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**dick murton** · 11-04-2006, 07:59 AM

One deg C per hour is closer to the mark. Some yeasts will have started autolysing if held warm once the wort sugars are used up, some are more robust.

Also check wort oxygenation, and yeast food, particularly the oxygenation. Lack of oxygen wil rapidly cause yeast to die off early. If your wort is not bright just before pitching, the protein may cause the yeast to be "blinded" and therefore not flocculate.

Cheers

**RobZamites** · 11-04-2006, 09:15 AM

I think checking the specific gravity of your fermenting wort is the surest way to determine when to start crashing -- I'll generally go with 3 days at fermentation temp then start checking daily. Once the reading stays the same for 2 days consecutively, I'll do a VDK rest for 24 hours, then crash. I use WLP002, which is *highly* flocculant, yet still once in awhile, I have the problems you describe. I find time in a bright tank usually cures the clarity issues, though. BTW, I don't use kettle or serving tank finings.

**aswissbrewer** · 11-05-2006, 01:43 PM

Thanks for the replies guys. I'm getting closer, as always more than one issue is involved. Oxygen- point taken Dick: I'll try aerating my yeast shortly before pitching - I usually don't.
Just to clarify (the situation not the beer)- I don't use any finings either. Maybe I do have a wort protein problem?
Another thing - I close off my sparger at 18 Deg and build up carbonation as far as I can - around 2 bars. Does this make a difference?

What temp do you have in the bright tank Rob?
Do you also crash at 1 DegC/hour

Keeping on this refigeration track I still have a couple of questions:

1 Deg/hour is a lot of cooling power for me, I suspect I don't have it.

My chiller is filled with 1 cubic metre water which I brought down to 2.0 DegC to crash. I am in the process of buying some glycol.
Question: At what do I set my glycol temp in order to crash? minus 5 ? minus 10?
What temps do you use?

**jimvgjr** · 11-05-2006, 06:10 PM

glycol temperature

It is pretty typical to see our systems operating at 27 F (-3 C), but some breweries will want to run their glycol set point lower- like in the 20 F range.
Remember the lower the glycol temperature, the less BTU/HR your chiller system has the ability to remove. Also make sure your freeze percentage is 20 to 25 F lower than your set point temperature.

Good Luck.

Jim
Pro Refrigeration Inc

**RobZamites** · 11-05-2006, 07:20 PM

I've never tracked the cooling rate - I crash from 55F to 33F overnight though. Crashing happens in the fermenters, then the beer is moved to serving tanks for further conditioning. They're in a cooler at 36-38F.

Rob

**dick murton** · 11-06-2006, 02:07 PM

Re protein - the cold wort should be bright, OK, not as bright as filtered beer, but if you put a couple of alternating sheets of black and white paper together to make very sharp stripes, then these should remain sharp when you look through a couple of inches depth of the wort. The more blurred the edges, the more protein haze you have, and the more likely you are to have some sort of fermentation / yeast settling problem

The warmer you keep your glycol, providing the temperaure out doesn't rech the same temperature as the beer, the more money you can save. As long as you are extracting all the heat you can with that surface area of glycol jacket, there is no point in over cooling. You also stand a greater risk of forming an ice layer on the beer side of the jacket - which will completely wreck heat transfer characteristics. Ice is a pretty good insulator in comparison to liquid

**aswissbrewer** · 11-07-2006, 02:06 PM

glycol temperature

I'm filling my chiller with 25% glycol which will give me a freeze point of ca. minus 10 C or 14 F. My minimum set point will be minus 5 C or 23 F.

I have a pretty small operation and don't have a lot of tanks. So there are between times when I don't have to have the glycol down this cold.
Have I understood your advice correctly? When possible and reasonable it would be more efficient coolingwise to raise the glycol temperature.

Further, when I have to "crash" I could speed things up if I stepped down the glycol temperature parallel to the beer temperature?
For example:
Beer 64 F glycol 40 F
Beer 55 F glycol 32 F
Beer 45 F glycol 23 F
A sort of, chiller drag run? Maybe these tempertures are not the right ones but would stepping bring something when I'm trying to get the maximum out of limited horsepower?

**kugeman** · 11-07-2006, 02:23 PM

Is it possible that your flocculation problems are related to the manner in which you harvest your yeast? Are you pitching cone to cone, or are you collecting the yeast in a separate vessel (keg, bucket, etc...) and then repitching? What size are your tanks? How much yeast are you pitching?

If you pitch cone to cone you may be harvesting some poorly flocculating yeast from the top of the yeast pile in your cone (in addition to the good healthy stuff which settles in the middle layer of the cone). After 2 or 3 repitches it's possible that you've encouraged your yeast to be non-flocculent by continuing to selectively harvest this way.

