Big difference between 1/4" and 3/8" diameter wort chiller?

Hello,

I'm a new brewer on a small budget. My first two batches have come out great, but I'm already tired of chilling my wort in a bathtub full of ice. I'm looking at immersion chillers, and the price difference between 1/4" diameter and 3/8" diameter is not inconsiderable. Does the extra eight of an inch make that much of a difference in chill time? Is it worth the extra money?

Thanks in advance,
Jesse

1x2" x 50' ftw. Make it yourself.

Thanks Henry. This is one of the options I'm considering. I'm still curious whether anyone has opinions about whether that 1/8" makes a difference.

length will make more of a difference than diameter... but diameter also makes a difference.

It will make a difference, noticeable for sure. Surface area is what counts, I think you can find a discussion of that on HBT (BobbyM ?). Of course if you've never used an IC, then you won't know about it. I have one of those small 1/4" IC's that I bought when I first started and it worked pretty well for 5 gallon batches as long as you stood at the kettle and moved the chiller around the pot while cooling. Don't bother making a massive sized chiller that extends way beyond the height of what's in your boil kettle unless you plan to upsize your batches in the future.

For 5 gallon batches, I'd be really happy with 50' of 3/8" OD.

I don't have any data but from my experience 3/8 is the way to go. 1/4 is just too small. For 5 gallon batches 25' of 3/8 is minimal. 50' of 3/8" would really work well. For 10 gallon batches 50' of 1/2" is fairly effective

I have 50' of 1/4" and it works fine for me. Helps that my ground water is around 60F in the summer. If you have warmer water, then the extra diameter will let you run more water through.

JesseL said:

Hello,

I'm a new brewer on a small budget. My first two batches have come out great, but I'm already tired of chilling my wort in a bathtub full of ice. I'm looking at immersion chillers, and the price difference between 1/4" diameter and 3/8" diameter is not inconsiderable. Does the extra eight of an inch make that much of a difference in chill time? Is it worth the extra money?

Thanks in advance,
Jesse

Click to expand...

That extra 1/8" equates to about 2-1/4 more cross sectional area in the tubing and that means more than twice the flow rate. The larger tubing will definitely chill faster everything else being equal. How much faster I don't really know as I have not done any actual testing. Only you can decide if the extra expense is worth it or not. The 1/4" will work OK for 5 gallon batches, but the 3/8" will work better. I'd go with the 3/8" if the budget will permit.

david_42 said:

I have 50' of 1/4" and it works fine for me. Helps that my ground water is around 60F in the summer. If you have warmer water, then the extra diameter will let you run more water through.

Click to expand...

Thanks for the info. I've always thought 3/8 was the minimum. I guess 1/4 can work also.

Also consider the structure of the chiller, the smaller stuff will just be all over the place. I've used 3/8" and 1/2".....obviously the bigger the better, but 3/8" will get the job done quite well if you stir with a sanitized spoon.

If you think you may ever want a plate chiller, now is the time. Buy the biggest and best you can afford the first time around and you will have that gear for many years to come.

Nothing's worse IMHO than re-buying gear because I bought lower quality/capacity stuff that will not grow with me.

JesseL said:

Thanks Henry. This is one of the options I'm considering. I'm still curious whether anyone has opinions about whether that 1/8" makes a difference.

Click to expand...

3/8 will have 50% more surface area for a given length than 1/4, and will have 225% more volume of water inside, that is substantial. Surface area and flow are what determine a chillers performance.

http://www.nybrewsupply.com/

Jeff sells them cheaper than you can make them. I also would recommend a 1/2". Gives you more flexibility if you want to expand later.

Captain_Bigelow said:

I also would recommend a 1/2". Gives you more flexibility if you want to expand later.

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+1 buy for the future... You will save $ in the long run.

Also, if you buy one, just go ahead and get one with the hose fittings. I saved a few bucks and got the one with just the tubing clamped on, and now I regret it.

My 25' 3/8 counter flow works great down to about 68 degrees depending on flow rate.Some galvanized T's, brass fittings, drilled out 3/8 compression fittings, and an old hose and BAMsaved enough to brew 10 gal of Pale Ale!

I have MW's entry level 3/8" 25' copper chiller. It will cool my 5 gallons of wort from boiling to ≤70F in about 20 minutes, using our 55F well water. This works for me.

The effectiveness of a chiller is going to be dependent on a bunch of variables: heat of wort, heat of cooling liquid, rate of flow, surface area in contact with coolant /wort, conductivity of material used in making chiller, and, to a lesser extent, things like the ambient temperature. I would have no idea which of these things are of greater or lesser importance. An engineer in fluid dynamics would probably be helpful in determining that.

wilserbrewer said:

3/8 will have 50% more surface area for a given length than 1/4, and will have 225% more volume of water inside, that is substantial. Surface area and flow are what determine a chillers performance.

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This led me to think that maybe it would be better to run 2x 50' of 1/4" tubing in parallel. Based on your math, the double 1/4" would have 33% more surface area for 11% less water flow. Plus the added bonus that the two 50' coils don't need to have the same cylindrical diameter (one coil could cool a central cylinder of the brew pot while the other could cool the wort closer to the side of the brew pot). For maximum efficiency, the tubing should always be in contact with the hottest part of the wort, so spreading to coils apart would reduce the chance of having the tubing in contact with wort that is already chilled

The price difference between 2x 50' of 1/4" and 1x 50' of 3/8" is not big and the efficiency / volume of water would be greater since it only depends on the surface area of the coils. Better performance and better efficiency, I might try that...

wilserbrewer said:

3/8 will have 50% more surface area for a given length than 1/4, and will have 225% more volume of water inside, that is substantial. Surface area and flow are what determine a chillers performance.

Click to expand...

Yep, Law of Laplace guides us here--r to the 4th power and all that. My head is hurting already from flashbacks of the physics classes. Go for the biggest diameter you can get. My homemade wort chiller was less than $50 for 50ft of 3/8', tubing, hose fittings and such.

Buy once, cry once...

Warning TECHNICAL POST AHEAD. I have taken courses on the analysis of heat exchangers and can do these calculations in detail. It is hard to simplify it without being so simple that i am not contributing.

You are going to see three big differences as your diameter increases.
Fairly obviously you have an increase in surface area as your diameter increases. More surface area means more heat transfer.

Second is that you will have a higher volumetric flow rate. This means that you have more cooling water coming through your wort chiller. There is an energy equation engineers use to analyze piping systems. This equation says that
pressure drop = (volumetric flow rate)^2/(diameter)^5*(loss coefficient).
Pressure drop is constant determined by your sink. Loss coefficient is dependent on the characteristics of your wort chiller.
A translation for the not math people is that volumetric flow rate is very sensitive to changes in pipe diameter. A higher volume of water flowing means faster cooling.

Thirdly you have an increased flow velocity. Each drop of water is moving faster. This means you have a higher convection coefficient on the inside wall. For the mathematically minded
Heat flow = (convection coefficient)*(Temperature difference)*Area
For the not math people this means that each square inch gives you more heat transfer.

The downside to this is that you will use more water if you have a larger diameter chiller. Use a counter flow chiller if you are concerned about this.

Every time you double the size of a pipe it runs four time the volume of fluids. Plus more surface area to transfer the heat. 3/8 is going to be a lot more efficient than 1/4.