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Si zing Hot Gas By pass

Professor:

I have a 30 ton condsening unit on order, that I need to start piping form the the coil up through the roof. I need to supply a 1-5/8" suction line and a 7/8 liquid line. I have been looking through my copland engineering application mannual and my sporland data books but I can not find the information I need to size my hot gas by pass. I was hoping you could provide me with some information or direct me to a place I could get the correct information I needed. Or to a formula I could use to get this project started?

Thank You

Larry

Comments

  • Techman
    Techman Member Posts: 2,144
    Hot Gas Bypass

    Morning Larry!30 tons, nice! Which brand of equiptment?They should be able to tell you,How much distance between the evap and the cond? do you need a "double suction riser?Enjoy!
  • Larry_25
    Larry_25 Member Posts: 1
    Techman

    Teahman:

    I have about 40 feet between the the evap and the condsening unit. It has two 15 ton circuits on the evaportor and we are putting in hot gas for capasity control. They are York's. It will be a little over 15 foot riser. With the hot gas I can not see the need for a double riser.
  • Empire_2
    Empire_2 Member Posts: 2,343
    Hi Larry

    Q: At 30 ton total loaded capacity are you using 2 suction lines or 1. If 1 line @1 5/8" the velocity in ft/per min is extremely high!!! about 5,200 ft/per min.

    Are you sure it's not 2 5/8"? That would bring your volocity down to 1500 where it should be. If one line per 15 ton circuit then 1 5/8" if fine.

    Hot gas connection on your control should determine your line size.,,.,.I think.

    Mike T.
  • Empire_2
    Empire_2 Member Posts: 2,343
    One more thing....;-)

    I guess I should first ask you what is this application ref., A/C, and refrigerant being used.

    Mike T.
  • Techman
    Techman Member Posts: 2,144
    It's a gas!

    Can the reciever handle the pumpdown capacity?
  • Larry_26
    Larry_26 Member Posts: 2


    > Can the reciever handle the pumpdown capacity?



  • Larry_26
    Larry_26 Member Posts: 2
    Pipe size

    Mike and Teacman:

    I am still waiting on all the information, what I can tell you is that I have two seperate cicuits. I am thinking two fifthteen ton compressors first stage has the hot gas by pass and second comes on as needed depending on the discharge air tempature. It is A/C and is being used in one area for dehumidifation for a pool with a rehaet coil and the other is a AUH for heating and cooling with reheats out in the zoned space. It also has fresh air intake and exhaust air mixing box with feak dives on the blower motors. I can see the need to protect the compressors and keep the load in a stable pressure to prevent short cycling.
    Hope this help out a little. I would wonder too if it was 30 tons on a 1-5/8 line I am just trying to stay ahead of everyone so I don't get buried by the other trades. The engineer is working on the hospital now and it is taking a week or two to get back to me. I was looking on the sporlan sight to find out what I can. I just thought I could bounce it off you guys and I could find the information a little sooner than having to do all the leg work myself. I thought maybe you had come across a faster way. R-22 Mike

    Thanks

    Larry
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