Immersion Cooler Sizing

[BarefootFriar]

I spent some time in my local "Big Blue" home improvement store looking at copper prices this morning. I can get a coil of 1/4"x50' or a coil of 1/2"x20' for approximately the same price. They also carry 3/8" in both lengths, and the price for 20' falls between the two I mentioned.

My question is one of economics. For a few dollars more I can get a larger diameter pipe, but it will be 30' shorter. On the one hand, I would think the shorter length would be better because there is more volume inside it (because it's larger diameter) and therefore more thermal inertia. On the other hand, the longer one might be better because more surface area is exposed to the wort, thereby transferring more heat.

I'm no physicist, so I pose the question to y'all. Which one is the better choice?

What if I were to spring for the 3/8"x50'? Would that be preferable to the 1/2"x20'?

 

[mcwilcr]

The 1/4 diameter stuff is too small. The measurement is outside diameter so you are hardly moving any significant amount of water through it for efficient heat transfer. I have a 50' 3/8" one that I DIY'ed a few years ago and I have used it with no issues on batch sizes up to 11 gal. That being said, a 1/2" immersion chiller of the same length would be best but if your choice comes down to 1/2" x 25' or 3/8" x 50' I would go with the 50' option.

 

[Komocabo]

I agree with the 2nd post. I.bought a 50' stainless steel one on eBay a while back (3/8" x 50'). Chills 5 gals in about 20 mins or less. More surface area is preferred amd most manufacturers use the 3/8 diameter.

Another thought, after pricing the DIY method vs just buying a premade one, it ended up costing about $10 more to.buloy one... To me, $75 vs $85 was worth the expense for a few reasons:

1) it looks awesome, unlike some diy chillers that look warped... functionality is the same, but I want my stuff to look good... afterall, this thing shouldast a decade or more.
2) The ease of clicking a button and its at my door in a week... the anticipation is fun, and I don't have to go all over the store to find what I want.
3) Location... it costs me about $10 to drive into town.

If ten bucks breaks the bank, then go for it. DIY projects always bring a sense of pride too. Ecomomically, it made sense for me to just eBay the sucker...

 

[SagamoreAle]

It depends on your application.

I used a 3/8x20' for years back when I was doing extract brewing. It cooled a 10-quart pot in about 15 minutes.

If you're looking to cool larger volumes, get the 3/8x50'.

At some point, the larger diameter tubing will become less efficient and therefore less cost-effective due to a decreasing volume to surface ratio. Not sure if that applies to going to 1/2" from 3/8.

 

[HopChef]

I'm going to second the 3/8" 50' stainless option. Just dropped 5 gallons from 210 to 80 in 10 minutes on Sunday. Easy to clean, and should last as long as I take care of it. Amazon, $70.

 

[BarefootFriar]

Alright, that makes sense. If I can't swing the 50' quite yet, I'll set aside what I have and then maybe get it later.

Thanks for the help!

 

[TrubDog]

I have this.

http://www.amazon.com/dp/B000FDVD5S/?tag=skimlinks_replacement-20

Done!