Definition of programmable thermostat
A programmable thermostat adjusts the temperature of your home based on preset temperatures and times you’ve programmed into it. No more forgetting to turn up the AC before you leave the house for work; a programmable thermostat does the work for you by automatically keeping your home warmer during the day when you’re out and cooler in the evening when you’re sleeping.
Brief history of the thermostat
One of the first thermostats was created in the 1830s by Andrew Ure, an inventor who constructed a device with two metal strips that would expand and bend when the temperature increased. When the metal strips would bend, they would cut off the energy supply of the system thereby helping to regulate the temperature. Not too long afterwards, Warren S. Johnson invented the first electric thermostat that also had bi-metallic and a mercury switch which transferred the currents turning on the system. He ended up patenting his design and creating the Johnson Electric Service Company in 1885 to manufacture his product.
Around the same time, Albert Butz utilized a spring motor and pulley system to create the “damper flapper,” which would automatically open and close the flapper of coal furnaces to regulate the temperature. This invention is the origin of modern automated temperature control systems. Butz patented his design also and formed a company which was eventually purchased by a young engineer named Mark Honeywell, who went on to develop the first programmable thermostat. His programmable thermostat included a clock so one could preset the temperature for the following morning. In the 1950s, dial thermostats were introduced by Honeywell’s company and are still in existence today. In the 1980s, thermostats with digital displays and programmable functions entered the marketplace allowing for more control and energy savings for the consumer.
Understanding your programmable thermostat
One of the most useful features of a programmable thermostat is the ability to program the temperature based on the schedule and routine of your day. So, if you like to wake up to a slightly warmer temperature in the morning during the winter, then you can program your thermostat to achieve a higher temperature starting one to two hours before you awake. You can also program it to get progressively cooler in the evening to help lull you into a sound sleep.
The ability to program your thermostat helps you save money by allowing you to regulate the temperature during different times of the day and according to your schedule. Therefore, one of the first things you should do after you’ve installed your programmable thermostat is to track your daily weekday and weekend schedule. Once you’ve done that, you’ll know how best to program your thermostat for money-saving efficiency and automated comfort for you in your home.
Programmable thermostats are quite advanced and come equipped with microprocessors that allow you to store multiple daily and weekly temperature settings. There are a variety of programmable thermostats available with different advanced features and functions, but at the very least they will have the following basic four settings:
- Wake: If waking up to a slightly warmer environment is what you desire, then this is the setting where you’ll put in your “get-out-of-bed” temperature. You’ll want to set the wake time 30 to 60 minutes prior to your actual wake time to allow the system time to warm up your home.
- Leave: If your home will be empty for most of the day after you leave in the morning, then here is where you’ll set the temperature of your home to be slightly warmer on those summer days to save energy. You can set the “leave” temperature 30 minutes prior to when you actually leave for even more energy savings.
- Return: This is where you’ll want to set the temperature to start warming or cooling your home around the time the first person in your family arrives home.
- Sleep: This setting allows you to program your thermostat later in the evening, say 10:30 p.m., to a cooler temperature when most of your family has turned in for the night.
Programmable thermostats also have the option for manual override settings that won’t delete of interfere with your pre-programmed settings.
Is there mercury in a programmable thermostat?
Most electronic programmable thermostats sold today are mercury-free. If there is mercury in your thermostat, the sign for mercury, “Hg,” will be clearly labeled on the packaging.
Setting up the programmable thermostat
Before setting up your programmable thermostat, make sure you’ve put in new batteries. The next step is to follow the instructions in the manufacturer’s guide that came with your thermostat. When setting temperature and times, allow enough time for your HVAC system to achieve your desired temperature before you actually arrive home, go to bed, wake up, etc. If you’d like to have the option of programming different temperature settings for Saturday and Sunday, be sure to shop around for a thermostat that has that feature, otherwise those two “weekend” days will be treated as one with the same settings.
How frequently should my heating and cooling cycle on/off?
An air conditioner’s run time is known as a “cycle” and most systems have 2-3 cycles per hour. A typical cycle during mild weather is about 10-15 minutes. In extreme weather conditions, you can expect the cycles the run a bit longer. If your system is constantly cycling on and off, more than 2-3 times an hour, then your system is “short cycling,” which could indicate a problem with your unit.
