cycle times

[tlj]

How do you determine if AC cycle times are appropriate? or what would be considered short cycling? I'm assuming there are number of factors that determine this, but I'm looking for what professionals consider as examples of good cycling times.

Thanks.

[Jultzya]

What cycle times do you have?

What's the indoor/outdoor temp & humidity level at time of test?

[docholiday]

Lets just say if it comes on and off (one cycle) 5 times an hour its about as many as you should ever see, and normally less than that. More and you have a slight problem. You may see fewer but that isnt a problem unless you see big temperature swings.

[tlj]

jultzya,

outside temp is about 90 with 37% humidity... I have thermostat set at 75 and the indoor humidity is 43%.

My cycle times during the test have been approx. 6-15 minutes off and 8 - 15 minutes on... The outdoor temp rose approximately 6 degrees during the three hours I was monitoring the cycles.

Thanks

[Jultzya]

You have more humidity in your home than outside???

[tlj]

That's what the gauges tell me... I'm not sure why...

[beenthere]

Whats your average high temp for your summers?

If your design temp is 100 or more, your cycle times aren't bad.

Set for 75°, I can see your rh inside being higher then your rh outside, your blower might be set for 450, or more cfm per ton.

[amd]

It’s called relative humidity for a reason - 90F @ 37% has a higher dewpoint than 75F @ 43%.

[Jultzya]

My Pentium froze up for a minute!

Thanks for resetting the computer.

[docholiday]

Amd is right, its relative. And you have less indoors, not more.

Another way to look at it is the grains of moisture. In your case at that moment in time, the outdoor air held 78.29 grains of moisture while your inside air was at 55.69 grains of moisture.

Back to the original post. If you have a 15 minute on and 15 minutes off, thats a 30 minute cycle. 2 per hour. If on the other hand you had 6 off and 8 on, thats a 14 minute cycle, a little short but acceptable. Or 4 per hour.

If your load was higher, you might end up with longer on and shorter off. I suspect you were seeing the shorter off cycles with the longer on cycles as it warmed up.

[Special Ed]

Originally posted by jultzya
You have more humidity in your home than outside???

Uh.... Yeah!

Especially if he lives in a desert climate, which it sounds like he does.

[cem-bsee]

one more time -- rotating equipment is rated for so many starts per hour --

nominally the a/c compressor is rated at FOUR = 4.

as usual, check with the specific manufacturer.