Thermostat settings & your AC motor?

[Orchidflower]

I did a search to see if anyone has posted anything on thermostat settings and either nobody has or I am missing them. Regardless, I was wondering how the electronics/weather pros here set their thermostats.

I did a study of our weather in Phoenix here by the hour and seems that the changes (drops and upswings in heat) are at: 7am; 10am; 3pm; 7pm; 10pm and Midnight. That is 6 (six) different changes thru the day for the therostat. There are many drops all thru the night till morning, but I figure if I set it for 12 Midnight it can stay where it is until 7 am.

My thermostat I can set at whatever time I want for the week and weekend, but is it hard on the a/c motor if I do 6 settings each day? I am moving the thermostat just one or two degrees at most each time.

I ask this in the interest of preserving my air conditioner's inner workings/motor as that is one HUGE $6-8K expense with the big Carrier air conditioners they use here in Phoenix, and I really want this one to last so long as I can, of course.

 

[travelover]

I'm missing something. Do you want the inside temperature to change constantly throughout the day in anticipation a change in load?

Are your electric rates different at different parts of the day, i.e. lower at night?

 

[rescueme]

I only have two settings (heat pump) that I change each year. I reside in one of the Mid-Atlantic States.

Winter? 68 degrees.

Summer? 74 degrees.

I don't fool with the system trying to make it "more efficient". I figured since I replaced/purchased a "high efficiency" unit a few years ago, it was its job, not mine..

 

[Animorph]

We just set it for 77 in the sumer and 73 in the winter, 75 for summer nights just before bedtime.

I suppose the less the heat pump turns on the longer it will last, so higher in the summer and lower in the winter should be good. Regardless of the outside temps.

 

[pimpmyretirement]

65 in winter, 75 in summer. As cold and as hot as I can tolerate.

 

[Orchidflower]

I'm missing something. Do you want the inside temperature to change constantly throughout the day in anticipation a change in load?

Are your electric rates different at different parts of the day, i.e. lower at night?

I'm trying to use minimal heat and cooling to decrease my electric bill; but I don't want to burn my thermostat out by having it switch 6 times a day. I'm just trying to beat the system if I can.

I know my electric bill they said was lower after 9 pm and before noon.
Phoenix has some various programs for electricity, and this is my current program; so, I try and do all my wash/drying in low peak time now, too.

 

[W2R]

I just leave my programmable thermostat on the defaults, and then adjust to whatever is comfortable at the moment.

This means that as the temperature drifts towards the defaults (85 in summer, 60 in winter, I think?) I have to be uncomfortable enough to actually get up from my chair to change the temperature if I want something warmer in winter or cooler in summer. I think my method saves a little energy, maybe. By the end of summer I am happy with temperature in the 80's, for example.

 

[Rustic23]

Summer we use 78 during the day and 74 at night. Winter is 68 during the day and 55 at night. It seldom gets that cold at night in the house. We also have a guest house and the AC runs for three hours at night between 2 and 5 in the morning, and the heater is set for 55 degrees in the winter. I figure in the summer it is good to pull the humidity out of the house once a day. (Texas about 60 miles north of Houston)

 

[Orchidflower]

Rustic: I know how hot it is where you are. You are a better person than I am if you can function with the temp inside being 78....wow...I wish I could. Too hot and clammy for me to think. How in the world do you do it?
But I have a girlfriend who lives with the setting of 83. I guess she and her husband like it like that, but her house smells from the dogs (I hope it's the dogs), too, but I think the stink would go away if she would up that temp some.
74 at night? That I can live with.
Am I the only one here who can actually notice the difference between 76 and 75 as a setting?

 

[ls99]

RE: the original post.

The AC motor(s) of the A/C do not care where you set the thermostat. Most motors have internal overtemperature protection and will shut down if overheated, then re-start when cooled. HVAC often has time delay built in to prevent short cycling.

HVAC motors do not have commutators or carbon brushes, nor sliprings with brushes to wear out.

Be aware that motors draw the most current at startup. Thus the more frequent starts the more you pay to the utility company.

Then there is the old problem of power factor, but for home appliances and of HVAC to correct for that is not economical. That you have to grin and bear. Besides it is not a huge factor in the costs. Which is why it is not worth to correct for.

 

[Orchidflower]

RE: the original post.

The AC motor(s) of the A/C do not care where you set the thermostat. Most motors have internal overtemperature protection and will shut down if overheated, then re-start when cooled. HVAC often has time delay built in to prevent short cycling.

HVAC motors do not have commutators or carbon brushes, nor sliprings with brushes to wear out.

