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increasing length of AC cycle

after a warm house hits the thermostat cooling point, the compressor shuts down.

and it turns on and off to keep the set temp level

what range of temp is the best for purposes of lengthening time compressor stays on (ie. turns on at 74 and turns off at 76.  

it would seem a wider range of on/off temp control would tend to decrease stress on compressor (seems 2 or 3 degree range would be comfortable for inhabitants and may be alot better for compressor than a 1 degree range - what is typical range?)



  • Spence
    Spence Member Posts: 316
    AC Cycle

    On the average, it takes 10-12 minutes for a properly sized air conditioner, components in good working order, to remove humidity and bring the space to the set temperature. The time between cycles depends on how quickly the space gains heat and moisture from the atmosphere. However, most thermostat makers build in a nominal 5-minute delay to protect the compressor.
  • elfie
    elfie Member Posts: 264
    thermostat control over cycles

    was interested to know if the AC trade focuses on the issue of controlling the length of cycling time.

    can thermostats be adjusted to change the compressor turn on/off set point range from 1 degree to say 3 degrees (what is normal?)

    would a wider range reduce strain on compressor?
  • Spence
    Spence Member Posts: 316

    How long the thermostat takes to reach the set point is related to several things. For example, the effects of a passing weather system, the thermal integrity of the space, the size and design of the equipment and distribution system, orientation of the structure, location of the thermostat, and others. Contact your local service professional who will be happy to diagnose the reasons your system isn't happy.

    Yes, we are very concerned about cycling. We want your "comfort line" to be as flat as possible, meaning on and off events are less noticeable. This helps to keep even temperatures throughout and efficiency high.
  • elfie
    elfie Member Posts: 264
    not questioning quality or performance of system

    not sure you are understanding my question.

    is thermostat adjustable to control the length of cycling (ie. from 1 degree change to a 3 degree range before compressor shuts down - what is a normal range?); and would there be a benefit to the compressor due to less on/off events. 

    this question has nothing to do with capacity of system - lets assume system is sized correctly.

    thanks, i hope this is clear.
  • Harvey Ramer
    Harvey Ramer Member Posts: 2,225

    Some are and some aren't. Mostly it will be controlled by a minimum off time. The EcoBee does allow more in depth settings.

    Hope that helps.

  • Techman
    Techman Member Posts: 2,144

    As Harvey said ! Is this a 2 stage t'stat? Jumper 1st & 2nd stage  ,that will give you a wider spread.
  • Spence
    Spence Member Posts: 316
    The Light Just Came On

    Right you are; I didn't understand the question. I believe you are referring to the droop adjustment, which allows the compressor to operate to a setting lower than your comfort temperature.

    If you live in an area susceptible to high humidity, three degrees is a good choice, provided you do indeed have the correct size. Dry climates should have the factory settings since you're mainly concerned about the sensible load.