by Sam Cassell
Cassell Brothers Heating and Air, Irmo, SC

"Make no mistake,
programmable thermostats
save money ..."

There is a lot of confusion about programmable thermostats. The most confusing piece of information is the statement “it’s cheaper to keep your house at the same temperature than to change the temperature up and down when you leave and return”. Usually this is untrue. It’s cheaper to turn down the heat or up the cooling when you are away. However, it can be true when heating with a heat pump if you do it manually. Here is why:

If I turn my heat pump back to the energy star setting of 62 while I am gone and cut it back up to 68 when I return, the thermostat will engage the electric heat strips because it thinks it has fallen behind. The heat strips use 3 or 4 times the energy that a heat pump normally uses, so you lose the savings you would have had for not heating the house all day.

If you use a programmable thermostat to bring the heat up it will not turn on the heat strips. Instead, it will take the last 20 times it came up to 68, average the times needed, then cut on that much earlier. This allows the thermostat to adjust to recent weather patterns.

Using the same process, the thermostat also solves this problem. Say I cut my cooling up to the energy star suggested temp of 83 while I am at work. When I come home and cut it down to 76 at 6 pm on a really hot day, it may take the air conditioning several hours to catch up. But the programmable thermostat is going to cut on as early as needed to have the temp at 76 at 6pm when I get home. If it needs to cut on 30 minutes early,  it will. If it needs to cut on 5 hours early, it will. Either way,

I never have to worry about setting it back too far. The new programmable thermostats are really easy to program. There are four time periods available for homes:

  1. Wake: This is when the first person up hits the floor; let’s say 6 am. This is the time you may want to spoil yourself a little, and maybe run the AC down a little more while showering, dressing, starting the day right. It is the shortest time period.
  2. Leave: This is when the house clears out and no one is home; let’s say 8 am. If following the energy star settings, the temp. can go to 62 in heating and 83 in cooling. But it’s okay; no one is home!
  3. Return: This is when you come home; let’s say 6 pm. Because of the averaging feature, you can set the temp. for what you like and it will be that temp. at this time, because it cut on earlier.
  4. Sleep:  This is for when we go to bed; let’s say 11-6. Most of us want it a little cooler when we sleep whether it’s in heating or cooling mode. In the morning, the thermostat changes back to Wake, so you don’t have to be the one to get up and change the thermostat.

For Saturdays and Sundays, use the Cancel period option and cancel the Leave and Return periods. You can also save more money by cutting off unused areas of the house at certain times. For a two story house with no bedrooms downstairs, for Sleep we cut it back to 83 and 62 again. Or maybe someone is home in the daytime but not upstairs, then we can also cut it back.

Make no mistake, programmable thermostats save money; an average of 3% per degree for the amount of time cut back. Double that for your business because you are gone 16 hours instead of 8.

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