can some kind person please fully explain CPH to me?

Old 04-26-11, 06:03 PM
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can some kind person please fully explain CPH to me?

I have a honeywell programmable and for some reason I cannot grasp the concept of CPH no matter how much reading I have done.

in the winter I an use the thermostat to allow colder daytime temps and warmer night temps but in the summer, that theory does not fly. if I let my house get to 85 during the day, it will run ALL night trying to get it back to 75 as it is set.

is this a lousy/underperforming unit or a cph problem?
Old 04-27-11, 05:22 AM
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I'm not an ac guy, but the recovery time for ac is usually longer than heat. The reason is, too big of an ac unit will leave a home cold and humid. A smaller unit will run longer and remove more humidity, but might struggle to recover from your settings.

As for cycles per hour, one of the ac guys will need to comment, a change may help.

Old 04-27-11, 06:10 AM
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Not sure about the concept of CPH, but if your system takes all night to get from 85F to 75F, you definitely have a problem, either your A/C system is too small, or have some problem, or not enough insulation in your house. (What's your temp split ??)

Last edited by clocert; 04-27-11 at 07:17 AM.
Old 04-27-11, 03:17 PM
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cph is cycles per hour and has nothing to do with temperature set back. CPH for AC should be set to 3 in t-stat setup....... but as Clocert said, most likely a problem with a/c not stat.
Old 04-27-11, 03:53 PM
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I need to throw in here...

If you have a house like me (lots of sun and masonry/stucco construction...stores the heat and releases it slowly) really don't want a setback for A/C. Even back in VA...when I had a cheapo thermostat...if it went past 10 AM or so..the A/C would run all afternoon to catch up.

Heat setbacks work ok, because they warm the air...a/c not so much because all the walls and contents get hot and keep radiating even after the air is cool. Just my experience....
Old 04-27-11, 06:41 PM
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your really better off maintaning a temp throughout the day. say setback at night, but once morning rolls around then you want to try to get down to a desired temp and maintain. the house should easily be able to cool down to 75 as long as its not scorching outside. NJ design for system sizing is 75 indoors with 50% R.H when its 90 degrees outside. make sure your system has a proper charge (hire someone if you are not EPA cert)
Old 04-27-11, 07:19 PM
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If it is above design temp the unit should run all day and into the evening. This is normal. If your unit is cycling during higher than design temps it is over sized.

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