Programmable thermostats can be set to adjust the temperature setting according to a user's schedule. These thermostats typically have a digital interface that allows more precise temperature control and a wider range of options or features.
Programmable thermostats typically offer a number of programming options:
- Daily programming that allows one schedule to be used each day.
- Weekday/Weekend (5/2) programming that allows adjustment of timing for setbacks with different settings for weekdays and weekends, and with 5/1/1 programming that permits separate schedules for Saturday and Sunday.
- Full seven-day programming that permits a different setback schedule for each day of the week.
- Vacation Override, which allows temporary override of the programmed settings.
- Keyboard Lock, which prevents unauthorized changes to the preprogrammed settings.
- Low Battery Indicator indicates whether the battery used to hold the programmed schedule is low.
- An Energy Monitor that can keep track of how many hours the HVAC system has run for any selected time period.
- An Auto Season Changeover that automatically provides heat or cooling at the onset of the heating and cooling season.
- A Filter Change Indicator that goes on after a pre-set time period to remind when it is time to clean or replace the filter.
Programmable thermostats are readily available from various HVAC contractors/suppliers and home centers. The EPA maintains a list of ENERGY STAR® labeled programmable thermostats.
In order to receive the ENERGY STAR® label, thermostats must have at least two programs (one for weekdays and one for weekends), four temperature settings (two "normal" settings and two set-back settings for each day), a hold feature that allows users to temporarily override settings, and the ability to maintain room temperature with 2°F of desired temperature.
Limitations on use vary according to HVAC system type. For example, turning the heating temperature back in heat pumps will often cause the auxiliary electric resistance heating to turn on, defeating any potential energy gains. The digital interface for some electronic thermostats can be somewhat complicated to program, although manufacturers are making programming easier.