Honeywell CT50A Standard low volt Thermostat Instruction Manual
- June 9, 2024
- Honeywell
Table of Contents
Honeywell CT50A Standard low volt Thermostat
MODEL
- CT50A is for most gas and oil heating systems.
- CT51A is for most gas and oil heating or electric cooling systems.
- CT52A is tor most electric heating systems.
- CT53A is for millivoltage heating systems.
- Do-it-yourself models
YOUR HONEYWELL THERMOSTAT
Your new Honeywell CTS0A Heating Thermostat will replace most 15 to 30 V, 2-wire heating system thermostats. The CTS0A is suitable only for gas or oil heating systems (NOT for heating/cooling, heat pump, 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 pump 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 0 it off with a pencil or pen.
PREPARATION
- Check thermostat suitability for your home’s system by reviewing YOUR HONEYWELL THERMOSTAT section, above.
- Assemble tools required, as shown below.
THERMOSTAT FEATURES
- 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 [1 O C].
- Carefully unpack your new thermostat.
REMOVING OLD THERMOSTAT
(See 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 cover of 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 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 (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 screws holding thermostat base to subbase or wall, and litt away.
- Disconnect wires from 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 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
- ForCT50A: Connect each wire from the wall to either terminal on the back of the thermostat. Tighten the screws.
- For CT51A, CT52A: Connect wires from the wall to matching terminals on the back of the thermostat. Tighten the screws.
- ForGT53A: Connect wires to R and W for 750 rnV systems. Connect to R and Y tor 250 or 500 mV systems. Tighten the screws.
- Push excess wire back into wall and plug hole with non flammable 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 thermostat to 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 temperature setting lever if necessary to uncover the mounting hole.
- Recheck for level positioning, and firmly tighten both mounting screws.
- If installing CTSOA, CT51 A, 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. lf 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 the thermostat wires connected to it.
- On the CT50A, CT51A, or CT52A, set heat anticipator 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 systems 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 following instruction, disregard heating or cooling directions if not applicable to your system.
- Turn on power to the heating/cooling system.
- Observe system operation for at least one cycle on both heating and cooling. To observe:
- Place the system switch at HEAT position and fan switch at AUTO. More the temperature setting (ever 10 F [5.6 C] above room temperature. The heating equipment should turn on. A short warm-up period may be required bebre the system fan turns on.
- Place system switch at COOL position and move the temperature setting lever 10 F [5.6 C] below room temperature. The cooling equipment should turn on and the system fan should turn on.
- NOTE : Some systems have a time delay that can prevent operation up to 30 seconds.
- Turn the fan switch to ON. The system fan should turn on, and operate continuously. The system blower should continue to operate at any system switch or thermostat setting.
THERMOSTAT SETTING
- On CT51 A, 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
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.
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 reading.
- If the readings are the same, replace 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 thermometer has the same reading.
- Replace cover and put the system into operation.
References
Read User Manual Online (PDF format)
Read User Manual Online (PDF format) >>