Results 1 to 12 of 12

Thread: cycle times

  1. #1
    Join Date
    Apr 2005
    Posts
    4
    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.

  2. #2
    What cycle times do you have?

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

  3. #3
    Join Date
    Apr 2004
    Posts
    7,680
    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.

  4. #4
    Join Date
    Apr 2005
    Posts
    4
    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

  5. #5
    You have more humidity in your home than outside???

  6. #6
    Join Date
    Apr 2005
    Posts
    4
    That's what the gauges tell me... I'm not sure why...

  7. #7
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    68,074
    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.
    Contractor locator map

    How-to-apply-for-Professional

    How many times must one fix something before it is fixed?

  8. #8
    Join Date
    Sep 2002
    Location
    I don't know
    Posts
    2,903
    It’s called relative humidity for a reason - 90F @ 37% has a higher dewpoint than 75F @ 43%.

  9. #9

    amd

    My Pentium froze up for a minute!

    Thanks for resetting the computer.

  10. #10
    Join Date
    Apr 2004
    Posts
    7,680
    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.

  11. #11
    Join Date
    Jun 2003
    Location
    Jacksonville, FL.
    Posts
    4,313
    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.
    WHY?

  12. #12
    Join Date
    Feb 2003
    Location
    Huntsville,AL
    Posts
    4,125
    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.
    harvest rainwater,make SHADE,R75/50/30= roof/wall/floor, use HVAC mastic,caulk all wall seams!

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  
Comfortech Show Promo Image

Related Forums

Plumbing Talks | Contractor Magazine
Forums | Electrical Construction & Maintenance (EC&M) Magazine
Comfortech365 Virtual Event