two-stage immersion chiller not chilling well below 100

[McKraut]

i started out all grain recently, and to go along with that, built myself a nice simple immersion chiller out of 20' 3/8"D copper tubing. it worked pretty well i thought, but had a tough time getting the temps down below 100F...

to remedy this, i went out and bought 50' of 3/8"D copper tubing, and made another larger chiller... this chiller i now use as the chiller in the brew kettle, and have the one i made previously as a pre-chiller which is in my sink immersed in ice water. the performance on the last two brews, however, was seemingly not much different than when i just used the immersion chiller by itself. once it got to about 100F, it took forever to just get down to about 79... i'm talking about 1 hour, which i don't find acceptable at all.

i was hoping to pitch at about 70F or so, but it just doesn't seem like it will be possible. any ideas as to what i'm doing wrong here?

 

[B2Barleywine]

It helps a lot to stir the chiller in wort as you cool. Doing this got me from 45+ min cool time to 15-20 min cool time

 

[MaxStout]

Maybe to troubleshoot this, determine the effectiveness of each component. A little experimentation may turn up some answers.

Measure the temp of your tap water (let it run a few minutes first). Then connect just the pre-chiller and immerse in ice water as you normally do. Run the water and measure its temp at the output. Is there a significant difference? If not, try some variations. Gently move the prechiller around in the ice water to maintain cold water contact. Measure the output temp again. Try adjusting the flow rate, and check the temp., etc.

Once you get a significant temp drop from the prechiller, repeat the test using both chillers.

 

[Andrikos]

You can stir the wort with a sanitized spoon while chilling to help with the heat transfer. Of course, a pump "whirlpooling" your wort will do a much better job.

Also, after you've cooled down the wort to ~100F (easy part) change over to pumping chilled water from another bucket filled with ice and water through the immersion chiller until you hit the 60s. Even pitching at 70F might be a bit too warm. I aim for 62F pitching temp and mid 60s for ferm temp.
If you don't have a pump, you can use a bottling bucket (filled with ice and water) at a higher level than the boiler pot and run icewater through the immersion chiller using gravity.

Even cheaper than that is using sanitized water bottles that have been in the freezer overnight in your <100F wort. But I never liked that method...

Best of luck.

 

[McKraut]

It helps a lot to stir the chiller in wort as you cool. Doing this got me from 45+ min cool time to 15-20 min cool time

i did stir quite a bit, and even gently hit the coils periodically thinking that maybe the colder water would tend to flow only in the middle of the coils. my goal though was to start a whirlpool though at some point and be able to leave it alone so the trub settled out at the center...

 

[McKraut]

You can stir the wort with a sanitized spoon while chilling to help with the heat transfer. Of course, a pump "whirlpooling" your wort will do a much better job.

what would that setup look like to incorporate a pump? what are all the advantages? i was hoping to just be able to start a whirlpool manually and leave it alone, and siphon it off avoiding most of the trub in the middle cone if possible... i'm not opposed to going that route if the results are drastically better, though.

 

[PDX_T]

do you have cold water going into the top or the bottom of the coil? I've heard that they work better if the water enters at the top.

 

[jbaysurfer]

Couple things:

1) agitate the ice in the prechiller.
2) Don't add ice to the prechiller bucket UNTIL you're well below 100F, you'll just be wasting ice
3) run the IC as wide open as you can early to accelerate the drop down to below DMS temps (140-150F).
4) SLOW the flow through the IC when you're approaching 100F and add your ice.
5) you MUST agitate the wort somehow. Either by stirring (stir opposite the flow of H20 through the IC) or pump (point the outlet hose of the pump so the wort crosses the IC coils increasing chill speed)

I got a lager down to 62 this way in less then an hour. I can routinely pitch ales in 40 minutes. Last little tip. What you find unacceptable in terms of pitch time, is routinely accepted by "No Chill" brewers. I don't recommend "No-Chill" but it's done with success. So RDWHAHB. Chilling time is relaxing time. Celebrate, clean up a bit, agitate your prechiller ice water, and agitate your wort. GL!

 

[nickw85]

I have something similar to the first setup with 25' of 3/8" copper tube I think. I run tap water through it and get 4 gallons from a boil to 70F in about 10 minutes if I stir it constantly then pull the chiller out and let it settle for a couple minutes. I get to about 110F in about 2-4 minutes. I only know that because I noticed last night when I was cooling a batch.