Programmable Thermostat Options

A programmable thermostat gives you the ability to set your home's heating and cooling temperatures to fit your family's schedule and reduce your total energy cost.  Since it controls the highest energy load in the home, this type of thermostat can be one of the best energy saving investments you can make.  These units have a variety of features to consider before selecting one that will work best in your home.

Ecobee Programmable Thermostat
Ecobee Internet Thermostat

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Programmable thermostat flexibility allows you to set a temperature for when you get up in the morning, another temperature when you leave for work, another when you return and another when you retire. Some models offer additional slots or programming intervals. Weekends can be scheduled to follow a different routine than week days.  IP based models can be programmed and monitored via the Internet and work well for second or vacation homes.

Types of Programs

There are basically four different types of programs found in programmable thermostats.  A brief description of each follows:

24-Hour Program - This is the simplest type of program as it repeats itself every day.  Wake, leave, return and sleep times and temperatures remain constant from one day to the next.

5 + 2 Program - The week is broken into two periods with one program schedule for Monday through Friday and a second for the weekend.

5 + 1 + 1 Program - Similar to the 5 + 2 program but allows Saturday and Sunday to have separate schedules.

7 - Day Program - A separate program is provided for every day of the week.   Sometimes these programs are set up as a 5+2 or 5+1+1 program to speed programming and then provide the ability to edit each day individually.  Another approach is to set up one day and use a "quick copy" feature to assist with programming.

Selecting the Right Programmable Thermostat

One of the easiest ways to determine which type of programmable thermostat will be compatible with your heating and cooling system is to remove the existing thermostat and count the number of wires connected to the base plate.  If there are only two wires, the thermostat is a simple battery operated, heat only thermostat.  No cooling system is controlled.

If there are five wires connected to the wall plate, the thermostat is a 24 volt circuit with one heating and one cooling mode.  The four wires shown here indicate the unit is battery operated.  This would normally run a central air conditioner and a separate gas, propane or fuel oil powered furnace.

Heat-Cool Thermostat Wiring
Click image to enlarge.
Eight wires would indicate the thermostat controls a heat pump using a 24 volt circuit.   However, not all wires may be used as connections for an outdoor thermostat are optional.

If the heat pump uses two stages and an outdoor thermostat an additional wire may be present.   It is best to confirm the type of thermostat required for these more complex systems from the wiring diagrams in the owner's manual.

Click image to enlarge.

If your home uses base board heat you may not have a low voltage thermostat.   Special high voltage programmable thermostats are available but require wiring into a 240 volt circuit.  These installations are best left to a licensed electrician.

Hold Features

Programmable thermostat hold features allow you to exit from the preset schedule to a fixed setting temporarily.  This might apply if you were to go on vacation or just wanted the temperature to remain constant for a couple of hours, the current program period or indefinitely.  Hold conditions are as follows:

Temporary Hold - Allows temperature to be adjusted for a short period of time.   This time period can be fixed, 2 hours for example, adjustable in 15 minute increments or terminate automatically at the beginning of the next program period.  It provides a temporary comfort adjustment without disabling the program.

Vacation Hold - Temperature is locked on a fixed setting for a specified number of days.  This allows you to return to a warm house in winter or a cool house in summer while reducing your energy costs when you are away.

Permanent Hold - Similar to vacation hold except the fixed setting is permanent.  The thermostat does not return to the programmed schedule until manually instructed to do so.

Other Features

One popular feature of the programmable thermostat is its ability to do auto change-overs.  Older thermostats require you to select the heating or cooling mode manually.  With auto change-over, the thermostat does this automatically which is very useful in Spring and Fall when the days are warm and the nights are cool.  Setting the "heat-to" temperature five to ten degrees below the "cool-to" temperature creates a dead band so the system will not cycle on and off and work against itself.

Some thermostats can track system run time.  This information can be useful for providing a change-out reminder for filters or UV air purification bulbs.   Fan hour run time is a more accurate indicator than calendar days. Plus, just having a separate reminder is helpful as it is easy to forget about that dirty filter behind the grate.

