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Thread: Glycol or not??

  1. #1
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    Jun 2006
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    Glycol or not??

    I had some biological growth in a chilled water loop and have determined why it occurred and how to eliminate it. Now, I have a question. This loop is not pressurized other than the pump pressure and the glycol mix is circulated through a large tank with a loose fitting lid. There is no seal and that is the way the chiller was built. Do I need glycol in this thing? The only way it could freeze up is if the compressor contacts welded closed. It has an operating control, flow switch and manual reset freeze stat. None of this loop is exposed to OSA. I'd like to run water in this thing just like I do with my chillers. Another thing is we have city water back-up and when or if we switch, we loose about $1000 worth of glycol. Opions please. Thanks, Ken

  2. #2
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    Was it spec'ed to have glycol in it? If not, take it out if you're comfortable doing it. If it was, then asking someone that you don't know to advise you to do something that may be a detriment to your customers system ain't really the correct thing to do.

  3. #3
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    So I'm supposed to know everyone here before I ask a question? I was simply asking for an opinion on this system and can do without the sarcasm.

  4. #4
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    Quote Originally Posted by joken View Post
    So I'm supposed to know everyone here before I ask a question? I was simply asking for an opinion on this system and can do without the sarcasm.
    Nope, you can't know everyone here before asking a question, and there was no sarcasm intended. Just a way of saying that sometimes we all ask questions that can't reasonably be answered. I, for one, have been placed in the position many times over of giving an opinion, someone takes that opinion and does what they interpreted me to have said (not what I did say), something was messed up, and the responsible party said "All I did was what he told me to do". The question that you asked was not of the typical troubleshooting/testing type, but more one that can have far-reaching and very expensive ramifications if taken lightly. The $64,000.00 question here is not can you take it out (it's pretty obvious that you can), but what is the design specification of the system, or why was the glycol added in the first place, and is removing it going to place the system in jeopardy of damage? You're the only one that has access to the answer to that question.

    So here's my opinion: Was it spec'ed to have glycol in it? You can take it out if you're comfortable doing so.

  5. #5
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    FWIW, I saw no sarcasm. Just like I saw no design chill water temperature, no actual chill water temperature, no system application, in fact, nothing to help others help to advise you, joken. I see from your profile you manage HVAC for a hospital. Is it possible this is a dedicated system for the OR? They typically run at a lower temperature than comfort cooling and sometimes the design is low enough to warrant the designer to spec glycol as a "fudge factor" for safety's sake in case of things such as sensor error or control accuracy. Regardless, if you change something from design now, how can you be sure someone later won't change it back to design? I am not advising either way, just reminding you there are many possibilities and scenarios to be aware of prior to making such a decision. Not the least of which is "who would be financially responsible for any unintended consequences?".

  6. #6
    Nuclrchiller is correct you must know what was designed before you make changes. Application will change any system. Glycol will reduce system efficiency by ratio used. The lower the freeze protection the less efficient thermal transfer. If the system will run well above freezing and away form outside air temps. Treated water will run just fine. You must keep up on treatment and testing especially with a open loop to prevent system failures. Meany systems use glycol as inhibitor to prevent growth. I would keep the glycol just as a safety net to prevent problems. I ran into a system that had treated water in a closed loop for comfort cooling. On one unit the out side air damper failed and froze the coil flooding the kitchen. It was not a large coil but very hard to replace and made a large mess, so beware.

  7. #7
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    I think a better approach would be to take a look at the city water changeover. Is there a way to re-pipe/add solenoids etc. that may prevent the loss of all your glycol. You may lose the glycol in the loop but not in your tank.

  8. #8
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    Jun 2006
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    Thanks, we do just loose the loops. FWIW it's a 42 degree loop that goes to a couple of plate heat exchangers that cool Clinac cancer treatment machines (Radiation).

  9. #9
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    Feb 2011
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    Atlantic City, New Jersey
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    We often service medical facilities as a specialty. Most manufacturers or thier reps will have the reason they have glycol in the system and at what percentage it should run. If you cannot find the specs I would ask one of them and if you ned help locating who that is let me know and i will get you a phone number for the FSE in your area.


  10. #10
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    I work on Filtrene chillers for linear accelerators, and they were having the same issue. They engineered a fix utilizing a small heat exchanger whereby the city water actually cooled the glycol loop when energized. Just a thought. Good luck.

  11. #11
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    Monkeyman, In this case where everything is indoors do you see any reason to run glycol? It's no different than any typical chilled water system. IMO the only thing that would cause a freeze up is if the mag contacts welded closed. The Varian Tech wants cold water and doesn't care whether it's glycol or not. I have a Filtrine too and it's a PITA to work on. Thanks, Ken

  12. #12
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    I personally am not familiar with your equipment but, having said that, if the entire loop is restricted to a conditioned space, I see no fear of the loop "icing up". There might however be another reason for the glycol, to prevent/slow corrosion in your heat exchanger. I would do some further investigation before eliminating the glycol. Good luck.

  13. #13
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    Jun 2006
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    Corrosion inhibitor and normal water analysis. Thanks a lot, Ken

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