Immersion Chiller Taking Too Long

I brew 3-gallon batches, doing full-wort boils in a 5-gallon pot. I did the ice bath thing for a while but got sick of lugging 12 lbs of ice up the several flights of stairs to my apartment and having to wait almost an hour for my wort to chill to pitching temps. So I bought an IC, after reading how they're quicker than ice baths and less wasteful of H20, etc. Well, my experience thus far has been unimpressive. It still takes me a good hour to get my wort to pitching temp, and I really can't seem to get it any lower than 76°F. The chiller's a bit too big for the pot, so there's usually a coil or two of the tubing sticking out, but I can't imagine that makes a whole lot of difference. My tap water is usually around 60 to 65°F. I adjust the water flow rate to maximize the temperature of the water exiting the tube; usually it's barely above a trickle. I'm also stirring the wort frequently, which I'd prefer not to do b/c of the contamination risks.

So, my question: I'm sick of wasting so much time chilling the wort, especially because the kitchen sink is tied up the whole time. Any ideas why it takes me so long to get the wort down to pitching temps with this setup? Would a chiller made from a longer length of tubing, and thus having more coils, make a significant improvement? Would compressing the chiller I have, so that all the coils are submerged in my shallow pot, make a significant improvement? Or should I just bite the bullet and get a CFC (which will also require a new kettle with a spigot)?

What length and diameter is the coil? Did you say that you turn on the water that flows through the tube, just barely above a trickle?

I use a submersible aquarium pump in a cooler of ice water to recirculate the water through the IC and get down to pitching temperature pretty quick. Pump cost me about $20-$25 off of eBay.

tally350z said:

What length and diameter is the coil? Did you say that you turn on the water that flows through the tube, just barely above a trickle?

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20', 3/8" diameter. Yeah, just barely above a trickle.

Turn up the flow of the chill water. Having it as just a trickle is probably the entire reason your chill time sucks so bad.

Water flow is definitely an issue. You are supposed to run water through the IC at a good clip, like half bore at least, since the job of the chiller is to take away heat from the wort.

As was also said above a good investment would be a five gallon pail, a small pond pump (got mine at home improvement store for about $25. I've been using this set up (with 5 lbs of ice & water in pail) for five gallon batches and it gets cool in about 15 minutes.

I'm going to graduate to do some ten gallon batches so I'm gonna invest in a CFC utilizing a similar set up just a bigger pump.

Golddiggie said:

Turn up the flow of the chill water. Having it as just a trickle is probably the entire reason your chill time sucks so bad.

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This.

Cheers!

Maximizing the exit temperature will minimize the amount of water used, but also increase the amount of time it takes to cool. If you turn up the flow until the exit temperature doesn't drop any more, you will have maximized the heat transfer for your setup.

Do you stir or just let the water run? I have found that stirring makes a big difference.

+1 to turning up the pressure, I run mine pretty quick at first then back it off as the temp comes down to 120 range. As the summer approaches I'm going to try a prechiller with some ice blocks I think that will also help.

igliashon said:

20', 3/8" diameter. Yeah, just barely above a trickle.

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Problem solved. Trickle means the water will heat up and carry the hot water through 20' of copper. When on full pressure, the hot water is carried out.
Use a pond pump and a large plastic bin to recirculate ice water when the exiting water temp is around 125. I usually get down to 68 in 15 minutes.

I use a 50' ss ic and get 10 gal batches down to the mid 60s in 15 minutes max with tap water. Good flow rate through the chiller and stirring the wort help. I whirlpool with my chiller and just keep the wort moving and try not to splash. If you dont stir or move the wort it will take forever

I've been effectively using an IC for almost 20 years. The larger the temperature differential between the wort and the cooling water, the faster the heat transfer. You can flow at a good clip when the wort is real hot but once the wort gets down to 100-120 the heat transfer slows considerably. The best way to speed up the last 50 degrees is by circulating the wort, either by stirring, whirlpooling with a pump, etc. The most important thing is to keep the wort moving.

Faster flow and keep stirring the wort.

