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# Home A/C length of cooling time

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• Jun 24th, 2016 7:36 pm
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[OP]
Member
Feb 10, 2015
333 posts
Hamilton, ON

## Home A/C length of cooling time

I was wondering what everyone is usually keeping their home A/C temperature set on and also how long does it take to cool house down for each degree of Celsius.
For example if current house temperature at 2pm in the house is 25C what time will it be when house temperature gets to 23C?

Thanks
28 replies
Nov 29, 2011
1078 posts
Grimsby
I do know that (my house anyways), cooling 2 degrees for example, takes significantly longer than heating 2 degrees.

I recently heard that you don't want your AC to be able to drop the temperature too quickly and the reason was pretty interesting. Since your AC also dehumidifies the air in your home, if your AC is cooling too quickly, it's not dehumidifying as much and the end result can be a house that is cool, yet relatively humid - which can be extremely uncomfortable.
The worst part about prison was the Dementors. - Michael Scott

My Basement Reno Project
Sr. Member
Apr 8, 2010
784 posts
toronto
another reason is that it's easier for on an a/c to run for longer periods of time, rather than cycling on and off quickly.
[OP]
Member
Feb 10, 2015
333 posts
Hamilton, ON
yes cooling does take longer but do you have example how long does it take to cool for each degree....
Oct 20, 2011
1112 posts
Mississauga
There are so many variables such as:

Size of home
How many floors
Size of unit
Seers rating
How energy efficient the home is.
How many windows.
How many people are in the home.
Which way your house faces.
If the blinds are open or closed.
What is the humidity level in the home.
I can go on and on.

In my home it takes about 1/2 hour to go down one degree F.
Nov 29, 2011
1078 posts
Grimsby
Stribor40 wrote: yes cooling does take longer but do you have example how long does it take to cool for each degree....
I would guess for my house that making up a 2 degree difference (celsius) could take 1 to 1.5 hours?
The worst part about prison was the Dementors. - Michael Scott

My Basement Reno Project
Deal Guru
Dec 10, 2004
12316 posts
Kanata
Stribor40 wrote: yes cooling does take longer but do you have example how long does it take to cool for each degree....
Too many factors to give you solid numbers. House size, AC size, room where thermostat is located, register locations, outside temperatures, etc, all that varies too much.
[OP]
Member
Feb 10, 2015
333 posts
Hamilton, ON
well my AC runs 2 hours to cool house down for 1 degree
May 23, 2009
2836 posts
Mississauga
MyDream1 wrote: There are so many variables such as:

Size of home
How many floors
Size of unit
Seers rating
How energy efficient the home is.
How many windows.
How many people are in the home.
Which way your house faces.
If the blinds are open or closed.
What is the humidity level in the home.
I can go on and on.

In my home it takes about 1/2 hour to go down one degree F.
goofball wrote: Too many factors to give you solid numbers. House size, AC size, room where thermostat is located, register locations, outside temperatures, etc, all that varies too much.
I wholeheartedly agree. I have temperature and humidity sensors spread around my house and the outdoor temperature is enough to mess up any pattern.

My best guess is 45mins for 0.5C cooling. Heating is closer to 30mins for each 0.5C.
Deal Expert
Aug 22, 2011
35601 posts
Center of Universe
Mine averages 1.5hr per deg as per my historic data measured from my Ecobee t-stat (based on average temp calculated from the main tstat and sensors in the living room and bedrooms upstairs).
Member
Apr 10, 2006
391 posts
Mine took a good whole 5 hours to go down from 25 to 23. And after that, it cycles on after 5 minutes of shutting down and runs for about 30 minutes. Note that this was just based on last Sunday or Monday's heat. But once it hits about late evening, it kinda doesn't go on and off as much as its starting to cool down outside.

