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  1. #40
    [QUOTE]Originally posted by BamaCracker
    [B]Well dang! You only undersized it by 1/2 a ton! That ain't too bad, since the original "expert" put in a 3 1/2 ton unit on a 2.5 ton load, and the house was so uncomfortable we hated it. I finally installed a 3 ton, 2 speed compressor, and converted it to heat pump. It was still oversized in cooling (maintained 67 degrees on a 107Ί day) when on high speed, but the humidity control from running in 1/2 speed was awesome.

    Let me break it down like this. I can see that you guys are having a lot of problems with this so I will simplify it even further.I will use capitols on the important parts of his quote.

    It was STILL OVERSIZED IN COOLING (maintained 67 degrees on a 107 degree day) WHEN ON HIGH SPEED. ( KEY WORD HERE IS WHEN )apparently at 107 out it didn't need to run hi speed very often and probably never would if he didn't try to keep 67.

    The HUMIDITY CONTROL from RUNNING 1\2 SPEED WAS AWESOME.

    If it truly is half speed or half capacity it is at 18k, now lets do the math folks.

    36k 2 Speed =107 OA 67space temp = unit cycles to low speed

    24k =95 OA single stage 72 space temp = unit satisfies and cycles off.

    Beleivable ? the only realistic is yes Fat Eddy I can beleive that, anything other than that would be pure stupidity.

    And here is the topper the guy does a load calc and it comes out to 31k so whats he do he goes and puts in a 36k

    Thats exactly how the whole thing got started to begin with.





    [Edited by fat eddy on 02-25-2005 at 11:52 PM]

  2. #41
    Join Date
    May 2001
    Location
    Kansas City
    Posts
    2,729
    Dang, now Fat Eddy's running circles around BamaCracker. I like FE, of course I miss Floor Furnace.
    Never argue with an Idiot, they drag you down to their level and beat you at their own game.

  3. #42
    Whats your game? would you like to lose at that also ?

  4. #43
    Join Date
    Nov 2004
    Location
    CA
    Posts
    238
    Congrats Fat Edi. For some reasons we tink likewise, absolutely.

    It happened to me to replace an Evap. coil which was 1/2 ton larger than the condensing unit. It was Sat. and I only had this size in my truck. Promised to the lady to come back and put the matching size. Of course when I charge up the system I had to put a bit more R22. To my suprise - when I went back on Monday with the correct size coil - the lady said she was very happy the way it is. What she did not understand was the that dehumidification was way better with the larger evap. coil.

  5. #44
    Thats because there is more surface area a point that many here can not grasp although it is in every decent HVAC book you can find.

  6. #45
    Join Date
    Nov 2004
    Location
    CA
    Posts
    238
    Right on, man !

    Increased surface will increase the efficiency. Same idea on the increased Condensing coil surface to gain more subcooling, hence more efficient at the metering device.

  7. #46
    Yes, bigger condenser surface, closer approach, little extra subcooling, a little less flash and pow its more efficeint.

  8. #47
    Join Date
    Jan 2005
    Location
    Seattle
    Posts
    191

    Cool load cals or not

    ColdBud.
    To answer your question.Get the
    load calc done for YOUR home.
    This thread got a little side tracted
    from the question you asked.Some peaple
    guess right some of the time.but thier
    not right all the time.It is your
    money and your home.Spend the time
    to find a honest and intelligent
    hvac guy that will look at your
    whole system.And knows that he
    is spending your money and trust.
    Even if he can eyeball it and tell
    you nuts on.It should be no problem
    to show you the numbers to help
    put your money at ease.

    Now as far as FatEddy goes.
    He feels rather highly of himself.
    And seems to be self righteous
    in a angry sort of way.If you were
    to hire him. Because he is so
    intelligent that he can pick
    out the size of the equipment
    you need with just a little information.
    Or a good look at your house.
    Bear in mind who you would really
    be hiring.I will refer you to
    this thread titled "honest answerers
    only please.It is currently available
    for your viewing in the residential
    hvac forom.
    http://HVAC-Talk.com/vbb/showthread.php?threadid=70748.

    After you read this. I think it will
    substantiate why in this forom
    it is said. It is the quality of
    the install and the installer that
    counts.
    41Gasman

    P.S SPLAT!!!

  9. #48
    Join Date
    Jan 2001
    Location
    Pacific Coast of Canada
    Posts
    4,008
    Originally posted by rsmith46
    Dang, now Fat Eddy's running circles around BamaCracker. I like FE, of course I miss Floor Furnace.
    Never argue with an Idiot, they drag you down to their level and beat you at their own game.
    Why is it every few months someone shows up knowing everything? Then they want to argue with Bama?

    I liked the floor furnace reference, Mr Smith.

  10. #49
    Join Date
    Mar 2004
    Location
    Gone
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    5,340
    Originally posted by swampfox
    So lets get this straight, even after you find the load is 31k, you still think 24k will do the job at design conditions, and the oversized evap and 450 cfm/ton is for extra latent capacity, am I reading all this right?

    Oversized evaporator coils DO NOT give you more latent. They give you the opposite. They give you more sensible and take away your latent (humidity) control. Increasing air flow also DECREASES your latent (HUMIDITY) control.