I use a spiral grout mixer attached to a big 1/2" electric drill inside a 50' 1/2" IC to cool my wort. I've cooled down 12 gallons of wort with that thing down to sub 70F inside 10 minutes. Its a beast. I think we used that and maybe one more chiller to cool down a 60 gallon batch of framboise!! The key is maximizing the delta between the water temp inside **THE ENTIRE** chiller, and the wort touching the outside of the chiller.

You can minimize the temperature of the water in the entire chiller (not just the first few feet) by increasing flow. A crap load more not-so-cold water is better than ice cold water entering the chiller and trickling out super hot. The ice water quickly heats up and you really only get use out of part of your chiller. If your ground water is not below 70F, save your ice water for the last few minutes to help drop the wort temp down under 70. Use higher flow tap water to knock the wort down from 212 down to 90 or so.

The grout mixer constantly stirring the wort is another key. It vigorously stirs the wort around the chiller so there can be no cold zone formed around the chiller. If you dont stir around the liquid, the wort directly around the chiller becomes cold and the delta between the water inside the chiller decreases.

cliff notes, crank up the volume and stir the crap out of your wort.

Happy chilling!

Ha ha, thanks guys! I'm a walking case-study in the dangers of having "just a little" knowledge. I figured that the hotter the water exiting the chiller, the more heat it was carrying away from the wort, and that that would make it faster. But if everyone else is using higher flow-rates and getting chilled faster, then clearly I don't know what I'm talking about! I'll try it faster next time and see if that helps.

This is definitely one of those times where I can be 100% certain. Increasing the coolant flow will reduce chilling time. I'd bet you 100,000 bucks.

It is absolutely true. Heat transfers between the water and wort through the copper at a rate that is determined by the difference in temperature (delta). The thought that is missing, is that temperature differential can be calculated at any point along the entire length of the chiller. You could actually do that and make a graph showing the chiller water temperature increase vs flow. Or maybe flow rate vs wort temperature drop rate

Anyways, The ice water goes in at 32F, but 1ft down the tube moving at slow speed it may already be 150F. Now the temperature differential for the remaining 19ft of your chiller is only a few degrees. If you pump in ice water at a very high flow rate and it comes out of the chiller at 33F, that means the temperature differential was very large throughout the entire chiller. It transfers heat faster, but you use A LOT more water. The limiting factor of your chiller would be the thermal transfer limits of wort, through copper tube, into water. The water temp cannot go (much) below 32F (yeah, salt, etc)... so flow is the only other factor here. I'd love to see someone make a glycol powered home immersion chiller! HAHAHAH!!!!

So some people use bigger chillers. The reason is they have more surface area to transfer heat and can more flow more water given the set constant pressure (house water pressure). When water comes out of the chiller noticeably hot it means two things. One, your chiller is working and its removing heat from the wort. Two, you could increase water flow and drop the temperature of the wort even faster given the same coil. In other words your copper tube is efficient enough at heat transfer so that the water significantly heats up, and makes the temp delta smaller, by the time it exits.

I just thought of something actually. I use a 50ftx5/8" garden hose to my chiller, and a 50ftx5/8" drain hose to get to the street. Thats 100ft of garden hose, plus 50ft of 1/2" copper. If I used shorter hoses, my flow rate should increase! Maybe I only use a 10ft hose to get to the chiller and use a 20ft hose to just get the water half way down the driveway. Pressure drop will be less and technically that would increase flow. It may be that most of the restriction comes from the 1/2" copper and elbows though, and I would gain like 1% or some miniscule amount of efficiency. Now a 3/4" hose going into a 3/4" chiller... maybe the flow restriction becomes the spigot or the copper feeding the spigot. heh heh...

1" hose and 1" copper chiller!!

Faster flow, as said. I actually run a 3/8 one inside an ice bath in a bucket then run from that one to my chiller in the wort.

Chest freezer with pond liner filled with salt water would be fine!

yeah... plate chillers and counter flows use a different approach... divide and conquer! Immersion chillers use a brute force approach.