Programmable fans are also a useful feature.  The air handler fan circulates on and off randomly during periods when the heating or cooling system is off.   This helps balance temperature and humidity, improves air filtration and reduces pockets of stagnant air - especially during periods of low system run time when inside and outside air temperatures are similar.  Energy is also saved because the fan does not run continuously.

If you are a property manager, landlord or parent with young children you may find the keypad lockout and set point limiting features quite useful.  The keypad lockout disables some or all of the keypad control.   Different models use different techniques so check the owners manual for details.

Set point limiting is a way to lock in a maximum heating temperature or a minimum cooling temperature.  For example, if set to 76 deg. F. for cooling, occupants could choose any setting at or above 76 deg. F.   If set to 70 deg. F. for heating, occupants could choose any setting at 70 deg. F. or below.

Wireless and IP Remote Control

A wireless programmable thermostat uses a receiver to connect to the existing thermostat wiring.  Battery powered wireless thermostats are located in temperature sensitive areas throughout the home.  A hand held transmitter programs and controls each thermostat through a Wi-Fi connection.  This feature allows you to adjust the temperature from anywhere in your home.
IP Controlled Thermostat
Honeywell Wireless Thermostat System
IP Controlled Thermostat
Homewerks Radio IP Thermostat
IP (Internet Protocol) controlled thermostats connect to your home network with a Cat-5 Ethernet cable or wireless.  You can program and control each thermostat from any PC on your local network or from the Internet.   Many models have smart phone applications that allow you to make adjustments from anywhere.  Alarm features can email or text you when the temperature exceeds the limits you have set.

IP thermostats use an integral web server to connect with a host site that provides monitoring and control services - sometimes for a subscription fee.  Some models rely heavily on the remote site for full functionality while others provide it at the LAN (local area network) level.  Higher end units provide full functionality at the thermostat, local and remote levels.

Practical application for IP thermostats is in a second home, vacation rental or multiple small business locations.  Settings can be adjusted just prior to arrival.  You can also monitor temperature levels, change set points and be alerted when the temperature falls outside preset boundaries from anywhere.  This can prevent frozen pipes in winter or curb a mildew problem if the cooling system fails in summer.

Optimizing with a Home Energy Monitor

Tracking daily energy consumption with your home energy monitor gives you the benefit of knowing when a programming change to your thermostat saves you money, and equally important, when it does not.   Raising the temperature a couple of degrees in summer will reduce air conditioner run time and provide reliable savings.

However, lowering the temperature more than a couple of degrees in winter at night may cost you more if you have a heat pump.  Why?   When the command is given for the wake-up temperature to be met in the morning, the heat pump will most likely turn on auxiliary heat strips which can draw three to four times more power than the compressor.  This high power draw can negate the savings of a low overnight set point and is best addressed with an outdoor thermostat optimized for your home and weather conditions.

Another strategy to consider for managing this heat strip condition is to look for a programmable thermostat that can accommodate more than the four basic scheduling periods for awake, leave, return and sleep.  This technique will work if your system is set to energize the heat strips when a temperature increase of three or more degrees is requested.

Use one or two of the additional schedule slots to program the temperature to go up in two degree increments, 15 or 30 minutes before the wake temperature command is called for.  This way, the system sees only a two degree increase and will just use the heat pump to satisfy, unless the outside temperature is very low.  In that case, it is best to let the the heat strips come on as they are designed to do.  Heat pump compressor run times grow exceedingly long at low temperatures.

Logging energy consumption with your multi-point or circuit level monitor and correlating it with overnight low temperature readings will show you what the most efficient program settings should be.  Correlating, in this case, means to compare energy usage for those nights where the low temperatures fall within a five degree bandwidth.

The programmable thermostat controls the biggest energy consumer in the home.  Time is well spent tweaking the program and confirming the results with your home energy monitor system.   Just remember, once you have a program that minimizes energy cost while maintaining an acceptable level of comfort, that programmable thermostat will execute your plan week after week, month after month and year after year.

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