiring. When the batteries are low, the display will flash REPL BAT. Homeowner will have 20-30 seconds to install new batteries after removing old batteries from back of thermostat. After 20-30 seconds, it will be necessary to reprogram. REPL BAT indication will disap

T8624C 2-stage heat/1-stage cool thermostat with HEAT-AUTO-COOL-OFF system and AUTO-ON fan switching.

T8624D 2-stage heat/2-stage cool thermostat with HEAT-AUTO-COOL-OFF system and AUTO-ON fan switching.

T8624D 2-stage heat/2-stage cool thermostat with HEAT-OFF-COOL system and AUTO-ON fan switching; auto fan on heat and cool; convertible to auto fan on cool only.

T8624D 2-stage heat/2-stage cool thermostat with HEAT-OFF-COOL system and AUTO-ON fan switching; auto fan on heat and cool; convertible to auto fan on cool only.

Cycle rate adjustment.

POWER OUTAGES
Backup batteries will hold the programming and keep the display on during most power outages. Once the power is restored, the system will resume normal operation. After replacing the batteries, reprogramming will be necessary.

MOUNTING THE THERMOSTAT
With system switch set to OFF, hang the thermostat on the tabs at the top of the subbase (Fig. 11A). Swing down and press on lower edge until thermostat snaps in place  Open cover and tighten the captive mounting screws

SETTING DAY AND TIME

• Restore 24V power to the thermostat. When power is applied to the thermostat, the display will read 1:00 PM and room temperature. It will go off for a few seconds, then begin to flash on and off. Set present day and time.
• Press
• Press to set the current day. Each press of the DAY key advances the display one day.
• Press TIME to set the current time.
• If the display will not come on:
• Check the mounting of the thermostat to the subbase.
• If loose or misaligned, remove thermostat and reinstall on the subbase, making sure it is firmly attached.
• Check to see that heat or cool system power is on.
• Check voltage between R and C; it should be 24 to 30 Vac.

HEATING
Move the system switch to HEAT and the fan switch to AUTO. Press WARMER key until the setting is about 10° F [6° C] above room temperature. Heating should start (both stages if multistage), and the fan should run (may be a short delay on forced air systems). Press COOLER key until the setting is about 10° F [6° C] below room temperature. The heating equipment should shut off, followed by the fan.

NOTE: On an AUTO changeover thermostat, the cooling temperature must be set at least 3° F [2° C] above the heating temperature, or display will flash

COOLING
Move the system switch to COOL and the fan switch to AUTO. Press COOLER key until the setting is about 10° F [6° C] below room temperature. The cooling equipment and fan should start (both stages if multistage). Press WARMER key until the setting is about 10° F [6° C] above room temperature. The cooling equipment and fan equipment should stop. NOTE: On an AUTO changeover thermostat, the heating temperature must be set at least 3° F [2° C] below the cooling temperature, or display will flash.

FAN
Move the system switch to OFF, and the fan switch to ON. The fan should run continuously. When the fan the switch is in the AUTO position, the fan operates directly with the thermostat call for cooling and also with the

CHECKOUT

Programming the Thermostat

TROUBLESHOOTING

Glossary

Comfort temperature
The temperature desired when active and occupying the home.

Energy-saving temperature
The lower (heating) or higher (cooling) temperature that allows savings on heating and cooling costs when asleep or away. Also called the setback (heating) or setup (cooling) temperature

Period	Start Time	Temperature
		Heating	Cooling
WAKE	6:00 AM	70° F	78° F
LEAVE	——— No program ————
RETURN	——— No program ————
SLEEP	10:00 PM	60° F	78° F

Period key
One of the four keys—WAKE, LEAVE, RETURN or SLEEP—to check or program the start time and temperatue for a time period.

Preprogrammed schedule
This is the schedule programmed into the thermostat at the factory. It sets a night program that provides energy savings when homeowner sets no program, or if personal program is lost for any reason. The program, which is the same for all days of the week, is:

Program
The times and temperatures homeowner sets to define the comfort and energy saving periods for each day schedule.

RETURN—The time period that the house is at a comfortable temperature for family activities in the evening before bedtime.

SLEEP—The time period that the temperature can be set back (winter) or set up (summer) for energy savings because the family is sleeping. It can be set to start at the family’s normal bedtime. Often the SLEEP program is set only for the heating season so family members can sleep cool in the cooling season

Weekday program schedule
The schedule of WAKE, LEAVE, RETURN and SLEEP period start times and temperatures programmed to run
Monday through Friday.

Recovery
The time when the thermostat operates the heating or air conditioning equipment to return the home from the energy saving temperature to the comfort temperature. The thermostat starts the recovery period early so the home will be at the comfort setting by the time the homeowner has chosen.

Saturday program schedule
The schedule of WAKE, LEAVE, RETURN and SLEEP period start times and temperatures programmed to run on Saturdays.

Setback
Reducing the temperature in the home for a set period in heating for energy savings. The lower temperature is the energy saving temperature.

Setup
Raising the temperature in the home for a set period in cooling for energy savings. The higher temperature is the energy saving temperature.

Setpoint
The thermostat temperature setting the homeowner selects. The thermostat turns the heating or cooling equipment on and off to maintain this temperature at the thermostat location until another temperature setting (setpoint) goes into effect.

Sunday program schedule
The schedule of WAKE, LEAVE, RETURN and SLEEP period start times and temperatures programmed to run on Sundays.

SYSTEM light
This light glows whenever the thermostat is calling for heating or air conditioning.

Time period

• One of four program periods: WAKE, LEAVE, RETURN and SLEEP available with the thermostat. One period begins when the previous program period ends:
• WAKE—The time period that the house is at a comfortable temperature while the family gets up and gets ready to leave for work or school. This is the only period that must contain a time and temperature.
• LEAVE—The time period that the temperature can be set back (winter) or set up (summer) for energy

Honeywell

• Home and Building Control
• Honeywell Inc.
• Honeywell Plaza
• P.O. Box 524
• Minneapolis, MN 55408-0524

REFERENCE

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Honeywell T8624C Programming Thermostat User Manual

Honeywell T8624C Programming Thermostat User Manual