Okay, this makes sense now. If I'm trying to maximize speed of chilling, I want the entire chiller to stay as cold as possible so that more of it will pull more heat from the wort faster. If I'm trying to minimize water usage, then I want the water to pull as much heat as possible per volume of water...but this will actually be a very slow process. So I was on the right track to minimize water usage, but that's the wrong way to maximize speed of chilling. Awesome. My education in physics takes a tiny step forward. Thanks for the thorough responses!

So, let me see if I got this straight: for fastest chilling, ultimately what I want is for the tap water to come out at the same temperature it went in, right? So to minimize waste water, my flow should be just fast enough for output temp to equal input temp?

Well, probably the most water conscious method would be recirculation using ice. Unless you are using snow or something naturally formed, you are just trading electricity for water conservation.

igliashon said:

So, let me see if I got this straight: for fastest chilling, ultimately what I want is for the tap water to come out at the same temperature it went in, right? So to minimize waste water, my flow should be just fast enough for output temp to equal input temp?

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If you are talking about this with an IC then no, you want the exiting water to be warmer then the input water! The hotter the better since that would indicate more heat is being pulled from the hot liquid!

The idea behind an IC is the cooler liquid in the coil will "draw" the heat from the warmer liquid so as the liquid in the IC moves through the coil and exits, the heat that was transferred to the cooler liquid then exits the coil!

The higher the rate of flow through the coils the more heat is able to be "drawn" from the hot wort however, there is a point when you can have so much of a flow rate that you are not drawing any more heat than the volume of liquid exiting can handle. Basically, if you run the water at full speed you are wasting a lot of water.

KevinW said:

If you are talking about this with an IC then no, you want the exiting water to be warmer then the input water! The hotter the better since that would indicate more heat is being pulled from the hot liquid!

The idea behind an IC is the cooler liquid in the coil will "draw" the heat from the warmer liquid so as the liquid in the IC moves through the coil and exits, the heat that was transferred to the cooler liquid then exits the coil!

The higher the rate of flow through the coils the more heat is able to be "drawn" from the hot wort however, there is a point when you can have so much of a flow rate that you are not drawing any more heat than the volume of liquid exiting can handle. Basically, if you run the water at full speed you are wasting a lot of water.

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Wasn't this what was just debunked? If the water is exiting hot, that means it's heating up in the coil, thus lowering the temperature differential in the parts of the coil closer to the exit, thus reducing cooling efficiency. If you want max temperature differential along the full length of the chiller, then the water exiting should be cool, indicating that the full length of the chiller is maximally cool and thus the temperature differential is maximized. If that's correct, then a faster rate should cool it faster.

How I make sense of it is to think like the chiller is an ice cube. If the water heats up halfway through the chiller, then that's like there being an ice cube half the size of the chiller, since the warm half of the chiller isn't chilling anything. If the water stays cold the whole way through, it's like an ice cube the whole size of the chiller. So the longer the water stays cold in the chiller, the bigger the ice cube, which means the more cold surface in contact with the hot wort, and the faster the cooling.

So what I want is the minimum flow rate possible that will keep the chiller maximally-cool, I'm pretty sure.

HAHAHAH! Its funny how something so seemingly simple can be over explained to like the 100th degree. Its like a plane on a treadmill.

The ice cube analogy is a good way of looking at it. You have the potential of having a 20ft ice cube. Given that inlet temperature is the same, the only thing that controls how much of that ice cube you really get is flow. If you flow slow you get lets say a 1ft ice cube. If you flow fast maybe a 10ft ice cube. Realistically, It's not possible to get a 20ft ice cube given a 180F temperature differential through a 3/8-1/2" soft copper tube. The amount of water you would need is not available at house water pressure, and it would blow the chiller up if you somehow generated the pressure to achieve that flow rate.

Lets see if I can come up with some other overly scientific way of explaning this. You have thermal energy stored in this wort. What we are doing here is removing it from the wort and placing it in chiller water. Lets roughly calculate how much heat we are talking. By definition, a BTU is the amount of energy required to raise one pound of water one degree F. How many pounds does 1 gallon of wort weight? Well if it was pure water it would be 8.34 pounds, so for the sake of not complicating this more (HA!) lets use that. We have a 5 gallon batch of wort here so that's 8.34lbsx5gal=41.7 pounds of wort. Lets see how many degrees we want to remove, roughly. 212F-65F=147 degrees. So 147*41.7=6130 BTU if energy we need to move. Notice I did not mention time at all here. It doesnt matter if you do this over 10 minutes or a year. We still need to move 6130 BTU.

