"crash" cooling

[aswissbrewer]

I'm not sure if I'm placing my question in the right forum but it definitely does have to do with refigeration.
Here goes:
I am brewing an ale using the american ale 1056 yeast. Just recently I started having flocculation problems - after only about 3 generations.

I have been advised to do primary fermentation at around 20 deg C and then to "crash" cool to induce good flocculation. This time round I probably missed the right time to crash but my beer stayed rather cloudy in spite of cooling down as fast as I could from 18 C to 4 C in about 5 days.

My question is : how fast do you have to "crash"
Are we talking about 10 Deg C / day or 3 Deg / day ?

What is the experience out there? What does it take cooling- wise to flocculate an american ale yeast?

[dick murton]

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]

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]

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]

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]

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]

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]

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]

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]

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]

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]

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]

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]

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]

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.

[aswissbrewer]

Thanks for the hints!
The compressor doesn't run all the time while I am cooling the tank and seems to handle the heat ok. So the problem must be tank side.

As to the temperature of the gycol line - that's a little tricky to measure. I had to unscrew the lines and measure the temp as the glycol flowed into a bucket. The glycol flows out with a good pressure so I guess it isn't blocked. In fact that's what made the whole process b----- tricky .

Example temps as far as I can tell:
Line into jacket temp: 2.5 - 3 C
Line out of jacket 3.5 -4 C
Glycol in chiller 1.0 - 1.5 C
Beer temp 7 C

I raised the gycol temp up over 0 C in order to rule out ice formation. (At least thats what I figured). No real difference.

What I do notice, is that the temperature of the beer comes down slowly and then if I do cut the cooling off with the thermostat the beer continues to cool and "overshoots" so to say. Ice ?

The tank thermometer is low down in the tank and I am also thinking that the settling yeast (some does settle) might be disguising the temperature a little? Possible ?

Be glad to hear from you guys again.

Steve

[Brew49411]

You need to check your gravity before you crash..... Don't just guess cause sometimes you'll get burned. When your within about 1 degree from your target crash that baby from 18 right to 4. Thats how I roll!

[jimvgjr]

The compressor doesn't run all the time while I am cooling the tank and seems to handle the heat ok. So the problem must be tank side.
This is definitely a good indicator, it could also be the result of lack of flow through the jacket- which would limit the amount of heat being exchanged.

As to the temperature of the gycol line - that's a little tricky to measure. I had to unscrew the lines and measure the temp as the glycol flowed into a bucket.
This is always a challenge to get good temperature readings, it is best however to keep the piping connected. When you removed the outlet pipe and let the outlet flow into a bucket, you likely reduced the line restriction and saw a greater flow than if the outlet pipe was connected to the fermenter- therefore your data might not reflect your normal operating TD across this jacket. Does that make sense??

There are inexpensive electric thermometers with small sensors that you can affix to the outside of the pipe, or the outside of the stainless fitting on our tank inlet and outlet (place some insulation on over these sensors). With a sensor on both sides of the jacket, you can monitor these temperatures at various times during the day to get a better idea of the TD across the jacket.


What I do notice, is that the temperature of the beer comes down slowly and then if I do cut the cooling off with the thermostat the beer continues to cool and "overshoots" so to say. Ice ?

The tank thermometer is low down in the tank and I am also thinking that the settling yeast (some does settle) might be disguising the temperature a little? Possible ?
Steve

I am not sure on this one, guess you should make sure that your solenoid is shutting off.

Good luck Steve!

Jim

[aswissbrewer]

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).

alex

Been having a few problems with my cooling system lately. Amoung other things a solenoid burnt out on me. This is one that stays in the open position when no power is getting to it.

This meant that the line was constantly open and subsequently when a thermostat on another tank cut in, coolant flowed through this solenoid as well. The tank was subject to constant but intermittent cooling.

What I noticed is that the beer temperature sank at a higher rate than if I had "crashed". It seems that the on-off coolant flow was more efficient.

Right on Alex T !

[Ted Briggs]

Two things to think about for effecient heat transfer:
--slower is better- throttle back the out flow for longer contact time. Make sure you dont exceed the tanks psi rating though.
--Less glycol is better- glycol keeps the water from freazing but reduces its heat transfer ablity.
Ditto on the point of selective harvesting of yeast. Try to crop your yeast early in the cycle to get faster dropping yeast. Basicaly this is genetic manipulation by selection. Though fast dropping yeast will probably be less attenuative!.....