Glycol - Testing and Proper Ratio

[Alphaacid]

My glycol unit doesn't seem to be able to cold crash my tanks fast enough. 10bbl and it takes about 2 days to go from 70F -> 36F. This is with one other BT maintaining 36F temp. I can not get any my tanks to go below 35F. I'm thinking my glycol ratio is off.

What tool do I need to test my glycol?
How do I know what the proper ratio of glycol to water should be?

[TGTimm]

A refractometer is fine for testing glycol. A hydrometer is fine too.

Your glycol mix will depend on your chiller set point. For instance, we run our chiller set to 26F. Manufacturer's recommendation is a glycol freeze point 20-25F below the SP, so our glycol is mixed ~35% by volume, for a refractometer/hydrometer reading of ~27 Brix.

More glycol=less heat carrying capacity and more expense.

[Starcat]

Glycol Complexities

The Best way to set glycol is by BRIX using a refractometer. I prefer the percision of this to a hydrometer for this kind of work.
We run about 29.
Based on your description you are dealing with other factors that are causing problems.
With that said. I'll offer some points on Glycol for future reference.
There are some good resources at Pro Refrigeration with charts etc. that will show you Brix and details.
When you have a Glycol chiller setup outdoors as most are, you have to consider the Ambient the machine is in for several reasons and you have to gauge freeze protection based on several factors including condensing AND evaporating temperature. Your low ambient controls have to be installed and configured with High Expertise or it can and will cause problems that people without HVACR experience and savvy will never figure out. You do need low ambient control on ANY chiller of any type.

Golden Rule -1 Too High Brix can be almost as bad as too low and can cause lockouts that are beyond the scope of this treatise.
As Timm has stated, Glycol is less efficient for heat transfer than plain water, your Brix will depend on where you need to run setpoint, and your machine environment and control settings alll tie in in a complex manner that will not work right unless its all set up well.
The only reason we use Glycol is to keep the heat transfer media from freezing with something that is not toxic.
Pumping efficiency is lowered with glycol solutions.

If your heat load calculations were correct for the load and your pumps and loop are set up correctly...... that is you have the right machine for the load you are running and there are not mistakes in your loop design, then the rest comes down to having the right controls on the system being dialed in by someone who totally understands the process.
There are all kinds of systems out " there " at large that are not really made for Brewery duty, they are set up totally wrong, and will never work correctly until major diagnosis and changes are made. The Thermodynamics of heat transfer unfortunately involves some math that has to be respected in relation to load and fluid flow rates.
Some jackets on some tanks defintiely outperform others. They are not all created equal and there are challenges along those lines that can be very unexpected. If you are in a hot ambient it adds insult to unjury. Your system has to be optimized for both summer and winter.
Slight control adjustments from summer to winter are common.

[Alphaacid]

None of the HVAC guys in my area have any idea how to calibrate my glycol properly, and I need to fix it. It's not running even close to efficient, getting my FV's down to 36F from 37F is a big accomplishment. At one point there was a glycol leak, and someone dumped pure glycol into the system, so I KNOW the brix are off.

Anyone have any suggestions? Should I figure out the glycol brix, and post all my parameters here in hopes of doing it with online help? Not being able to chill my beer to 33F costs me a lot in CO2 as well, as the cost of the inefficient glycol unit running.

[BroadWay411]

Don't use hydrometer

Don't use a hydrometer to take a reading of your glycol. Hydrometers are fine for ethylene glycol but will potentially give you false readings with propylene glycol. Here is a good read. Get a hvac refractometer.

http://www.reichertai.com/clientuploads/directory/download_pdfs/Reichert%20Why%20Use%20A%20RefractometeR.pdf

[wailingguitar]

None of the HVAC guys in my area have any idea how to calibrate my glycol properly, and I need to fix it. It's not running even close to efficient, getting my FV's down to 36F from 37F is a big accomplishment. At one point there was a glycol leak, and someone dumped pure glycol into the system, so I KNOW the brix are off.

Anyone have any suggestions? Should I figure out the glycol brix, and post all my parameters here in hopes of doing it with online help? Not being able to chill my beer to 33F costs me a lot in CO2 as well, as the cost of the inefficient glycol unit running.

First off, what do you have your chiller set to? If it isn't low enough and maintaining that temp, you are never going to get your tanks where you want them.

[Alphaacid]

Set point I think is like 29F, I'd have to go double check though.