Now, lets say the tap water is 50F. We take that 6130 BTU and put it into 10 gallons of chill water. What would the average temperature of the chill water be after it chilled that wort. So we need to calculate the temperature increase. 10 gallons of water weighs 83.4lb. 6130/83.4 = 73.5F temp increase. 50F + 73.5F = 123.5F average temperature of the chill water. Thats pretty hot.

Lets say we use 100 gallons of chill water. Without going through all that I can tell you the temp increase will be 7.35F. 57.35F average temperature of the 100gallons.

That's why when the water flows faster its cooler. You are spreading out the thermal energy of the wort over more water. The temperature increase will be less in each molecule of chill water, but you are still removing all of those BTU's from the wort.

Well done, sir! And props for mentioning the plane on a treadmill. Hi-lar-i-ous!

I started using the paint-mixer/cordless drill approach to stirring (as opposed to hand stirring) and my cooling times went down dramatically. Easily 50% decrease in time.

I have crazy high water pressure and cold water. My 20-some feet of 5/16 copper produces water at the exit that is only a little warmer. I could get by with less water volume - perhaps i should install a valve on the inlet hose . . .

daddyo said:

I started using the paint-mixer/cordless drill approach to stirring (as opposed to hand stirring) and my cooling times went down dramatically. Easily 50% decrease in time.

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Does this also aerate the wort?

BrewScout said:

Does this also aerate the wort?

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It would pretty much have to

Bobby_M said:

Chest freezer with pond liner filled with salt water would be fine!

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Bobby,

I am going to be using a pump for the first time in a chest with ice water. Why are you using a pond liner?


Great thread, learned a lot!

I don't actually use a chest freezer as a reservoir, it was just an idea. However, I don't think the liner of freezer is really meant to be 100% waterproof even though it may hold for a while. I'd either paint on a membrane type waterproofer or line it with something for long term use.

Those of you who use the recirculation pump and ice bucket method - are you starting out with this from the start (ice included), or do you start once-through and then switch partway through?

I would just think that you'd blow through all your ice just in dropping the first handful of degrees, no?

I'm dismayed by the amount of water I waste in a not-very-fast-anyway chill using once-through water so I'd like to look into this, but I just wonder if I'm over-thinking it.

Thanks

ResumeMan said:

Those of you who use the recirculation pump and ice bucket method - are you starting out with this from the start (ice included), or do you start once-through and then switch partway through?

I would just think that you'd blow through all your ice just in dropping the first handful of degrees, no?

I'm dismayed by the amount of water I waste in a not-very-fast-anyway chill using once-through water so I'd like to look into this, but I just wonder if I'm over-thinking it.

Thanks

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I run water from hose into chiller and the warm output is saved into a bucket for later use. Cleaning or watering garden.
When exiting water cools down, i collect water into 18 gallon Rubbermaid tote. Fill about 1/2 way. Disconnect chiller from hose and attach to pump and fill up Rubbermaid tote all the way with ice. Recirculate until I hit about 67. All done.

Right, get the wort down to 120F on tap water first, then switch to icewater. The ice poundage requirement goes way down.

Cold water with a higher flow is important. Besides stirring, you can also slowly move the chiller around in the wort and get a lot faster cooling. Same idea as stirring the wort to break-up temperature gradients right around the chiller tubing. Monitor the temperature of the water out of the chiller and compare doing nothing (no stirring or moving the chiller) to some movement (either stirring or moving the chiller).

Well, I brewed yesterday, and y'all were totally right! I cranked up the water flow till it was as cold as I could get it coming out the end, and stirred a bit every few minutes, and I hit 80° in 15 minutes. I was so blown away I almost forgot to rehydrate my yeast! Man, what a difference!