If you’re wondering how long it should take for your AC system to cool your home, just know there are several factors which could influence the length of your unit’s run-time. For example, the outdoor temperature, the size of your home, the size of your AC system, and how warm you let the inside of your home get before it starts cooling down can all factor into how long it takes to cool your home. If you think your system is running longer than it should, call a professional, as an HVAC system which is running more than it should will have a significant impact on your utility bill.
What are the symptoms of a failing t-stat?
There are several signs to be aware of that could indicate a problem with your programmable thermostat:
- Thermostat is unresponsive
- Heater or AC won’t turn on
- HVAC system won’t turn off
- Room temperature doesn’t match setting on thermostat.
How do you calibrate a programmable thermostat?
If you suspect your thermostat is not reaching the temperature you’ve programmed it to, then you should perform a calibration to see if there really is a problem. To calibrate your programmable thermostat, do the following steps:
- Place an accurate thermometer right next to the thermostat. You can affix it to the wall with tape. Wait 10 to 15 minutes for thermometer to adjust.
- Check the temperature reading on the thermometer with the temperature reading on the thermostat. If it there is a difference, then you’ll need to calibrate the thermostat.
- Consult the manufacturer’s manual or scroll through the menu options on your thermostat to change the temperature offset.
- Adjust the temperature of your thermostat to match the reading on the thermometer. Your programmable thermostat will now use this new number as the actual temperature going forward.
Diagnosing problems – why is the programmable thermostat not working?
Troubleshooting.
If your programmable thermostat isn’t working properly, there are a few options you can try first before calling a professional.
- Check the batteries: Remove the front cover of your programmable thermostat and check or replace the batteries if necessary.
- Check the settings on your thermostat: Make sure you have the thermostat properly set to “heat” in the winter and “cool” in the summer.
- Remove dirt and dust: Make sure the exterior and interior of the thermostat are free of any dirt or dust. Gently wipe away any dirt or dust which could interfere with components on the inside.
- Check the circuit panel: Make sure the circuit panel doesn’t have a tripped breaker.
- Wire contacts: Remove the thermostat from its mounting on the wall and check the wire contacts to see if one has come loose.
- Check both heating and cooling: If your heat is working properly but you’re not getting any cold air, or vice versa, then the problem could be with the equipment and not the thermostat.
If none of these troubleshooting tips provide a solution, it may be time to replace your programmable thermostat. Check your warranty or if there have been any recalls for your product to see if you can get a free replacement.
Clear list of steps to operate the programmable t-stat
To set your programmable thermostat, follow these steps:
- To set the air conditioner for the weekdays, switch the thermostat to “cool” and select a program.
- Select “Weekdays” and then select the times and temperatures you would like for Monday through Friday. For example, if you want to raise the morning temperature to 76 degrees before you wake up 7:00 a.m., then set the time to 6:30 a.m., and the temperature to 76.
- If you leave your home at 8:30 a.m. on Monday, you can choose to set your thermostat to a warmer 78 degrees at 8:00 a.m.
- Upon returning home at 6:00 p.m., set the thermostat to 74 degrees starting at 5:30 p.m. to ensure your home is sufficiently cooled before you get home.
- For cooler temperatures when you sleep, choose the time you typically go to bed and the temperature you prefer. This program will now repeat itself for the other days of the week.
- To set the temperature for Saturday and Sunday, choose “weekend” and select the times and temperatures. Most programmable thermostats allow four settings per day for weekdays and two for the weekend. There are also thermostats available that allow individual settings for each day of the week as well.
How does a thermostat know the temperature?
Electric programmable thermostats use a “thermistor” to measure the temperature. A thermistor is an electrical resistor that changes its resistance with temperature changes. A microcontroller within the thermostat measures the resistance of the thermistor and displays that number to a digital temperature reading.
The cost of a programmable thermostat plus how much can I save a year with one?
Programmable thermostats are quite affordable with most models starting at around $40. With the ability to adjust the temperature based on predetermined times, which allow for optimum energy savings, you could save hundreds of dollars a year with this type of thermostat. Not only do they provide customized comfort based on your lifestyle, but they can also maximize your energy savings, nearly up 33% more than a manual thermostat would.
Should I upgrade to a programmable t-stat from my basic?
If you spend most of your time at home and don’t mind constantly getting up to adjust the temperature, then a manual thermostat should be fine. However, if you leave your house for long periods of time, want to save on energy and utility costs, and want the convenience of “setting it and forgetting it,” then a programmable thermostat is the choice for you. You may also want a “smart” thermostat. Click here to learn more about all of your options.