Planning on building a wort chiller (immersion chiller) over the next few days with some birthday money. I went to lowes today and here are my options for copper:

1/4 inch copper tubing at 50 ft for 39 bucks

3/8 inch copper tubing at 20 ft for 37 bucks

Which would be more effective at cooling a 5 gallon batch? I know with quarter inch tubing flow rate will decrease, but more surface area present.

I just built one with 50’ of 5/8" and it’s very effective. Like anything else, don’t skimp and regret it. I’d go at least 3/8". The flow rate through 1/4" will be terrible. Bigger the better…

3/8 inch at 50 ft would be your best bet. This is what i made to cool 5 gallons with good results. Depending where you live, and the time of year, you’ll get the cooling results that you are looking for.

This is really going to depend on how much coil you can get underneath your wort. No offense to ACKBrew, but I believe he has the wrong of it here, don’t let anyone tell you this is about flow rate, this is really a function of how much copper surface you can expose to the wort. Thermal conductivity is all about surface area. In my own (very unscientific, admittedly) observations, I have lost very little cooling time when I cut my rate thru my IC in half at the faucet. This, as I said before, is more about giving the water the chance to suck heat from the wort. With 50’ of copper you have the opportunity to expose a lot more copper than with the 20’ of larger diameter. Here’s just a little math to back this up:

1/4" Diameter
0.25 (diameter of pipe) * 3.14 (pi) * 47 (length of tubing, less length for extrusions) * 12 (to convert ft. to inches) = 443 in2 of exposeable surface area.

3/8" Diameter
0.375 (diameter) * 3.14 (pi) * 27.5 (length of tubing, less lengths for extrusions) * 12 (to convert ft. to inches) = 381 in2 of exposable surface area.

Now much of this again depends on how much of the 50’ you can keep underneath your wort. If you make your coils larger and can keep much of the 1/4" below the wort, it should perform better.

Either way, both should help improve your cooling vastly! Good luck!

The reason 3/8" is a minimum isn’t just for the heat exchange math and surface area.

The main reason 1/4" is not practical is that it will be flimsy and very easily tweaked and damaged.

The second reason is resistance. Flow is very important, and if your water source can’t force enough water through the coil at the proper velocity to remove the heat that is able to be exchanged you have essentially bought coil area that is doing nothing. Once the cooling water reaches near saturation level the efficiency of the remaining coil is limited. Your chilling water should be leaving the coil ideally just a degree below the current wort temp so you are assured that it is removing the most heat possible.

As I have to deal with warm tap water temps here in Florida, I went through several pumps and coils experimenting. Chilling water velocity and the ability of any source to pump through at a proper force was critical. This becomes obvious when using submersible pumps, and seeing that the power of the flow is critical.

All that said, big durable copper coils are also a pleasure to use.

Surface area comes into play greatly when you’re talking plate exchangers, as the heat transfer is taking place on two equal volumes of water ideally flowing at the same rate. Correct you are about the greater surface area of a 1/4"x50’ coil vs a 3/8"x20’ coil, but the water has no way of flowing rapidly enough to be effective with a 1/4" coil. In plumber terms, if a coil in water heater is 1" and I pipe to it with 3/4", I’m not allowing the coil to work to it’s full capacity, resulting in poor recovery when it comes to hot water. The longer the coil, and larger the inside diameter of the tubing, the more effective it will be. There are many variables, but ideally, you want the MOST, COLDEST, water possible moving as FAST as possible through your wort to cool it rapidly. Common sense tells me that a 1/4" coil would take a long time to cool 5 gallons of wort, being the volume of the wort is so much greater than the volume of cold water (which won’t stay cold very long) in the coil. This is where there are many variable such as boils volume, incoming water temp, incoming water flow rate, etc… I wouldn’t go any less than 50’, and minimum 3/8" id. Years down the road you may find yourself moving to all grain, larger boils, whatever the case may be. In which case you’ll find this 1/4" chiller sitting on a shelf when you could have put the money towards a bag of grain…

BRITISH TERMAL UNIT: The amount of energy need to raise one pound of water one degree F.

Thanks for all the replies. Yeah that’s what I was thinking when I was at Lowes yesterday; made the smart decision and didn’t make a purchase. I suppose I’ll attempt to make a chiller with 3/8 inch diameter copper tubing at 50ft. Question is – where to get it at a reasonable price…

Purchased 50 feet of 3/8 inch diameter copper tubing today from lowes for $60. Used an old pair of washer hoses and a few clamps I had laying around. Took me 30 minutes to build (wrapped around co2 tank) and looks and functions great. Brewing a Murphy’s stout clone on Wednesday. We’ll see how much it improves cool down time!