Honeywell CT50A Thermostat
YOUR HONEYWELL THERMOSTAT
Your new Honeywell CT50A heating Thermostat will replace most 15 to 30 V, 2-wire heating system thermostats. The CT50A is suitable only for gas or oil heating systems (NOT for heating/cooling, heat pumps, or electric heating systems). Your new Honeywell CT51A heating/Cooling Thermostat will replace most 15 to 30 V, 4-wire, heating/cooling system thermostats. The CT51A is suitable only for gas or oil heating/cooling or electric cooling systems (NOT for heat pumps or electric heating systems). Your new Honeywell CT52A heating Thermostat will replace most 15 to 30 V. 4-wire electric heating system thermostats (NOT for cooling, heating cooling, heat pump, gas or oil systems). Your new Honeywell CT53A heating Thermostat is suitable for 250, 500, or 750 mV heating systems only.
- 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 a pencil or pen.
- Check thermostat suitability for your home’s system by reviewing YOUR Honeywell THERMOSTAT section, above.
- Assemble tools required, as shown below.
- 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 50F [10 C}. Carefully unpack your new thermostat.
THERMOSTAT FEATURES
REMOVING OLD THERM0STAT
- (See the illustration under step 4 to help you recognize the heat anticipator.) Make a note
- 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 anticipation adjustment mechanism. (See the last illustration under
- step 4 to help you recognize the heat anticipator.) Make a note here of that anticipator setting for future reference. The heat anticipator pointer, if adjustable will be set at one of a series of numbers representing the (electric current rating of the primary control in your furnace. Th 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 the subbase or wall, and litter 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 label it with the letter of the terminal designation to make reconnection to the new thermostat easier. Take care that these wires do not fall back into the wall opening.
- Retain the old thermostat for reference purposes until your new thermostat is functioning smoothly.
WIRE AND MOUNT THERMOSTAT
- For CT50A: Connect each wire to the wall to either terminal on the back of the to thermostat. Tighten the screws.
- For CT51A, CI52A: Connect wires from the wali to matching terminals an back of the thermo stat. Tighten the screws.
- For CT53A Connect wires to R and W for 750 mV systems. Connect to R and Y or 250 or 500 mV systems. Tighten the Screws. Push excess wire back into Walt 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 removes 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 the center of the bottom mounting hole. Move the temper-ature setting lever if necessary to uncover the mounting
- WIRE AND MOUNT THERMOSTAT (continued) Recheck for the level positioning and firmly tighten both mounting screws. 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.
- On On the CT50A, CT51A, or CT52A, set heat anticipation indicator at rating printed on primary control.
- Press the thermostat cover firmly onto the mounting clips.
CHECK OUT THE THERMOSTAT
- On the CT51A, the system switch controls as follows: HEAT-heating system only operateS. OFF-heating and cooling sys tems are disconnected. The coOL-cooling system only operates.
- The fan switch controls as follows: AUTO-fan operates when the heating or cooling system operates. ON-fan operates continuously
- NOTE: In the folowing instruction, disregard heating or cooling directions if it is not applicable to your system.
- Turn on the power to the heating/ cooling system. Observe system operation for at least one Cycie both heating and codling. to ODserve
- Place the system switch in HEAL position and switch at AUTO. More the temper-ature setting lever 10 F (5.6 G above room temperature. The heating equipment should turn on. A short warm-up period may
be required before the system fan turns on. - Place the system switch at the COOL position and mOve temperature setting over 10 F (5.6 C below room temperature.
- The cooling equipment should turn it on and the system tan should turn
- NOTE: Some systems have a time delay that can prevent opera-tion up to 30 seconds. Turn the fan switch ON.
- The system fan should turn on, and operate continuously.
- The system blower should continue to operate at any system SWitch or thermostat seting
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.
TROUBLESHOOTING
Our Honeywell thermostat requires little or no attention. Most problems can generally be traced to the folowing:
NOTE f your system is heating-only or cooling-only, disregard sections not applicable to your system.
| SYMPTOM | PROBLEM | CORRECTIVE ACTION | |
| No heat | System switch at OFF or
COOL Position. |
Move switch to HEAT position. | |
| Blown fuse or tripped circuit breaker. | Replace fuse or reset circuit breaker. | ||
| Furnace power switch is on OFF. | Switch to ON. | ||
| No pilot fla1T1e. | Religtil pilot rlame per furnace manufacture r’s instructions. | ||
| Improper connections to thermostat. | With Power to furnace OFF, tighten all mounting and terminal screws. Re pair broken wires. | ||
| Defective thermostat. (Here’s how you tell: Turn power to furnace OFF. Then remove the thermo stat from the wall. Dis connect wire from W termina\. Tum power to furnace ON. Touch W wire to R terminal. The thermostat is defective if the burner comes on.) | Exchange the thermostat (see Warranty). | ||
| Other. | Contact service technician for assistance . | ||
| Furnace turns on and ott | Burner-on period is too sho | Remove the thermostat cover and move the heat antici pator lever GOU N TERCLOCKWISE \ 7
one scale mark. Wait at least several hours to sta bilize. |
|
| Major swings in 1emp e rat u re (greater than 2 F [1.1 C] when out- side tern perature stable). | Burner – on is too long. | period | Remove the thermostat cover and move the heat anticipator lever CLOCK WISE 1′:. / one scale mark. Wait several hours for the system to stabilize. |
| SYMPTOM | PROBLEM | CORRECTIVE ACTION |
| Thermostat setting and thermometer reading disagree, | Thermostat is not level. | Recheck the thermostat position on wall. Use a bubble level to make sure it’s level. See step 4, |
| Thermostat affected by drafis or radiant heat. | Contact service technician to change u-,e location. The thermostat should be about
5 ft [1.5 m] above the floor and on an inside wall. |
|
| Thermostat is out of cali bration. | Contact a qualified service technician to recalibrate tt,e thermostat. | |
| Thermometer is out of calibration. | Recalibrate. See step 8. | |
| No cooling. | System switch in in OFF or HEAT position. | Move switch to C 00 L position . |
| Blown tu se or tripped circuit breaker. | Replace fuse or reset circuit breaker. | |
| Condenser switch (lo- cated outdoors) is turned OFF.
Improper connections to thermostat. |
Move switch to ON posi tion.
VVith power to furnace OFF, tighten all mounting and terminal screws. Re pair broken wires . |
|
| Detective thermostat. (Here’s how you tell: Turn power to cooling system OFF. Then remove the thermostat from wall. Disconnect wire from Y terminal. Turn power to cooling system ON. Touch Y wire to terminal
R. The thermostat is de fective if the compressor starts Some systems have a ti me delay, so allow at least 2-3 minutes.) |
Exchange the thermostat. See Warranty. | |
| Other. | Contact service techni
cian for assistance. |
RECALIBRATE THERMOMETER
If the thermostat set 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 the readings are 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.
Reference:
Download Manual:
Honeywell CT50A Thermostat User Manual