Can I use a regular Brix refractometer to check the glycol?

[BroadWay411]

Set point I think is like 29F, I'd have to go double check though.

Can I use a regular Brix refractometer to check the glycol?

You can, yes. Here is a helpful chart.

http://mychiller.com/GlycolChart.html

[mmussen]

If your chiller is set to 29 that is probably a big part of the reason why your tanks aren't getting below 36. You need to have a fair bit of temperature differential between the beer and the glycol to drive heat transfer. The lowest my FV's will get is about 6 degrees above the glycol set point.
Make sure you've got a strong enough glycol solution before you turn the chiller down any - you really don't want it freezing up in the chiller.

Also, at a set point of 29 its unlikely but you may want to check after a transfer that you're not freezing beer on the inside of the tank. I've seen it before where a set point is pretty low and you end up with ice inside the tank where the jackets are. That ice will kill your heat transfer and keep the beer from cooling as well.

Good luck

[wailingguitar]

If your chiller is set to 29 that is probably a big part of the reason why your tanks aren't getting below 36. You need to have a fair bit of temperature differential between the beer and the glycol to drive heat transfer. The lowest my FV's will get is about 6 degrees above the glycol set point.
Make sure you've got a strong enough glycol solution before you turn the chiller down any - you really don't want it freezing up in the chiller.

This is pretty much in line with my experience, with a set point of 26F I get 32-33F in my tanks.

[TGTimm]

Yep--Pro refrigeration the maker of our chillers, recommends a set point of 26F.

Icing of the fermenter usually results from poorly designed/located jacket. Use the highest jacket that is fully covered by product, and the fermenter should establish a thermal circulation that will prevent icing. A low jacket will often cause the beer to stratify, with cold beer at the bottom and warm beer on top.

[lhall]

Just to clarify a point - your glycol concentration should be enough to keep the mixture from freezing at the SUCTION PRESSURE of the refrigerant. The refrigerant temperature at the suction pressure will be around 10-15 deg F depending on the type of refrigerant. If the glycol mix starts freezing on the refrigerant/ glycol heat exchanger you will have all kinds of problems. I know this from experience.

http://prochiller.com/wp-content/uploads/2016/03/AllAboutGlycol.pdf

[Starcat]

Remote Assistance

None of the HVAC guys in my area have any idea how to calibrate my glycol properly, and I need to fix it. It's not running even close to efficient, getting my FV's down to 36F from 37F is a big accomplishment. At one point there was a glycol leak, and someone dumped pure glycol into the system, so I KNOW the brix are off.

Anyone have any suggestions? Should I figure out the glycol brix, and post all my parameters here in hopes of doing it with online help? Not being able to chill my beer to 33F costs me a lot in CO2 as well, as the cost of the inefficient glycol unit running.

YES, read your brix, give photographs of your chiller system showing all pumps and controls, and I may be able to give you some points in the right direction. My reference in the former post to Evaporator range means the Saturated Suction Temperature the system is running at which will change and drop in response to a drop in outdoor ambient.
This is why those control settings are way more an Art than a Science and why not just any Junior HVACR Tech will have a grasp on how to deal with the total picture. Guys that have worked on chillers day in and day out for a living as in the " BIG ONES " will know where to go with this equation. As thus your Brix as it should be is going to be influenced and partially determined by the COLDEST ambient the Condensing unit is expected to hit during winter. This also affects how the LPCO is set and again a lot of people simply do not understand how to set a pumpdown control with respect to locality. Its not just about pumpdown. Its about where the Compressor inlet pressure is going to land in the coldest part of the run.
Take note of the current behavior of your chiller as its running now and let the forum know if the run time is more constant and ON a lot of the time, or if you are seeing shorter cycles. You may be right on the edge capacity wise, which will mean you have to get the fine tuning of what you currently have dead on. It is helpful to have a gauge on your Supply header in the plant so you can take note of the line pressure at different loads.


Star

[Alphaacid]

I reduced my set point form 29F to 25F, and the differential to 1F instead of 3F. The glycol went to 25F, I came and checked my BT's and they had ALL dropped from 37F to 33F, within 10mins.

Thanks!

[mmussen]

If the differential you changed to 1oF is the differential for the glycol chiller itself you'll want to widen that up again. Having such a small differential will cause the compressor to have to work for short bursts quite often - That's called short cycling and will greatly reduce the lifespan of the compressor.