DIY Home Improvement Forum banner
1 - 19 of 19 Posts

·
Registered
Joined
·
69 Posts
Discussion Starter · #1 ·
I'm wondering if it's better to leave the A/C on all day or turn it off and have it try to catch up in mid-afternoon when it's hottest? :huh:
 

·
DIY Hack
Joined
·
1,306 Posts
I looked into this same thing a few years ago and everything I read says it's better to shut off and turn back on when you need it. I think the theroy was that A/C units are most effieicent when they run all out, rather then coming off and on in short spurts all day. I just program my thermostat to come on about 30 minutes before we usually get home, and I have it go off late at night, then come back on for a couple hours in the morning. My electric bills seem to be much lower than some of the ones I hear my neighbors crying bout
 

·
Banned
Joined
·
17,158 Posts
I have mine set at 76 when away, 72 when home, and 70 at bed time. EPA guidelines state 76-78 when home, and 81 when away. Those do not work everywhere, so you have to adjust according to where you live.
 

·
DIY Hack
Joined
·
1,306 Posts
I have mine set at 76 when away, 72 when home, and 70 at bed time. EPA guidelines state 76-78 when home, and 81 when away. Those do not work everywhere, so you have to adjust according to where you live.
70 degrees?

You mid-west guys must have sides of beef hanging in your livingrooms:wink:
 

·
A Little Of Everything
Joined
·
2,428 Posts
I'm wondering if it's better to leave the A/C on all day or turn it off and have it try to catch up in mid-afternoon when it's hottest? :huh:
That depends on several factors.

We have a big brick house, built in 1928. All the walls are still plaster. I've super-insulated & all that junk.

We have a programmable thermostat, but I found that it's best - and most economical - to just set our thermostat at one temperature, and leave it. Winter or summer, it's the same story.

Also, we happen to have about 10 very large trees that provide a lot of shade in the summer.

Our house is 4400 square feet, and our total monthly utility bill is $110 per month (budget plan, so the same amount every month).
 

·
A Little Of Everything
Joined
·
2,428 Posts
I have mine set at 76 when away, 72 when home, and 70 at bed time. EPA guidelines state 76-78 when home, and 81 when away. Those do not work everywhere, so you have to adjust according to where you live.
Dang - that's gotta be quite a shock to walk in from outside these past few days!
 

·
Registered
Joined
·
3,630 Posts
electronic thermostat?

if it is :wink: just like in the winter ......setting it higher in the summer to maintain the unoccuppied temp 78F "LEAVE" then set "RETURN" for 70F as the sun swings on the windows during the day the unit will cycle to maintain 78F and as the RETURN time nears you coming home it will cycle up to give you 70F at that time then till SLEEP time/temp kicks in.most stats run Wake/Leave/Return/Sleep adjustments with hour and temps to,the lower the LEAVE is to the RETURN in temp setting the quicker it will recover but then it is also maintaining that temp during work hours $$$$$ :huh: take into consideration the sun banging the house hitting sills floors walls...if it is minimal your saving right there...
 

·
Banned
Joined
·
17,158 Posts
70 degrees?

You mid-west guys must have sides of beef hanging in your livingrooms:wink:
Actually not that cold, unless the humidity level in the house drops below 47%. Our basement stays around 66-68 during the Summer. Right now it is 95 with a feels like of 106.

Now, Winter time our thermostat is set at 60 for bedtime & away, 68 when home until bedtime. My electric & gas come out at about the same costs all year. Gas is on a budget pay, electric is low rates, so it evens out around $68 most of the year, $86 at the highest. Gas because it is Ameren, comes out at January around $112.
 

