[nn0wheremann]

Originally Posted by PompeyKing

Hello, I have been turning my AC up 2º when we leave the house for a little bit. Our thermostat will automatically lower the temperature back to the original setting after 2 hours. If we are going away for more than 4 hours, I will bump up the temperature and put the ac on hold.
A friend has said I am using more electricity by bumping up the temperature because it will take more energy to bring the temperature back down. I just don't know if that is true or not. I have picked up this habit from our days up north when we would turn down the heat when we left.
Any thoughts or facts would be greatly appreciated.

If you have a heat pump, leave the setting constant unless you are gone for a substantial period of time. If you have a regular air conditioner, bump it up 2 degrees while you are away for 2 or more hours. In TV our homes are well insulated. The AC will likely not run at all for quite a while. Bump it down when you get home if it is not comfortable. It may run longer, but this will also dehumidify the house while you are there. You get more comfort for your air conditioning dollar, and you might save $20 a month.

[tophcfa]

Interesting topic. When we are away for long periods of time we set the A/C at 81 and forget about it. When we are home we turn the A/C down to 73 before getting ready to go to bed and it stays there until we get up in the morning. When we get up we turn it up to 78. I have no proof to back this up, but I gotta believe that keeping the house at 78 during the hot sunny daylight hours saves money rather than keeping the house at 73 all the time? When we come into the house from being outside, 78 seems nice and cool to us.

[worahm]

You said...."When they are off, they use no electricity. The lower you set the temperature, the longer the unit will run, and the more electricity you will use. It is as simple as that. "

Maybe not.......There is a third condition you are ignoring.. An AC can draw 3 times as much current when it is starting then when it is running. So continuously starting and stopping your compressor will result in using significantly more power. Frequetly changing the inside temperature setting will cause the AC to start the compressor and cooling fan many more times then when you leave the AC set at one temperature.

If you are using a heat pump, it is even more important not to keep changing the control temperature. A heat pump is slow to recuperate. That is, it has to run a relatively long time to bring the inside temperature to the set temperature. In addition, the back-up aux. heater is frequently a resistive type heater, that uses a lot of electricity. Sort of like blowing air over a toaster. The aux. heater will typically come into play when the outside temperature is below 32 degrees and/or when the inside temperature is set to more then 3 degrees higher then the actual room temperature.

If you want to save money, replace your AC/heat pump with a unit that has a staged compressor. It will run as a low BTU unit when the outside temperature is mild and as a larger BTU unit when the outside temperature is extreme.

In our area of Florida, my staged heat pump runs as a 1.5 ton unit when the outside temperature is mild and as a 4 ton unit when the temperature is extreme. It typically runs as a 1.5 ton unit 84% of the time. Carrier recently introduced a heat pump that is infinetely varitable. That is, it will run on a wide variety of BTU levels to suit many different outside ambient temperatures. I've been living in Florida for 23 years. I have learned to leave my temperature controller set to 78 degrees in the summer and 72 degrees in the winter, except when I am away for more then 4 or 5 days. When I replaced my single stage heat pump with a two stage heat pump, I saved an average of $65.00 a month on my electric bill over the previous year when I was using a single stage heat pump.

[retiredguy123]

You make some good points. Yes, the AC unit uses more power to start, but I don't think more startups would significantly increase your electricity usage because it only takes a few seconds to start the unit, and you pay for electricity by kilowatt hours. I believe that almost all of the AC units in The Villages are single stage units. That is because they are cheaper to buy, and the electricity is relatively cheap. You can save a little money by doing the things mentioned in this thread, but, for most people, it's probably not worth the effort.

[stujake]

Originally Posted by retiredguy123

You are correct that the saving is not significant. I keep my thermostat set at 77 degrees all year round. My electric bill averages about 85 dollars per month. Although, a smart thermostat like Nest would save you a few dollars.

Has anyone figured out the payback time to cover the cost of a Nest Thermostat? What does it cost?

[stujake]

Originally Posted by lpkshop

Please keep in mind We had mold treatment and were told NEVER have your house higher than 75 degrees

It is not the temperature that causes a mold risk. It is the relative humidity going too high. When we were snowbirds, I had a humidistat installed so when we left for the summer months, we turned the humidistat to the recommended setting (if I recall correctly, it was 60% relative humidity) and set the thermostat to a higher temperature. If the relative humidity got too high, the air-conditioning went on until the relative humidity got down below the set level. The only problem we had was that some of our vitamins (D3 and Fish Oil) ended up sticking together. Other than that, no issues and saved a lot of energy cost.

[ffresh]

Originally Posted by theruizs

Want to know for sure? Keep doing what your doing for a month or a billing cycle, then leave it at a set temp for the next month/cycle.

