How a Programmable WiFi Thermostat works.


How a Programmable WiFi Thermostat works.

A Programmable WiFi Thermostat is one that can be preprogrammed and controlled from anywhere on the planet where there is an internet connection. The thermostat has its own WiFi connection to all of a homeowner’s computers and handheld devices. To understand the benefits we need to first take a look at how a Programmable Thermostat works.

A Programmable Thermostat allows a home owner to save energy by programming lower or higher set points for the heating and cooling system at times when there is no one at home or everyone is sleeping. The mechanics of the device are as follows:


A thermistor or a resistor inside the thermostat measures the room temperature. Any change in the ambient temperature causes a change in the resistance of the metals present in the thermistor. A microcontroller within the thermostat converts the resistance changes into a digital temperature reading which is displayed on a screen.

In general, there are three methods to power a Programmable WiFi Thermostat. These include:

  • A rechargeable battery – used for charging when the thermostat is not calling for heating or cooling.
  • A non-rechargeable battery –  able to power a thermostat constantly.  However, an impulse relay system in the thermostat will allow a limited amount of power to be drawn. Thus, these thermostats do not require continuous applications of power to the coil in the relay.
  • The 24V AC supply operates via a high-tech circuit when the thermostat is not calling for heating or cooling, and uses the current flowing in the thermostat circuit when receiving a signal to apply heat. Power failures are taken care of with a battery back-up.

Several operating options are available to control a Programmable WiFi Thermostat, with basic ones only having one cycle that will run every day of the week. More advanced thermostats offer different options, such as:

  • 7-Day settings – useful for people who have busy schedules.
  • 4 Separate programs daily.
  • 5-1-1-Day settings – enables programs for weekdays and separate programs for Saturdays and Sundays
  • 5-2-Day settings permit separate programs for weekdays and weekends.
  • 1-Week settings are applicable for the entire week.
  • Weekend settings can be chosen arbitrarily for the desired days as per the user’s heating and cooling schedule requirements.

This is where a Programmable WiFi Thermostat has energy saving and comfort advantages compared to a non WiFi Thermostat model as the WiFi capability will allow overriding of the programmed settings in the event of a change in the homeowner’s schedule. This means that lower of higher set point durations can be extended if longer stays away from the home occur, or reduced when returning home sooner than expected.

Besides the separate programs for heating and cooling that are available for most Programmable WiFi Thermostats, many may feature a digital or manual switch to control the blower for air circulation. These can be operated even when there is no heating or cooling taking place. Many high-tech models run circulating fans for a brief period of 10-15 minutes without the prior running of a heating or cooling cycle in the previous hour. This reduces any possibility of ‘sick building syndrome’ setting in to the home.

Some Programmable WiFi Thermostats also provide an air filter change reminder. This utilizes the accumulated run-time of the heating/cooling system to enable it to display the status of the filter and remind the user when to change it. Receiving this information while out shopping is another convenient feature of a Programmable WiFi Thermostat.


Continue reading my Programmable Thermostats Review including How they work, What makes them green, FAQs, plus Tips and Tricks and please visit my Programmable Thermostats Store.

Please see our other review posts for this living green product: 

Programmable Thermostats – Best Features

What makes a Programmable WiFi Thermostat Green

FAQs for Programmable WiFi Thermostats

Tips and Tricks for Programmable Thermostats

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