    His 24K design wouldn't work. I will explain in a second.

  11. #50
    Join Date
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    Originally posted by fat eddy
    What part was I wrong on, do tell me please. he did a load calc it came out to 31k which is less than 2.5 ton but close, load calcs in general tend to oversize by 20% that puts me right on the money and I assure that the size I chose would handle his home on any design day.

    He also stated that he chose to go with a two speed compressor and that he got good dehum when it was running at low speed ( which is probably all the time) low speed is typically 60%, 60% of 36k is about 21k.

    You are always better off undersizing than oversizing if you undersize you will get better pressures in your system.

    The 36k unit kept his home at 67 when it was 107 out, would that make you think that it is still grossly oversized?

    He actually ended up with exactly what I recommended a two ton unit with an oversized coil. And thats all he needed for design conditions. Case Closed,
    What part was I wrong on, do tell me please. he did a load calc it came out to 31k which is less than 2.5 ton but close,
    …………31K is more than 2 ½ tons, which is 30K actually, and most only put out 29K, so you are wrong here since you asked to have it brought to your attention.
    load calcs in general tend to oversize by 20% that puts me right on the money and I assure that the size I chose would handle his home on any design day.
    ………….there is slop built in for a reason, and you do not even understand why. By you trying to take the slop out and make your sizing work in this application is unprofessional and not the way it should be engineered.
    He also stated that he chose to go with a two speed compressor and that he got good dehum when it was running at low speed ( which is probably all the time) low speed is typically 60%, 60% of 36k is about 21k.
    …………..here you are again trying to show where low speed will fit your high speed load. Not comparing apples to apples here are we?

    You are always better off undersizing than oversizing if you undersize you will get better pressures in your system.
    ………….Since when do we size a system by the pressures, and last I looked, it is superheat or subcooling which matters, but being a fitter as you proclaim to be, well………

    The 36k unit kept his home at 67 when it was 107 out, would that make you think that it is still grossly oversized?
    …………..no, it shows he has excellent insulation.

    He actually ended up with exactly what I recommended a two ton unit with an oversized coil. And thats all he needed for design conditions. Case Closed,
    …………..wrong. He ended up with a system perfectly matched. 31k is over 2 ½ tons, so going up to 3 tons is correct.


  12. #51
    Join Date
    Mar 2004
    Location
    Gone
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    5,340
    [QUOTE]Originally posted by fat eddy
    [B]
    Originally posted by BamaCracker
    Well dang! You only undersized it by 1/2 a ton! That ain't too bad, since the original "expert" put in a 3 1/2 ton unit on a 2.5 ton load, and the house was so uncomfortable we hated it. I finally installed a 3 ton, 2 speed compressor, and converted it to heat pump. It was still oversized in cooling (maintained 67 degrees on a 107Ί day) when on high speed, but the humidity control from running in 1/2 speed was awesome.

    Let me break it down like this. I can see that you guys are having a lot of problems with this so I will simplify it even further.I will use capitols on the important parts of his quote.

    It was STILL OVERSIZED IN COOLING (maintained 67 degrees on a 107 degree day) WHEN ON HIGH SPEED. ( KEY WORD HERE IS WHEN )apparently at 107 out it didn't need to run hi speed very often and probably never would if he didn't try to keep 67.

    The HUMIDITY CONTROL from RUNNING 1\2 SPEED WAS AWESOME.

    If it truly is half speed or half capacity it is at 18k, now lets do the math folks.

    36k 2 Speed =107 OA 67space temp = unit cycles to low speed

    24k =95 OA single stage 72 space temp = unit satisfies and cycles off.

    Beleivable ? the only realistic is yes Fat Eddy I can beleive that, anything other than that would be pure stupidity.

    And here is the topper the guy does a load calc and it comes out to 31k so whats he do he goes and puts in a 36k

    Thats exactly how the whole thing got started to begin with.





    [Edited by fat eddy on 02-25-2005 at 11:52 PM]
    You are trying to justify putting in your system here which would only keep up to the correct sized system when it is running in low speed.

    What are you going to do during the 3 months he needs full load in HOT Oklahoma when he needs it?

    This is better than some of the jokes on David Letterman.

  13. #52
    Join Date
    Mar 2004
    Location
    Gone
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    5,340
    Originally posted by bananaboy
    Congrats Fat Edi. For some reasons we tink likewise, absolutely.

    It happened to me to replace an Evap. coil which was 1/2 ton larger than the condensing unit. It was Sat. and I only had this size in my truck. Promised to the lady to come back and put the matching size. Of course when I charge up the system I had to put a bit more R22. To my suprise - when I went back on Monday with the correct size coil - the lady said she was very happy the way it is. What she did not understand was the that dehumidification was way better with the larger evap. coil.
    So you replaced a bad clogged up coil, and the customer felt better because anything other than the bad coil would have made anyone feel better, and you think she knows the difference between so so humidity control and good humidity control with the correct coil.

    What you do not understand is you do not get better humidity control with a bigger coil. You get better efficiency, but not better humidity control.

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