On a different note, we monitor different areas of our house with thermometers and it is never a constant temp everywhere in the house. Our termostat (next to the Master BR) is set to 77 all the time. The temp in our main living area where we spend most of our time is then 75, and at the far end of the house it is 73. The Master BR is 75 or 76. So nowhere is it actually 77. No, I have no real point, just an observation.

That, unfortunately, is not sufficiently revealing (too many variables). The temperatures and humidity levels, to name two factors, will change in the subsequent month, as will other factors, e.g. oven cooking vs dining out, thus, raising the internal home temps, etc. I believe, to be useful, the test would need to be done under a more strictly controlled environment. Some of these "helpful" energy-saving devices come at a hefty price, as well (while we're on the discussion), necessitating a lengthy period to amortize the cost. Most folks are very familiar with what increases the cost of energy in the home; one of the biggest is hot water ---> raise the temp a bit and you'll save, likewise, for heating/cooling. What good does it do to spend $9.00, for example, on a sophisticated LED light fixture that illuminates an area that is being used for 30 mins total during a day/night. On the other hand, if the usage is such that the initial cost can be amortized in a short period = probably worthwhile. I don't believe it's any more complicated or requiring sophisticated monitoring devices than that, IMHO and, to be clear, I do love and appreciate technology but only for the convenience and value it supplies - not just for the sake of it.

Fred

[retiredguy123]

Originally Posted by stujake

Has anyone figured out the payback time to cover the cost of a Nest Thermostat? What does it cost?

Amazon has several types of Nest thermostats for about $200-$250. Apparently, you can even talk to some of them. I think the payback time would vary wildly, depending on your lifestyle. But, at least you'll have some one to talk to.

[Nordy]

I love how the energy dept. says ok to raise the temp. when away and lower it to 78 when you want cooling. 78 is cooling???and comfortable! I don't care what you say after that statement. If when up"North" it is ok to lower the t'stat when your away because your heating system can recover much quicker than your cooling system mostly because the heating system has to work on what's called sensible heat while your cooling system has to work on both sensible heat as well as latent heat,which is basically water vapor or humidity. I always leave my t'stat set where I am comfortable unless I am away for several days and the raise it to about 80.
forty years designing, seling and servicing a/c systems in Miami.

[Gpsma]

Really??...what does raising the thermostat a whole 2 degrees save you on electricity..25 cents?

Some people just cant stop “saving” money.

[Jimmy Lee]

Originally Posted by retiredguy123

Your friend is wrong. The amount of electricity you use is determined by the total run time for the AC unit. So, increasing the temperature setting for a few hours will reduce the run time and save money on electricity. You may want to consider buying a smart thermometer, like Nest, which is supposed to monitor your activities and automatically adjust the temperture settings to save electricity. I just leave my thermostat at the same setting all the time.

It's true that your AC will run less after you turn the thermostat to a higher set point but when you return and set the thermostat back to a lower set point the AC will have to run longer to get the temperature in your house back down to where it was. The overall difference in AC run time from turning the thermostat up and down compared to leaving it on HOLD will be small, unless you are gone for 8 hours or more. That's why a set-back thermostat can save money for someone who's away at work all day but not so much for a retiree making short trip away from home.

[Toymeister]

Originally Posted by worahm

You said...."When they are off, they use no electricity. The lower you set the temperature, the longer the unit will run, and the more electricity you will use. It is as simple as that. "

Maybe not.......There is a third condition you are ignoring.. An AC can draw 3 times as much current when it is starting then when it is running. So continuously starting and stopping your compressor will result in using significantly more power. Frequetly changing the inside temperature setting will cause the AC to start the compressor and cooling fan many more times then when you leave the AC set at one temperature.

You are right about the 50 millisecond start spike after that you are incorrect. If you want to see my AC power spike live on my phone I'll be happy to meet you at a rec center.

Again I have data from ten thousand reads of my power every second here in TV for years, not a theory.

[Topspinmo]

Originally Posted by New Englander

I'm sure many here won't believe this but My thermostat stays @82 degrees. Perfect temp for me.

Little too uncomfortable for me. I keep mine on 77 or 78 depending on humidity (raining mot or the day).

[Halibut]

Since there are interesting disagreements on thermostat settings, let me also throw this out as well.

My 18 month old A/C was leaking and when Munn's came out, the tech told me it was because we keep the temp at 70 degrees, which is too cool and stresses the compressor. This seemed preposterous to me.

It turned out that the unit had been installed incorrectly and something inside had been dripping for months, but is there any truth to the claim that setting the temp "too low" is bad for the unit?