Honeywell Chronotherm III Thermostat

Posted by: Mas Broto
Last Udated:
Honeywell Chronotherm III Thermostat

Honeywell Chronotherm III thermostat was made around 1977 by Honeywell, Inc. On the front of the thermostat, there is a clock, a thermometer, and two levers (one red and one blue) for setting the temperature. For heating, the left (blue) lever sets the lower temperature for when the clock hits a blue pin, and the right (red) lever sets the temperature for when the clock hits a red pin.

When you put the red and blue program pins into the clock, it turns on or off the furnace to heat the house to the setting.

The Honeywell thermostat worked with a bimetallic strip and a mercury tube. When the temperature dropped, the bimetallic strip moved in one direction, and when the temperature went up, it moved in the other direction. This movement moved the mercury into a tube. When the mercury moved to one side or the other, it opened or closed a circuit inside the tube.

The fact that thermostats are in almost every home in the 21st century makes it hard to see how many years of new ideas, industrial design, and engineering went into making them so common.

Homeowners could set the Honeywell Chronotherm III thermostat to a certain temperature, which would open a damper to the furnace, making the fire bigger and heating the house. As technology improved, thermostats could connect to gas lines, use electricity, be set to turn on at a certain time, heat and cool in one mechanism, and even connect to the internet.

Honeywell Chronotherm iii Troubleshooting

The Honeywell Chronotherm III thermostat shows “-AC” where the current temperature used to be. The thermostat is used to control both the air conditioner and the heater, and the problem happens in both the “heat” and “cool” settings.

According to the owner’s manual, some models will show the message “- AC” when they are running on the backup batteries. I would make sure that the thermostat has 24-volt power.

How to Reset Honeywell Chronotherm III thermostat

You can’t reset all the Honeywell thermostat functions at once, so you’ll have to reset each set by hand.

  1. Open the cover panel of your Honeywell Chronotherm III to see the buttons for programming.
  2. Push the “Day” button over and over again to set the clock to a certain day. If you want to start over with the programming for each day, just start with one.
  3. Press the right “Period” key and hold it down for three seconds. For example, to reset the “Leave” or “Return” programmed time, you would press and hold the “Leave” or “Return” button. When the time is reset, the temperature will no longer be shown on the screen.
  4. Repeat the steps for each day you want to start over with the program.
  5. When you’re done, press “Run Program” to manually run the system. You can also start making plans for your new program schedule if you want to.

Honeywell Chronotherm III Replacement

The Honeywell Chronotherm III had only four wires connected R, W, Y, and G. You may be wondering if you need just a basic thermostat or a specific thermostat that will work with your HVAC system.

What is the correct replacement for the Chronotherm III thermostat? There are a lot of thermostat brands, like Honeywell, that can be used to replace it. How fancy you want the thermostat to be is up to you.

Honeywell has thermostats that range from cheap to high-tech, with Wi-Fi and smartphone access. Nest is also a top brand, and Ecobee is also a top brand.

For some homeowners, it can be hard and frustrating to troubleshoot and find the correct replacement for the Honeywell Chronotherm III thermostat. No matter what problem you’re having with your HVAC system or any of its parts, it’s often a good idea to call a professional HVAC technician.

If you have problems with your Honeywell Chronotherm III thermostat all the time, you might want to buy a new one. Over time, this equipment wears out, and a new thermostat model may have many benefits. In fact, a new thermostat could save you a lot of money on your energy bills because your old one might have been wasting energy.

mas broto avatar

Mas Broto

Have been in the heating and air conditioning (HVAC) industry for over 20 years. He is person that will grow and thrive to learn more about the HVAC industry throughout his career. Mas Broto is also a blogger, who's dedicated to bringing you the best knowledge to get ahead in the game of life.

Related Posts