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  1. #14
    Join Date
    Sep 2009
    Location
    S.C.
    Posts
    1,414
    Since we see it daily...

    I think this is pushing the limit on "DIY" rules. Just like you (the OP) everyone who comes here says they are "In the Business". There's a formula to calculate the correct cap. We've discussed it numerous times in the Pro section. If you are in the business after you changed a couple hundred you could make an educated guess on what cap it should have (and be fairly close).

    Apply for a Professional Membership.
    Yes, I know I Shouldn't But I Just Can't Help Myself...

  2. #15
    Join Date
    Aug 2012
    Location
    Palmyra, Missouri, United States
    Posts
    224
    1 ton... HAVE NEVER SEEN a one ton

  3. #16
    Join Date
    Mar 2012
    Location
    New Hampshire
    Posts
    84
    Quote Originally Posted by Home&Marine View Post
    Since we see it daily...

    I think this is pushing the limit on "DIY" rules. Just like you (the OP) everyone who comes here says they are "In the Business". There's a formula to calculate the correct cap. We've discussed it numerous times in the Pro section. If you are in the business after you changed a couple hundred you could make an educated guess on what cap it should have (and be fairly close).

    Apply for a Professional Membership.

  4. #17
    Join Date
    Sep 2002
    Location
    Virginia
    Posts
    3,327
    90 percent of small units are 35 5

  5. #18
    Join Date
    Jul 2012
    Location
    North west Arkansas
    Posts
    86
    Quote Originally Posted by Home&Marine View Post
    Since we see it daily...

    I think this is pushing the limit on "DIY" rules. Just like you (the OP) everyone who comes here says they are "In the Business". There's a formula to calculate the correct cap. We've discussed it numerous times in the Pro section. If you are in the business after you changed a couple hundred you could make an educated guess on what cap it should have (and be fairly close).

    Apply for a Professional Membership.
    Understood Sir, that's what I'll need to do. I haven't been doing this part of the job long, it was just the next step to save my employer money, as well as make more for myself. Haven't changed a lot of caps, with 15 subway restaurants, I eventually will change hundreds, but it's gonna be a while to reach that amount.

    I appreciate all the input thus far, and look forward to picking up quite a bit more knowledge here.

    Thank you gentlemen.

  6. #19
    Join Date
    Oct 2010
    Location
    AZ
    Posts
    647
    Quote Originally Posted by Snapperhead View Post
    90 percent of small units are 35 5
    Or less on the compressor side in my experience. 30uF is also fairly common but I have seen as low as 20uF on smaller units.

  7. #20
    Join Date
    Jul 2012
    Location
    North west Arkansas
    Posts
    86
    Quote Originally Posted by dijit View Post
    Or less on the compressor side in my experience. 30uF is also fairly common but I have seen as low as 20uF on smaller units.
    Just replaced a copeland comp on a walk in cooler, 18000 btu. The copeland had 35mfd, and the new Bristol calls for 25.
    So yeah, think I did go a little high. I believe I'll go back and dig a little more for info on the comp.

  8. #21
    Join Date
    Jan 2009
    Location
    St Peters, Mo
    Posts
    56
    You may get away with the 7.5 on the fan but 50 on a 2 ton compressor is crazy big. I just put a 45 on an old 5 ton!
    Call for Heat means get more firewood

  9. #22
    Join Date
    Feb 2010
    Location
    Calgary, Alberta
    Posts
    1,151
    I just put a 60/7.5 on a 10yr old recip
    Lennox 10acp 2.5 tons.

    That's what the rating plate said!

  10. #23
    Join Date
    Jul 2005
    Posts
    5,576
    Quote Originally Posted by syndicated View Post
    I just put a 60/7.5 on a 10yr old recip
    Lennox 10acp 2.5 tons.

    That's what the rating plate said!
    Yep. Guessing isn't a very good method of sizing capacitors. If you have no other option, then try a few different sizes. Find the size that results in the lowest compressor amp draw (on the common lead). If the voltage across the cap that you've finally selected with this method exceeds the voltage rating of the cap, then go smaller until the voltage drops below the voltage rating of the capacitor. Even if it was accidentally the size called for by the manufacturer, it won't be of much use to the compressor when it opens up due to over-volting.

    I had to use this method a couple of weeks ago. No data on the unit anywhere, and none on the capacitor. I couldn't even determine what brand the unit was. I assume that it's still working fine, since the owner (a long time customer of ours) hasn't called.

  11. #24
    Join Date
    Aug 2004
    Location
    North Richland Hills, Texas
    Posts
    14,915
    It is easy to find what size capacitor is needed, just get the model number of the compressor, and look it up in your Copeland(Emerson), Bristol, or Techumseh book.

    You all do carry all 3 books on your trucks don't you?

    The Bristol and Techumseh books are usually pretty easy to get your hands on, as the reps usually have a few to give out to those who ask at trade shows.
    The little blue book for Copeland[Emerson], can be more difficult to acquire.
    The little green book for Carlyle is a good one to have too.


    Quote Originally Posted by drife678 View Post
    1 ton... HAVE NEVER SEEN a one ton
    AS/Trane used to make 1 ton splits, both straight AC and heat pump, up until a few years ago. Quite a few manufacturers used to.
    If more government is the answer, then it's a really stupid question.

  12. #25
    Join Date
    Nov 2009
    Location
    Kansas City
    Posts
    124
    Ya most of the 2 ton units I have ran into are usually 35/5.carrier two ton units seem to be 30/5. I did run into a 38ycc.-018 1 1/2ton hp the other day and it was 30/5. Like most of you have said. You can usually always read the nameplate on fan motor to get its size

  13. #26
    Join Date
    Jan 2009
    Location
    Etters PA.
    Posts
    517
    Quote Originally Posted by hvacrmedic View Post
    Yep. Guessing isn't a very good method of sizing capacitors. If you have no other option, then try a few different sizes. Find the size that results in the lowest compressor amp draw (on the common lead). If the voltage across the cap that you've finally selected with this method exceeds the voltage rating of the cap, then go smaller until the voltage drops below the voltage rating of the capacitor. Even if it was accidentally the size called for by the manufacturer, it won't be of much use to the compressor when it opens up due to over-volting.

    I had to use this method a couple of weeks ago. No data on the unit anywhere, and none on the capacitor. I couldn't even determine what brand the unit was. I assume that it's still working fine, since the owner (a long time customer of ours) hasn't called.
    A little time saver tip for this method is to stock a multi dual cap on your truck and run threw the procedure stated above .

    Sent from my PC36100 using Tapatalk 2

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