# Thread: Determining cooling hours

1. Regular Guest
Join Date
Aug 2008
Posts
107
Post Likes

## Determining cooling hours

I was looking at the hvacopcost website and it shows 2800 cooling hours. What parameters are they using to calculate cooling hours? Is this at a 75 degree temperature set point? Is there a site where I can find cooling hours for my area using different set points?

2. This may be the closest to what you are looking for. - Darrell

3. Regular Guest
Join Date
Jun 2009
Location
Spicewood, Tx
Posts
41
Post Likes
If you don't mind a few hrs work, you can make any data set you want from the nearest weather site. I did this yesterday for Central Texas, pulled hourly data from May, 2008 thru Sept., 2008. Then for more detailed info, I split the data into 5 degree intervals. There were a few missed observations, but out of 3544 total hours, 425 hrs < 71F, 736 hrs between 71 & 75F, 766 hrs between 76 & 80F, 530 hrs between 81 & 85F, 522 hrs between 86 & 90F, 431 hrs between 91 & 95F, 132 hrs between 96 & 100F and 2 hrs > 100F. By combining this info with both load calculations and system peformance at different ambient air temps, I may get a better understanding of operating cost and operating hours.

4. Regular Guest
Join Date
Jun 2009
Location
Spicewood, Tx
Posts
41
Post Likes
Originally Posted by udarrell
This may be the closest to what you are looking for. - Darrell

That chart is pretty accurate, at least in my case. It shows between 1250 hrs and 1500 hrs of system operation. My data shows May thru Sept. a total of 3544 hrs with 2383 hrs above 75F. I calculate a 2.5T, 15 SEER system would run for 1397 hrs and use 3432 kW. A 3.0T, 16 SEER system running on 1st stage only would run for 1594 hrs but use only 2893 kW.

5. If it wasn't for the fact that the sun is a big part of the cooling load, I would almost say that there would be merit in the 'cooling hours' based on temperature alone

#### Posting Permissions

• You may not post new threads
• You may not post replies
• You may not post attachments
• You may not edit your posts
•

## Related Forums

The place where Electrical professionals meet.