Originally Posted by vitaminb
I'm not sure why a 2 gallon cooler tun would scale up to a 10 gallon easily. Could you please explain? I'm going all grain here BTW.
Sorry, I guess that wasn't very descriptive.
I was doing a good bit of all grain on the stove top using a 2 gallon cooler as a mash tun and really enjoyed it. I was suggesting that the added benefit is that a 2 gallon cooler should perform very similarly to a 10 gallon or 5 gallon cooler when a recipe is scaled up, so that anything you test and prove using a 2 gallon cooler should be very repeatable in 5/10 gallon batches.
The temperatures should hold very similarly and your efficiency should be very similar as well provided you're using the same type of screen and sparging process. I'd think that your volume losses would be very similar as well, or at least proportional.
That being said, to you original question, I don't think a 1 gallon batch would work well in a 10 gallon cooler at all. You're going to have tons of headspace above leading to a much larger temperature drop and I'd expect you'd have problems with a ton of wort being left behind in the cooler due to the much larger base size.