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Thread: glycol to water ratio in chiller reservoir

  1. #1
    Join Date
    Jun 2006
    Tampa, Florida

    glycol to water ratio in chiller reservoir

    I have been working on a start up brewpub that has been a scrape by situation from the start but is slowly getting better bit by bit. The main problem that I am having right now is I need a chart that tells me the appropriate specific gravity of glycol concentrations in the chiller reservoir(the big chiller that chills my fermenters) and what temperatures they are good for. My chiller doesn't have the typical coils in the reservoir set up instead it has a coil that is inline out of the reservoir that is chilled by the compressor coil. It is wrapped in what appears to be just styrofoam and felt after that. I have had quite a few freeze ups and my boss is basically saying that I will destroy the chiller if I keep freezing it up and I keep telling him our glycol concentrations are too low and that is why it is freezing up(2.8 degrees plato in the reservoir). I know in the past it seems like the target specific was 1.060 to 1.080 but can't convince him to buy glycol and I am on the verge of being locked out of my chiller room because he says it is my fault. The chiller has never chilled my fermenters down any colder than 40 F and most recently does no better than 48 F. Also, knockout is problematic because my chiller runs a secondary process on my heat exchanger which isn't getting me down to the intial fermentation starting point that I need(55-58F...using Wyeast 1007 and trying to get cleaner, lagerlike ales). The other big kicker is the fact that I have no program logic controllers installed on my fermenters so someone has to manually open and close the jackets on the fermenters to control fermentation temperature. Does anyone have a link to a chart and or any reccomendations on how to get through to the owners of this place. I have waded through hell and remarkably managed to put out decent beers.

    I appreciate any help anyone might be able to offer.
    Last edited by mashhopper; 06-06-2006 at 07:17 PM.

  2. #2
    Join Date
    Oct 2005
    Caldwell, ID
    Wow. Where to start?

    Well, here is your chart:

    This is for Dowfrost, which is propylene glycol with some corrosion inhibitors.

    You can see that straight dowfrost has an SG of 1.05-1.06.

    First of all- what is your coolant temperature ?

    It sounds like you have a shell and tube evaporator. Very common. Depending on who you talk to the coils in the reservoir can acutally be considered atypical.

    You need to determine what is freezing up. Just because the outside of the heat exchanger (sometimes called the barrel) is frozen doesn't mean the glycol mixture is frozen. If the out surface of the heat exchanger the glycol piping and the compressor suction piping are less than freezing than yes you will get frost. This is not a bad thing. Let's say your chiller setpoint is 28 F, you glycol leaving the evaporator before dumping into your reservoir is like 18-23 ish, and your refrigerant temp is 0-10 F ish.

    Does the water ever stop flowing when you see frost? If not, you are not freezing.

    If you can't get the fermenters down to 44 F, your glycol probably isn't cold enough, and you probably aren't freezing the glycol. Your chiller maybe to small, your flow rates of glycol too small or uneven, etc.

    Your high tech temp control system doesn't help any troubleshooting either.

    Sorry this was kind of a ramble, the Nyquil is starting to kick in.

    Here are some things to check:

    1. What is the chilled water temp?
    2. What is the setpoint?
    3. Do you know if you have a flow switch
    4. If you isolate one fermenter, can you get that one down to temp?
    5. Pictures, model #'s, number of fermenters etc.

    By the way, almost any type of evaporator will be damaged if you freeze it up. It depends on how solid it gets, for how long, and how many times you do it. Even tank immersed coils can get wrekced by freezing (seen it).

    Rob @ Premier Stainless has a nifty little control system for multiple fermenters. It is expandable, the base system is preset for 4 tanks. You can expand up to 16 tanks with the one prewired enclosure, and do up to 24 tanks. They can be connected to a router so you can monitor on a web page and even remotely. When you get up to the larger tank #'s is cheaper than a bunch of smaller individual controller. He also builds super nice panel using individual process controllers. Good for 4-8 tanks. Depends on your budget and where you are looking to go.

    Good luck.

  3. #3
    Join Date
    Jun 2005

  4. #4
    Join Date
    Oct 2002
    I have not check the other references, but on the other side. If you are working with propolyne glycol, most chiller manufactuers recommend a minimum of 30% glycol up to 60% for various reasons.

    I would suggest you have your ref man come in and check the glycol(%, temp. protection) and the pressure settings for you R??? refrigerate/ temp. If not adjusted, then nothing works..... the way you want.

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