Should I Set My Thermostat Back During the Day in Jacksonville, Nc or Onslow County?

Smart thermostat used for scheduling

I read articles all the time and see posts from energy companies talking about setting a thermostat "back" when homes are not occupied to save energy. We get asked several times per week if there is any truth to this claim and the answer is, it depends.

Let's focus first on heating operation since it's currently 23 degrees outside in Jacksonville, Nc at the time this article is being written. I will say that when it comes to gas furnaces, there's no real electric savings by lowering the temp of the home when not occupied other than the blower motor will run less and save a little. The big savings with a gas furnace will be the gas itself. With an electric furnace such as what we often see installed in modular homes, yes setting the thermostat back will absolutely save you money on that electric bill. For the majority of you reading this you will likely have a heat pump and they are a little more complicated. Heat pumps are all electric and consume a large amount of energy when they start up, the less it starts and runs, the less electricity you use... most of the time. That rule is broken with full inverter driven or variable capacity equipment. Variable capacity units trend themselves to run longer run times at drastically reduced capacity so they don't start and stop a bunch, plus they use less than full capacity electricity 90% of the time to reduce energy costs. If you have a variable capacity unit or full inverter driven unit, leave the thermostat alone. Changing the thermostat on these units won't have a sizeable effect on your electric bill. With a single stage heat pump (most commonly found throughout Onslow County NC), setting the thermostat back can help you and it could also hurt you... Why?

Most heat pumps have a back up heat source referred to auxiliary or emergency heat. The back up heat is designed to pick up the slack of a heat pump when it gets really cold outside and the heat pump by itself would otherwise not keep up. Unfortunately your average thermostat doesn't know the outdoor temp so they are programmed to bring in the auxiliary heat anytime the desired temp is set to 2 degrees or more than the current home temp. Let's say that you prefer your home about 70 degrees and you have this type of system and you would consider turning the thermostat down to 65 during the day to save energy. When you get back home you have the thermostat set to 70 again and what happens, the unit turns on and energizes the auxiliary heat. In this scenario, you didn't save much, I promise. There are two methods to make the savings work even with single stage heat pumps. You can have an outdoor thermostat (it's no a regular thermostat) installed in series with the auxiliary heat that would lock it out so long as the outdoor temp is above a set point (typically we select 30 degrees). The other and in my opinion better option is to install a smart thermostat like the Ecobee (pictured above) where is uses wifi weather data and programming to control the auxiliary heat. I prefer the Ecobee over an outdoor stat for many reasons, but it will truly help you maximize savings if you really need to cut energy costs.

Finally we will discuss air conditioning setback. Setting air conditioning setback will save you money on that electric bill with most systems, again I'm going to exclude those variable capacity and inverter driven units here. We have to be careful though, because setting the indoor temp above 78 degrees can damage your equipment. The compressor of your ac is cooled by the refrigerant there is a very defined line of how warm that refrigerant can get before it starts damaging the compressor. When a properly working ac gets return air above 80 degrees, the compressor will operate at a higher than designed temp and lead to premature failure as well as very costly repairs.

That's really all there is to know about set back savings. As always if you have any questions or concerns, we are happy to hear from you and thank you for reading.