Page 1 of 3 123 LastLast
Results 1 to 10 of 26

Thread: 5 Ton AC load

  1. #1
    Join Date
    Aug 2008
    Posts
    18

    5 Ton AC load

    Hi, I am curious to know what is the approximate Power consumption of a 5 Ton AC, doesnt matter if it is single or 3 phase.

    I have seen wide ranges of power consumption from different electricians.

    Is is accurate to say the power from a 5 Ton AC is about 7 kW to 9 kW, with 9 kW being the starting power and it levels off to abut 6 or 7 kW?????


    Is this roughly accurate???

  2. #2
    Join Date
    Feb 2003
    Location
    Plano, TX
    Posts
    3,736
    There is really no correct answer to your question.

    The question of trying to convert a one ton A/C unit into VA or kw/hr consumed is very dependant on the make and model of the air-conditioner, as well as its EER (energy Efficiency Rate). These range from 6-14 EER. Standard average one ton A/C unit consumes 1.335 KW/hr. But you can only use that as an estimating tool.

  3. #3
    Join Date
    Aug 2007
    Posts
    2,754
    I am curious as to why you are curious about the average power consumption (care to explain ?) How does that help in engineering any specific job ? (I guess what I am trying to say is that it is easy to get into trouble using a number for a project which may or may not represent reality, when it is just as easy to get a spec sheet and specify an exact piece of equipment that will work and use that value, knowing that that equipment actually exists and can be used in the installation)

  4. #4
    Join Date
    Dec 2008
    Posts
    1
    I could see where have a general number could be beneficial from a Utility's perspective in sizing the service conductor and/or XFMR. Very often homeowners only know the tonnage of their units and do not have a spec sheet readily availble for the power company. Thus the company would have to use judgement in sizing for the full load of the unit as well as any possible flicker from starting. I use 1.5 KVA per ton of AC for full load calculations and 1.5hp per ton for starting calculations(assuming code G). These are of course very very general and I encourage you to do more research if possible.

  5. #5
    Join Date
    Feb 2005
    Location
    Charlotte, NC
    Posts
    6,292
    Quote Originally Posted by cubdh View Post
    Hi, I am curious to know what is the approximate Power consumption of a 5 Ton AC
    About 4 tons of electricity (thanks I will be here all week, tip your servers)

  6. #6
    Join Date
    Jul 2007
    Location
    Iowegia
    Posts
    16,796
    I think trying to convert AC tonnage to power consumption is like converting automotive engine HP to mileage.

  7. #7
    Join Date
    Nov 2007
    Posts
    306
    Quote Originally Posted by cubdh View Post
    Hi, I am curious to know what is the approximate Power consumption of a 5 Ton AC, doesnt matter if it is single or 3 phase.

    I have seen wide ranges of power consumption from different electricians.

    Is is accurate to say the power from a 5 Ton AC is about 7 kW to 9 kW, with 9 kW being the starting power and it levels off to abut 6 or 7 kW?????


    Is this roughly accurate???
    Your guesstimate is wrong; as it should be!

    Here it is:
    1 ton of cooling = 12,000 BTUs of heat = 3.513725 kilowatt-hours
    5 tons of cooling = 5 X 3.513725 = 60,000 BTUs = 17.57 kWH

  8. #8
    Join Date
    Jan 2004
    Location
    Right here.
    Posts
    12,326
    One horsepower per ton is still a pretty decent rule of thumb for condensing units. That goes up if it's an entire RTU.

  9. #9
    Join Date
    Sep 2004
    Posts
    1,410
    Quote Originally Posted by topgone View Post
    Your guesstimate is wrong; as it should be!

    Here it is:
    1 ton of cooling = 12,000 BTUs of heat = 3.513725 kilowatt-hours
    5 tons of cooling = 5 X 3.513725 = 60,000 BTUs = 17.57 kWH
    You're assuming there is a 1:1 conversion between cooling tons and applied energy. If an AC worked like a resistance heater, that would be a good assumption. But they don't work that way.

    The EER is a factor that tells you how to divide the BTU usage to get the actual consumed power (but look out, the 3.412 BTU conversion factor is in there too). EERs vary by temperature and the design of the equipment (newer units being more efficient than old ones, mostly because they have larger coils). The KW value above needs to be divided by a factor between 2 and 4. Power use is roughly TONS * 12000 / EER. Note that this method is not a good way to derive amps or MCA -- need the nameplate or datasheet for that.
    Mark
    Kent, WA

  10. #10
    Join Date
    Dec 2005
    Location
    The Sooner Nation
    Posts
    2,437
    Marc and Mark are right. A rule of thumb is the best that you are going to get, without some name plate info. 1hp for 1ton split A/C single phase system, less for a 3 phase.
    My son is one of the Few, the Proud, the Infidel.
    Sgt. Mickey, 0311 USMC

Posting Permissions

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