I use whitelabs calif. ale yeast and this has happened to me before. Once it's happened there's not a whole lot you can do about it. Luckily I filter my beer so I'm able to remove the suspended yeast (it just makes filter day a PITA).

Just a thought.

**Sir Brewsalot** · 11-07-2006, 04:31 PM

My advice would be to set the chiller at a single temp - as high as your patience for chilling a batch will allow, and then forget it. Throttling the temp to match the load is too much thinking, and probably not what the unit was designed to do. I don't have a lot of tanks either, so I only operate the chiller when I'm looking to effect a change in tank temps. (Probably wasn't designed to do this either!) Temps don't creep up as much at this time of year when the whole damn place is cold!

Echoing what Dick and Kugeman were getting at: Definitely aerate. Grow ALL the yeast population and then you can crop enough of just the hi-floc stuff for the next round.

**dick murton** · 11-08-2006, 03:08 PM

As already stated, set the glycol temperature and leave it. Most people seem to find around minus 3 to minus 5 C works OK. preferably keeping it closer to minus three if possible to reduce unnecessary energy use in the compressors. Suggest setting it at minus five for a few brews. If that works ok, try setting it to minus 3.5, run for a few weeks, and so on. Depending on environmental conditions, it might just be possible to have a winter and summer setting, but if the insulation is good, there will be so little variation that it is not worth messing about with the seasons.

**Alex T** · 11-09-2006, 11:20 AM

hi,

sometimes, depending on your parameters (glycol temp, jacket area, etc) you can over do it. recently i worked with some 200HL tanks and they were taking more than two days to get to 4 degC. i found that when we reduced the glycol flow to these tanks that the cooling was actually more effective - ended up getting from 22degC to 4degC in 24hrs (so there was some icing on the jackets causing lack of heat transfer).

in my experience you should be able to set your glycol temp to -3degC and leave it, just adjust your tank's glycol flowrate until you get the desired effect. it may take a few batches to work out which way to go (i.e. more cooling, less cooling).

cheers,

alex

**aswissbrewer** · 11-13-2006, 10:14 AM

crash cooling

Well, I got my glycol and gave it the best I could. I'm almost embarrassed to report that I only managed to bring down the temperature at a little over 3 Deg C per day. From 16 C (60 F) to 4 C (40F) in around 3 days. Room temp is around 15 C (60F).

Originally I mistakenly thought that the lower the glycol temp the faster it could cool. Well that's one more thing I've learnt in these forums.

As for the other issues, - the cause of the flocculation problems. I have taken notice and am tipping the cropping procedure and the wort protein (new malt delivery) as the most likely causes, thanks guys. What stymied me was that everything worked well with another ale yeast. I still want to stick with the 1056 as I like the flavour and the attenuation so I'll try to work this out.

Crash cooling
I have the beer in what is essentially a conditioning tank. A horizontal 10 Hl tank , manufactured in Holland by DRU. These tanks are great for maintaining temperature but I suspect that they are not too good for "crashing". There are lots of these tanks in micros and brewpubs throughout europe. Anybody have experience with these or similar tanks?

**Sir Brewsalot** · 11-13-2006, 10:24 AM

Any idea what the temp of the glycol pipes leading to the tank are like?

I mean, if they aren't so cold, it's likely na issue w/ the chilling unit. If they are, it something on the tank side - maybe icing as described above, or even a clog in the line restricting the flow.

Cheers,
Scott

**jimvgjr** · 11-13-2006, 11:52 AM

Originally posted by Sir Brewsalot

Any idea what the temp of the glycol pipes leading to the tank are like?

I mean, if they aren't so cold, it's likely na issue w/ the chilling unit. If they are, it something on the tank side - maybe icing as described above, or even a clog in the line restricting the flow.

Cheers,
Scott

Great points Scott, another thing to check is the Temperature Difference across your jacket; the glycol entering temperature vs. the glycol exiting temperature. If the TD is high, it means that you are exchanging heat. A low TD, could indicate that your jacket is iced up (or jacket is undersized), and not allowing enough heat to be exchanged.

Is your chiller compressor running all the time, or does it remain off a majority of the time? If your compressor is not running a majority of the time, and your chiller isn't "calling" for cooling, it would indicate a heat exchange issue. If your chiller compressor runs constantly, yet your still not able to get the glycol temperature cold enough, it could be a mechanical issue with the compressor or perhaps the load is just too great for this compressor.

Good luck,

Jim
Pro Refrigeration Inc.

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