Just the feeling of it running for hours makes my head spin with cents and dollars flying out the window. LOL.
[OP]
Member
Feb 10, 2015
333 posts
Hamilton, ON
vanpatrick81 wrote: Mine took a good whole 5 hours to go down from 25 to 23. And after that, it cycles on after 5 minutes of shutting down and runs for about 30 minutes. Note that this was just based on last Sunday or Monday's heat. But once it hits about late evening, it kinda doesn't go on and off as much as its starting to cool down outside.

Just the feeling of it running for hours makes my head spin with cents and dollars flying out the window. LOL.
Thats exactly why i am posting this.lol
Oct 20, 2011
1112 posts
Mississauga
vanpatrick81 wrote: Mine took a good whole 5 hours to go down from 25 to 23. And after that, it cycles on after 5 minutes of shutting down and runs for about 30 minutes. Note that this was just based on last Sunday or Monday's heat. But once it hits about late evening, it kinda doesn't go on and off as much as its starting to cool down outside.
In my home under the same conditions it would have taken 2 hours with a Lennox 16.5 seer 2.5 ton in a 2400 sq. ft. home (not including basement). That's a big difference between 5 hours and 2 hours. Which goes back to my original thread, there are too many variables.

As for the cost of running the a/c, I don't even think about it as the increased comfort for family and friends, it's well worth it.
Member
Apr 10, 2006
391 posts
MyDream1 wrote: In my home under the same conditions it would have taken 2 hours with a Lennox 16.5 seer 2.5 ton in a 2400 sq. ft. home (not including basement). That's a big difference between 5 hours and 2 hours. Which goes back to my original thread, there are too many variables.

As for the cost of running the a/c, I don't even think about it as the increased comfort for family and friends, it's well worth it.
Yes, you're right. A lot of factors come in to play. My house is only 1850 with an a/c unit provided by the builder. I feel they give you a bit smaller unit or just exact hence it requires a longer time to cool down the house completely. It's the same with my in-laws place. The a/c unit was provided by builder and it also takes a while to cool their house. But my sister's place, which they purchased their own unit, takes a lot shorter to cool down. This considering all homes have windows with blinds that are closed on those hotest days. And what irks me most is my house is a semi and only the back portion of the house gets full brunt of the sun during sunset.
Oct 20, 2011
1112 posts
Mississauga
Just to keep this into perspective, when I initially turn on the a/c it normally takes one hour for any temperature change as it works on lowering the humidity level in the house considerably. After the humidity level is down to about 40% the temperature drops quickly. I based my time considering the a/c was already running and I just wanted to lower the temperature from it's present a/c climate house.
Sr. Member
Mar 19, 2013
696 posts
Variables aside, my A/C will drop the the temp. 1 degree in about an hour. 1100 sq. ft. house. One of the best investments I have made, went many years without, tortured my family, pets & myself.
Oct 9, 2010
2760 posts
Windsor
My home heated from 74°F to 79°F from 10am to 7pm (AC off). From 7pm to midnight, the AC was running the whole time, and it got down to 76 (maybe even 77; I can't remember). So, for my house, it is 1 deg. F every 2 hours ... but I am currently diagnosing my AC system to see if there are issues, as I believe there are.

Edit: My main level is almost always right around 60% humidity as well, and an older home, so not sure if that matters. ~1,200 sq.ft main level (with finished basement)
Member
Apr 30, 2004
271 posts
Must depend on A/C , when outside is 33C -in my small 1800 sq.ft. bungalo from 25c to 24 c - about 2 hrs, but down to 23c- only after sun set, basically never when it is hot outside.
It is 1.5 ton a/c.
Deal Fanatic
Feb 4, 2015
6640 posts
We get alot of sunlight on back of house [faces south west] however front of house always cooler and that is where tstat is located.

Decided to try something recently... fully opened all vents on main floor at back and partially closed vents at front of house. Result is that ac runs for more hours as the tstat not shutting off as quick and back rooms now more in line with front rooms.

So more cost but more comfortable. I believe you want long cycles of ac runs vs many on/off cycles.
Deal Expert
Feb 8, 2014
20023 posts