Be aware that motors draw the most current at startup. Thus the more frequent starts the more you pay to the utility company.

Then there is the old problem of power factor, but for home appliances and of HVAC to correct for that is not economical. That you have to grin and bear. Besides it is not a huge factor in the costs. Which is why it is not worth to correct for.

Makes sense. I particularly got the "more frequent starts" = $$$$$. Thanks, Is99! That's what I was afraid of happening.

 

[travelover]

I'm trying to use minimal heat and cooling to decrease my electric bill; but I don't want to burn my thermostat out by having it switch 6 times a day. I'm just trying to beat the system if I can.

I know my electric bill they said was lower after 9 pm and before noon.
Phoenix has some various programs for electricity, and this is my current program; so, I try and do all my wash/drying in low peak time now, too.

I can't see how the thermostat schedule would affect the unit's life (within reason) but if you can take advantage of lower electric rates at certain times, you could over cool or over heat during the cheaper rate period in anticipation of a load change from the sun's position in the sky. The more thermal mass your house has, the more effective and comfortable this would be.

 

[Texas Proud]

I can't see how the thermostat schedule would affect the unit's life (within reason) but if you can take advantage of lower electric rates at certain times, you could over cool or over heat during the cheaper rate period in anticipation of a load change from the sun's position in the sky. The more thermal mass your house has, the more effective and comfortable this would be.

On your first point... I agree... my old house had an 18 YO system and from what I could tell, the starts and stops did not shorten the life... heck, I want it to start and stop when it gets to the temp I want... or not...

 

[Moemg]

I keep my thermostat at 75 most of the year and in the winter I turn it off for a few months and air out the house .Living in Southwestern Florida .

 

[Rustic23]

We have ceiling fans in every room except the dining room, and no one ever uses the dinning room. We even had two installed in the kitchen. Actually we can go with it set at 80 until about Jul. and Aug. then we throw caution to the wind and set it down to 78.

 

[JOHNNIE36]

We have a heat pump system and I set the desired temp at 78 during the hotter months. Since February I normally had the system "off". Last week or so it has started to warm up and the humidity is increasing so the unit is now "on". About December when it start to get cooler, I will set the thermostat at 70. Hardly ever put it above that. In the mornings during the "winter" we will turn on the fireplace insert to take the chill off. That insert alone will keep the heat pump from coming on.

Haven't heard anyone mention a "humidistat". Quite common in Florida with the high humidity. Used mostly if you are gone for a long period of time and want to protect the house. With the humidistat, you set the humidity at 60% (as desired) and the thermostat at 90 degrees. The A/C system will then operate based on the humidity and not temperature. You wouldn't care if it got warm in the house, you just don't want the humidity affecting anything.

 

[Dimsumkid]

Best way I've saved on AC bills is by having a whole house fan and using dehumidifiers. It's important to remove the humidity from the air as much as possible. Open up all the 2nd floor windows to bedrooms in use and it's like sleeping in a wind tunnel. Also kept the blinds closed during the days. Many potential buyers (just sold the house) were surprised how low our electric bills were in the summer months and overall for the year. We seldom used our AC and we had 2 units.

 

[Texas Proud]

Best way I've saved on AC bills is by having a whole house fan and using dehumidifiers. It's important to remove the humidity from the air as much as possible. Open up all the 2nd floor windows to bedrooms in use and it's like sleeping in a wind tunnel. Also kept the blinds closed during the days. Many potential buyers (just sold the house) were surprised how low our electric bills were in the summer months and overall for the year. We seldom used our AC and we had 2 units.

Interesting.... where do you have your dehumidifier How is it set up.. whole house like and AC or whatever?


This morning my wife was complaining about how 'hot' it was.... I said 'it is 75 degrees... that is not hot'... but the humidity had crept up to over 60% and it was 'muggy'...

 

[Dimsumkid]

Interesting.... where do you have your dehumidifier How is it set up.. whole house like and AC or whatever?


This morning my wife was complaining about how 'hot' it was.... I said 'it is 75 degrees... that is not hot'... but the humidity had crept up to over 60% and it was 'muggy'...

The dehumidifer is in the basement. It's a stand alone 40 pint unit, but really endless since I punctured the container opening and have a hose connected directly to the basement drain. This is in a 2 story, 2 layer true brick georgian style. If it's 80 and humid your skin feels clammy, but 80 and dry, you feel comfortable. Of course, with AC there's a dehumidifier built into the unit, but running a separate dehumidifier makes the AC unit run less to remove moisture from the air and in the end should save you more money.