·
Registered
Joined
·
689 Posts
i've thoroughly run and tested my a/c at several thermostat settings over the last few years here in very HOT texas. it definitely helps to set the temp up a few degrees during the day when you are gone and let it catch up when you get back. there are tons of theories surrounding this and i'm sure a lot of factors that effect overall performance, but i think the main idea is that having your a/c run continuously as opposed to a lot of cycling off and on is better. plus, it's cooler in the evening when you turn it back on so it doesn't work as hard to cool. i would recommend no more than a 3-4 degrees temperature difference. i set mine to 79 and 82 which always seems to work out to about 77 - 80 actual temperature in the main area of the house (thermostat location is never perfect and you will have fluctuation).
 

·
Registered
Joined
·
511 Posts
I set mine at around 78-79 when I leave in the a.m. and usually keep it there when getting home, though I'll turn on the ceiling fan.
If I don't turn it down to around 73 at bedtime, it won't cycle and I wake up with a wet pillow.:mad:
 

·
Registered
Joined
·
873 Posts
80 is good enough for me. then I have small fan on low. I hate ceiling fans, feels like your head is in a buzz saw and always blowing down your neck.

In winter 68 is warm enough. wear a sweater if cold. Long as the nose and ears arent cold. cuts utility bills both ways.

Here if you shut ac off in day have to open windows, humidity in house is worse than temp, hard on food keeping, furniture and house. turn it on and leave alone.
 

·
uva uvam vivendo variafit
Joined
·
641 Posts
I looked into this same thing a few years ago and everything I read says it's better to shut off and turn back on when you need it. I think the theroy was that A/C units are most effieicent when they run all out, rather then coming off and on in short spurts all day. I just program my thermostat to come on about 30 minutes before we usually get home, and I have it go off late at night, then come back on for a couple hours in the morning. My electric bills seem to be much lower than some of the ones I hear my neighbors crying bout
My understanding is that an AC unit that only runs for a short time will not run long enough to reduce the humidity. And this is why they say oversizing the units on your house is as bad as undersizing them.

Similar to you, I let my AC run up to 78 during the day and drop to 72 about an hour before I get home. My ground flooring is a stained concrete slab, which helps keep the downstairs a little cooler. I've tried running up the temp upstairs higher than 78, but it takes a long, long time to cool off.
 

·
Household Handyman
Joined
·
2,480 Posts
I'm glad someone threw the humidity factor in here. I have never understood how here in SW GA. we can have temps breaking 100's for days on end at this time of year, and they say the humidity is 100% at mid-day also. If it ain't raining, how can we have 100% humidity? My mind tells me that with 100% humidity I should be underwater. I have a programmable thermostat also. It's programmed to set the temp to 78 when I leave home in the a.m., then go to 76 just before I get home about 4-ish p.m. At 8 p.m. it goes to 73 to cool it down before going to bed, and it's still hot. At 11 p.m. it does go to 70 degrees until the morning setting of 78. Believe me, 70 degrees with 100% humidity is not as cool as I would like it and NO you cannot hang beef in here. My unit is serviced yearly and has had no work performed on it since new. Just another advantage (?) of living in SW GA.
 

·
Registered
Joined
·
19 Posts
My HVAC guys says it is best to leave it at a reasonable temperature and not to turn it way down/up. The reason is the system has to warm or cool not only the air but the structure(walls, floor, furniture, etc..). This is like getting into a hot car in the summer and turning the air on full blast. It takes awhile for the seats and inside to cool even though the air is cool. I would stick to minor adjustments throughout the day. Maybe 10 degree changes. Also, I have a heatpump and it is designed to run longer. You don't get that immediate heat coming from the vents in the winter time. I can't change the temperature very quickly in my house.
 

·
Registered
Joined
·
47 Posts
I typically run 85F when I'm out, and 78F when I'm home. Then again I live alone and am naked or in boxers most of the time. Come night time, I turn on a fan, and point it at me. Though when friends/family stop by, I cover my shame, and lower the temperature to 72ish. In the winter time, I'm the opposite; I keep the house around 60F, and keep blankets around the house.
 

·
Registered
Joined
·
617 Posts
When they say that it's 100% humidity, they mean that the air is holding as much water vapor as possible-- not that the air is completely composed of water vapor.
 
1 - 19 of 19 Posts
Top