Honeywell Home-CT52A-Thermostat-Featured



Honeywell Home CT52A Thermostat 

Honeywell Home-CT52A-Thermostat-PRODUCT


  • Check thermostat suitability tor your home’s system by reviewing YOUR HONEYWELL THERMOSTAT section, above.
  • Assemble tools required, as shown below.Honeywell Home-CT52A-Thermostat-FIG.1
  • Proper installation of your Honeywell thermostat will! occur if you follow instructions STEP-BY-STEP. it is recommended that as you read. understand and complete each step, you check it off with pencil or pen.


Honeywell Home-CT52A-Thermostat-FIG.2

  • Make certain that your burner/air conditioner where applicable) are working, especially if they have been inoperative for any length of time. If either does not work, contact your local heating/air conditioning dealer. Do NOT operate the air conditioning system if the outdoor temperature is below 50 F [10 C]
  • Carefully unpack your new thermostat.


  • Begin by turning off power to the heating/cooling system at the main fuse panel. Most residential systems have a separate switch box or circuit breaker for disconnecting power to the furnace.
  • Remove the cover of the old thermostat-cover normally snaps off when pulled firmly from the bottom.
  • If it resists, check for a screw that locks the COver on For CT50A, CT51A, or CT52A installation, before removing the old thermostat from the wall, look at it carefully to locate the heat anticipator adjustment mechanism. (See the last illustration under step 4 to help you recognize the heat anticipator.) Make a note here anticipator setting tor future of that reference. The heat anticipator pointer, if adjustable, will be set at one of a series of numbers representing the (electrical) current rating of the primary control in your furnace. The number will be one of the following: 2, 4, 8, etc., or 0.2, 0.4, 0.8, etc. If no heat anticipator/indication is showing, do not be concerned, move on to the next step.
  • Loosen the screws holding the thermostat base to subbase or wall, and lift away.
  • Disconnect wires from the old thermostat or subbase. If your thermostat has more than 2 wires, as you disconnect each wire, tape the end and iabel it with the letter of the terminal designation to make reconnection to new thermostat easier. Take care that these wires do not fall back into the wall opening.Honeywell Home-CT52A-Thermostat-FIG.3
  • Retain the old thermostat for reference purposes until your new thermostat is functioning smoothly.


Honeywell Home-CT52A-Thermostat-FIG.4 Honeywell Home-CT52A-Thermostat-FIG.5

  • For CT50A: Connect each wire from the wall to either terminal on the back of the thermostat. Tighten the screws.
  • For C151A, CI52A: Connect wires from the wali to matching terminals on the back of the thermostat. Tighten the screws.
  • For CTS3A: Connect wires to R and W for 750 mV systems. Connect to R and Y for 250 or 500 mV systems. Tighten the screws.
  • Push excess wire back into the wait and plug the hole with nonflammable insulation to prevent drafts from affecting thermostat operation.
  • Grasp the thermostat cover at the top and bottom with one hand.
  • Pull outward on the top edge of the thermostat cover until it snaps free of the thermostat base.
  • Carefully remove and discard the red plastic pin located above the mercury switch.
  • This pin protects the switch and bimetal assembly during shipment
  • Fasten the thermostat to the wall or vertical outlet box with a screw through the top mounting hole. See step 2 for hole location.
  • Place a bubble level or plumb line against the thermostat to find the level position. Start a screw in he center of the bottom mounting hole. Move the temperature setting lever it necessary to uncover the mounting hole.
  • Recheck for level positioning, and firmly tighten both mounting screws.
  • If installing CT50A, CT51A, or CT52A, make sure you have the current (anticipator setting) for your system. This is the number you wrote in the box in step 3. If you were unable to find the current draw for step 3. this information can be found printed on the primary control at the furnace. The primary control is usually a gas valve, zone valve,. or a relay or burner control box with thermostat wires connected to it.Honeywell Home-CT52A-Thermostat-FIG.6
  • On the CT50A, CT51A, or CT52A, set heat anticipator indicator at rating printed on Primary control.
  • Press the thermostat cover L firmly onto the mounting clips.


  • On the CT51A, the system switch controls as follows:
    • HEAT-heating system only operates OFF-heating and cooling systems are disconnected.
    • COOL-cooling system only operates
      The fan switch controls are as follows:
    • AUTO-fan operates when the heating or cooling system operates.
      ON-fan operates continuously.
      NOTE: In the following instruction, disregard heating or cooling directions It not applicable to your system.
  • Turn on the power to the Eraung cooling system.
  • Observe system operation for at least one cycle on 0oth heating or cooling.
  • Place the system switch in the HEAT position and the tan switch at AUTO.
  • More the temper ure setting lever 10 F (5.6 C] above room temperature.
  • The heating equipment should turn on. A short warm-up period may be required before the system turns
  • Place the system switch at the COOL position and move the temperature setting over 10 F 5.6 C below room temperature. e long equipment should turn on & and the system tan should
    NOTE: Some systems have a time delay that can prevent operation up to 30 seconds.
  • Turn the tan switch to ON. The system fan should turn n, and operate continuously. no system blower should continue to operate at any system switch or thermostat setting.


  • On CTS1A, place the system and fan switches at the desired settings for operation.
  • On all models, move the temperature setting lever to the desired temperature comfort level.


Your Honeywell thermostat requires little or no attention. Most problems can generally be traced to the following
NOTE If your system is heating-only or cooling-only, disregard sections not applicable to your system.

Honeywell Home-CT52A-Thermostat-FIG.7


Honeywell Home-CT52A-Thermostat-FIG.8

if the thermostat oct point and the thermometer reading do not agree, the thermometer may need recalibration. Follow the procedure below.

  • Remove the thermostat cover.
  • Set the cover on a table near an accurate thermometer.
  • After allowing 5 or 10 minutes for stabilization, compare the readings.
  • If tho roading is the same, replace the cover and put the system into operation.
  • If the readings are different, insert a hex-head wrench in the thermometer shaft and turn it until the thermometers have the same reading.
  • Replace the cover and put the system into operation.


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