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  1. #1
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    Replacing existing chiller barrel

    If you were going to replace a 50 ton Carrier 30GB for an apartment complex with smaller air cooled condensers and chiller barrels, pumps controls etc..

    How would you go about sizing the new systems.

    The chilled water coils are 40 year old, do I match the coil load.

    Example: Of one zone

    Existing 9- 2 ton coils and 6- 9000 btuh coils. = 22 1/2 ton

    Or

    How would you size the new replacement barrel.

    Thanks for the help
    Last edited by Roscoe; 09-01-2010 at 06:22 PM.

  2. #2
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    I'll bite (just 'cause that's the mood I'm in).
    50 ton barrel???

  3. #3
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    Are you going to get a new packaged chiller or piece something together?
    UA 100

    It takes three people to do anything around here. Two do the work, one explains to the crowd of people who showed up when they seen smoke and flames.

  4. #4
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    Quote Originally Posted by thegoodlistener View Post
    Are you going to get a new packaged chiller or piece something together?
    This has already been split up into 3 zones with 3....12 ton Standard barrels and 12-1/2 ton Carrier condensers. This was not my concept

    The apt owner who is an Electrical Engineer, basically based the sizing on the square foot of the apartments. I told him he was cutting it short, but it's his dime.

    I know it is under capacity but I can't get it across to him.

    So what I'm asking is, is there anything in black and white that says how to size these properly for replacement.

    There is plenty of info on how to size for new, but nothing that I've seen for splitting up a larger package chiller and replacing it with several smaller systems. Or anyone that has done this before, I appreciate your input.

    Thanks for being a good listener,

    I appreciate any help.

    Roscoe

  5. #5
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    Most people just go back with what was there previously which isn't always the best way to go in certain situations.
    UA 100

    It takes three people to do anything around here. Two do the work, one explains to the crowd of people who showed up when they seen smoke and flames.

  6. #6
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    Quote Originally Posted by thegoodlistener View Post
    Most people just go back with what was there previously which isn't always the best way to go in certain situations.
    I wanted to size the systems to match the existing coils.

    IE: 9- 2 ton coils and 7- 9000 btuh coils = 23.5 tons

    They decided to use a 12 ton, based on apts size. today @ 91* ambient the return water is 71* and supply is 61* a 10 * range but not able to satisfy all the apartments on one of the zones. But hey it works good when it's a 70* ambient.......


    Thanks

    Roscoe

  7. #7
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    If the chillers are to be set up for 45F water, the evap temperature will be around 35F. Those 12.5 ton condensing units are rated at a nominal 45F evap temperature, so the chiller capacity will end up at about 10 tons.

  8. #8
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    According to Standard @ a 10 range and 7* approach, 7*SH and a 27gpm pump we should get 11.2 tons.

    Now since we have 2 ton coils @ 3.5 gpm and some 9000 btuh coils that are all 40 yr old and never were set. And no way to verify the flow rate, I'm out on a limb.

    We talked to the M.E. from Standard, and the M.E. from Carrier Commercial Services (both nice people by the way). They both said you don't have enough capacity. I know that but how do I get this across to the Electrical Engineer/owner. In black and white.

    Oh by the way he (the owner/E.E.) referred to both the M.E.'s as "idiots".

    The other 12 systems 145 tons we put in are all working great.

    Thanks for the input

    Roscoe

  9. #9
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    Give all the tenants in that building his home # to call because they are HOT! Maybe that will convice him he undersized.

  10. #10
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    Sounds like you need to convert everything to KW's for him.
    UA 100

    It takes three people to do anything around here. Two do the work, one explains to the crowd of people who showed up when they seen smoke and flames.

  11. #11
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    Quote Originally Posted by BaldLoonie View Post
    Give all the tenants in that building his home # to call because they are HOT! Maybe that will convice him he undersized.
    Sounds like you need to convert everything to KW's for him.


  12. #12
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    Keep in mind diversity,the original designers did heat load calcs and came up with the sizing but most engineers figure in diversity(not all units will be calling for 100% demand always/system rarely sees design degree days)therefore you connected load may be 100 tons but a 75 ton machine may do job.I would look and see if there are simaler buildings in area and see what they are using as a rough referance?

  13. #13
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    I appreciate that, as I've said we have 145 tons on the roofs of that complex that we installed, other than the one 12 ton system I'm referring to the other13 systems run very well.

    This particular system runs fine and cycles on the set points in the low to mid 80's but looses ground at 90 and basically dies when it hits 95*. The inlet temp is 70* and the outlet is 59* so everything is working good it just can't keep up.

    The problem is obvious to us and the M.E.'s from Carrier and Standard Refrigeration

    I can't get it across to this guy but hey he's a PhD Electrical Engineer, he referred to the M.E.'s as "idiots". He is a good guy, just one stubborn SOB

    If I can show him in black and white where it says >>>>. Replacement chillers are sized on the existing coil load<<<<<<<<<........anybody know where I can find this info

    Thanks
    Roscoe

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