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  1. #14
    Join Date
    Jul 2006
    Location
    Philly
    Posts
    63
    How much pressure are you losing?

  2. #15
    Join Date
    Aug 2006
    Location
    Mixing oil and fire with a big spoon.
    Posts
    4,271
    where are you measuring your psig requirement and when? the building i was talking about before, was measuring at the inlet of the chilled water pump in the basement. while the pump was running, the suction to the pump would drop (naturally), the glycol pump would turn on and fill the system to "12 psig". when the pump would turn off, because it was in the basement, the static pressure would cause the pressure relief to open, dropping the system pressure. the pump would turn on again...well you get the idea. we could not find any leaks. we filled the system up while the pump was off and isolated the glycol. we have yet to lose a drop. now we are waiting to see if they want to put the measurement point in the penthouse where it really counts.
    my 1st time jumping out of a plane...http://youtu.be/Kv38G0MHsGo

  3. #16
    If you are maintaining daily logs on your chillers and pumps, you will be able to see what the common operating pressures are for your chilled water loop.
    I don't think 65 psig is necessarily high. If your daily logs reveal your operating pressures to be at 65 psig then your HVAC tech is probably wanting to simply leak test your loop at what he expects it to be operating at.
    Also, if you test your chilled loop as part of your water treatment program any history of a steady decline in chemical (before adding the glycol) could be an indication of a leak.

  4. #17

    Glycol chilled water loop question

    If you are maintaining daily logs on your chillers and pumps, you will be able to see what the common operating pressures are for your chilled water loop.
    I don't think 65 psig is necessarily high. If your daily logs reveal your operating pressures to be at 65 psig then your HVAC tech is probably wanting to simply leak test your loop at what he expects it to be operating at.
    Also, if you test your chilled loop as part of your water treatment program any history of a steady decline in chemical (before adding the glycol) could be an indication of a leak.

  5. #18
    Join Date
    Mar 2004
    Location
    midwest
    Posts
    954
    I have had older systems coverted to glycol and sometimes the glycol solution will leak at older joints, valves, etc. Make sure your not loosing it out the fittings or seals. 1 psi will raise water 2.1ft. give or take
    An astronaut stuck in space was asked by a reporter, "How do you feel?"
    "How would you feel," the astronaut replied, "if you were stuck here, on top of 20,000 parts each one supplied by the lowest bidder?"

    "do it right or do it twice"

  6. #19
    Join Date
    Nov 2002
    Location
    NJ - WORK IN NYC AREA
    Posts
    1,434

    Smile

    WCC,
    Keep this in mind. If you have found no leaks, no system is going to stay at a constant pressure. No pumps running and the system sitting, there is still expansion and contraction.
    All areas the pipe runs through will have some effect on its pressure. However you should not be dropping excessivly. Any draft on the coils that have the fluid in them will effect the system pressure. Any pipe chases or rooms that are warm or cool will effect the temp of your solution, pressure will change. Even when there insullated! This hoping you have done a good venting job?
    "My hands are for sale"

  7. #20
    Join Date
    Jan 2007
    Posts
    8
    Thanks for all of the suggestions. As I said, this is the first time we are going to run glycol in this system. For whatever reason, the system seems to hold 30 PSI rock solid. Since we don't seem to have any leaks, we decided to use that as a starting point and work our way up from there if necessary.The bldg is 55 years old, AHU equipment & chillers are new, piping is original. We're going through a learning curve on how this will work in our c/w loop. Thanks again, Gene

  8. #21
    Join Date
    Feb 2006
    Posts
    224
    WCC, 27.625 inches(2.3ft.) of water column will give you 1 psi pressure at the bottom of that column of" water". water has a specific gravity of 1. prop. gyl of 30% is heavier than water and would give you a greater psi.
    i think(but not 100% sure) that it would give you equivlant to its specific gravity which i would guess to be about 1.15 SP.GR. ( you can verify SP.GR. from charts).
    if it is 60 ft hieght from bottm to top of piping ,Equation is 60/ 2.3=26x 1.15=30psi. plus 6 psi for safety=36psi

    if it is chilled water run that chiller to temp before opening to expansion tank.if it is bladder type exp. tank set that bladder at 36 psi at design temp ie.42F.
    no need to be at 65, and what was old water system at?doubling the pressure is asking for trouble on old piping.

  9. #22
    This is the Ask Our Pro's forum. In order to post a response here, you must have verified qualifications and have been approved by the AOP Committee. You may ask a question by starting a new thread.

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    Last edited by jpsmith1cm; 03-03-2013 at 11:24 AM. Reason: non AOP member

  10. #23
    Join Date
    Sep 2008
    Location
    Western PA
    Posts
    25,440
    mayank

    This is the Ask Our Pro's forum. In order to post a response here, you must have verified qualifications and have been approved by the AOP Committee. You may ask a question by starting a new thread.

    You can find the rules for posting and qualifications here.

    Additional infractions may result in loss of posting privileges.

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