Programmable Thermostat

Programmable thermostat is used extensively in medium to high end HVAC systems. The common thermostat that is used in the air conditioning control system before the advancement of microchip and electronic is a simple mechanical bi-metallic thermostat that contact before a set temperature is achieved and disconnect after a set temperature is achieved.

A dead band of few degrees known also as hysteresis is set to prevent chattering of contact that can cause damage to the load that is being controlled. This simple thermostat has greater tolerance and is not accurate. The tolerance can be as high as +/-5°C.

The advancement and the reduction of microchip price have enabled the HVAC industry to use better electronic control that is more accurate, more user friendly and efficient. Products that incorporate Liquid crystal Display, 7 segment LED display, LED, keypad/touch screen and better industrial design have been developed.

The programmable thermostats that have been certified by the government have many features that allow you to save energy. When used properly, it can save your utility bills and provide better comfort to you. If you are looking for one, make sure that the thermostat has the ENERGY STAR mark on it.

Features Of Programmable Thermostat 

  • 7-Day Programmable Schedule feature will enable you to program the ON/OFF time, temperature setting, mode of operation and other important features. This will enable the proper use of the air conditioner capacity. For instance, when there is no one at home, the set temperature will be set higher during that duration to reduce the electricity consumed.
  • Night Setback feature will increase the set temperature (if in cooling mode) after certain hours gradually as one will not need that much cooling capacity once you are sleeping. This feature is sometimes incorporated into the programmable schedule.
  • Thermostat accuracy of +/- 2°C or better to ensure the comfort of the occupants in the house.
  • 24 Hour Clock is a must with liquid crystal display, keypad/touch screen, backlighting that enables you to operate it in the dark.
  • Holiday feature option need to be there. During holidays, the set temperature will be set higher(in cooling mode) or cycling mode to reduce the capacity and hence the consumption of electricity.
  • Actual Outdoor or Indoor temperature display option is another good feature to have.
  • Diagnostics feature that enables you to find out the reason the air conditioner is not working properly. It could be a missing sensor, high pressure tripping, low refrigerant, etc.
  • Air Filter Change indicator after a certain time of operation. This reminder is a good feature to alert you that it is time to change or clean your filter.


When installing the thermostat, remember to install the sensor in a location where the air circulation is good. Usually the sensor is located at the panel itself. Do not install it under direct sunlight, doorways or windows as this will cause inaccurate reading of the room temperature.

Related Links

Smart Thermostats
Here are some of the latest thermostats in the market that incorporate Wi-Fi and mobile apps that can be controlled from iOS and Android based phones and tablets. Keep abreast with the technology by using these gadgets.

Air Conditioning Thermostat
Read more about the types of thermostats available in the market. 

Air Conditioner Controllers
See the basic functions of air conditioner controllers in a room air conditioner unit. 

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