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Thread: long line set

  1. #1
    eric_air is offline Regular Member - bad email address, live.com Contact Admin
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    long line set

    5 ton split system heat pump . air handler is 40 feet vertically down and 30 horizontally over from condensing unit. would there be an oil return issue.

  2. #2
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    install stuff

    I normally fix things after they are in but for install jobs a trap for every 10 foot of rise is the norm and with the length of the run going up one size on the lineset will help.

  3. #3
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    It should say in the instillation instructions.

  4. #4
    eric_air is offline Regular Member - bad email address, live.com Contact Admin
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    if i installed it i would have read it too.

  5. #5
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    The instillation instructions are no where to be found? What's the unit model numbers for indoor and outdoor and manufacturer?

  6. #6
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    find the instructions...like you said...you did not put it in, so you are not liable. sounds like a long way to me. remember, scrolls do not have nearly as much oil as a recip, so you have to be careful with traps. you could run out of oil filling even short radius traps.
    my 1st time jumping out of a plane...http://youtu.be/Kv38G0MHsGo

  7. #7
    eric_air is offline Regular Member - bad email address, live.com Contact Admin
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    Quote Originally Posted by jayguy View Post
    find the instructions...like you said...you did not put it in, so you are not liable. sounds like a long way to me. remember, scrolls do not have nearly as much oil as a recip, so you have to be careful with traps. you could run out of oil filling even short radius traps.
    thanks

  8. #8
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    You can also call the manufacturer and ask what they recommend and ask them where you can download the instructions.

  9. #9
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    Scrolls seem to handle this particular scenario pretty well in my experience. I'd be more concerned about pressure drop and liquid flashing off before it makes it's way to the metering device.

    51fitter: When you say increasing the size of the lineset, you do mean suction only, right? With a rise like that, I wouldn't think upsizing the liquid line to 1/2" would be practical.
    "There is no greater inequality than the equal treatment of unequals."

    -Thomas Jefferson

  10. #10
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    Ever heard of a line sizing diagram...?

    if not I can send you one that i've been using fro 20 years.

    JS

  11. #11
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    lines

    You want to upsize both lines liquid and suction. You don't want to run a lil 3/8 line 100 feet and expect good return in a big suction line. Also the manufact. might recomend adding oil to the system because of the location of the evap.

  12. #12
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    Quote Originally Posted by 51fitter View Post
    You want to upsize both lines liquid and suction. You don't want to run a lil 3/8 line 100 feet and expect good return in a big suction line. Also the manufact. might recomend adding oil to the system because of the location of the evap.
    I agree, the pressure drop thru that 3/8 line could eat up all of your sub-cooling and rob your efficiency.

  13. #13
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    i am not so sure about incresing pipe size, i am not sure what freon you are using but assuming R22 using 3/8 liq line and 1 1/8 suction line. the problem you will have is oil return, suction risers should be sized for between 1000 and 4000 FPM velocity to lift the oil out of the trap and up 20 ft to the next trap. if you go to 1 3/8 the velocity drops off to 1100 FPM. too close to the minimum for me, 1 1/8 gives you 1750 fpm and 7/8 gives you 3000 fpm.
    if you go 30 ft horizontal at 1 1/8 you get .75 psi press drop or less.
    if you go 40 ft vertical with 7/8 you get 3.2 drop, if 1 1/8 you get 1 psi drop.
    you should be trying to keep it under 3 psi total drop on the suction line.
    keep the traps as short as possible short radius 90 and two street 45. you only need it to trap small amount to lift it, you dont need a bucket full in each trap and nothing where you need it.

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