120qt Colman Xtreme. Is there such a thing as too big? I cracked my 10 Gallon rubermaid, and I am really trying not to buy a new one, and I have this monster in the garage chilling. I used to use it to help regulate my temps before I built my ferm chamber. I figured I could no-sparge a 10 Gallon Batch, and maybe batch sparge a buddy system 20 gallon? If I had the scenario set up, but IDK. Your thoughts? what kinds of trouble will I run into with such a monster mash tun?
The only real problem I know of is the dead air space in your large tun will have less thermal mass inside and thus lose temperature faster if I understand what i have read correctly. Like Denny, I use a 70qt for all my 5-6 gallon batches. I also used it for 10 gallons of pilsner with no issues. Bigger opens up more options for batch size and gravity as long as you can properly prepare for the heat loss(wrap it up?)
can I strike 1/2 way through mash with hot water to help compensate?
I guess that’s a possibility. Really thought somebody else would have jumped in here with some experience and ideas on a cooler that big. Sorry I can’t be much more help
Typically you size the cooler for the application, no?
Denny comes to mind immediately. He uses 2 or 3 different coolers depending on gravity and batch size. IIRC.
That’s true Derek, but in reality, his standard (and my) 70qt is really overkill for 5 gallon batches but it’s a good size that’s adequate for larger batches as well or high/super high gravity. Most of the round beverage cooler crowd are using 5-10 gallon coolers and get by for almost everything that do
Ok, help me with this, thermo isn’t my strong suit.
For the sake of this argument, assume the lid perfectly seals the air inside the cooler, no air can transfer between the inside of the cooler and the outside air. This would force all the heat energy to leave the tun through the insulation/cooler hardware.
If that’s the only way heat can escape, wouldn’t the larger temperature change of a smaller batch have more to do with the fact that it just has less thermal mass than a large batch?
Change the seal to one that isn’t perfect, and I can see the batch size making a larger difference in loosing heat. However, in my experience I’ve found that most coolers seal up very well.
As I’m about to dive into a cooler batch-sparge system, these have basically been my thoughts on small batches in larger coolers.
It seems to me that a small batch in a small cooler tun vs. a small batch in a large tun, the large cooler has more surface to transfer heat to the atmosphere. But then Thermo was a long time ago for me.
I guess you could, but that would throw off your pH and frankly sounds like too much hassle. How about just picking up a smaller cooler Long term, that’s gonna be the best solution.
I use my 48 qt. 90% of the time for the 5.5 gal. batches I do. Plenty of capacity for 5.5 gal. up to maybe 1.85-90ish. Higher OG or larger batch I use the 70 qt… Once a year or so I break out the 152 qt. for a 10+ gal. batch of BW. The great thing about that one is I can get in 65-75 lb. of grain at 1.5 qt./lb.
I thought I remembered you used 3 different tuns. I was starting to thinking I was crazy!
well, no comment on that, but you were right! 
Well when Denny says long term it’s better to get a smaller cooler, I think I have to listen to the man.
Well it was a thought, off to find me a cheap cooler. thanks for the help btw everybody.
True, and based on that I’ll probably start with a 48-quart, and get a 70 quart after I’ve a better idea how to ferment 10 gallons at a time.
I’m just curious about the underlying physics of it all. More insulated area to lose heat through makes sense, but brings up the question of is it better to buy a large high-end cooler rather than spend the money on two? (I’m thinking the answer is likely no, but what fun is that?)
A couple of months ago I spotted a 40 quart rolling Coleman square cooler at Ross Dress For Less for $17. It was in the size range that would be perfect for my needs: mostly three to four gallon batches. It was the only one that I’ve ever seen there and I snatched it up. I got around to converting it to a mash tun last week and plan a four gallon pilsner on Thursday. Talk about easy: I unscrewed the drain plug that it came with to discover that it was exactly the same size as the SS ball valve I had to install. I very carefully screwed it in, tightened the washer and nut on the inside and tested for water tightness. Nine hours later the water level was exactly the same.
I also found a 28 quart one at Goodwill for eight bucks that I never drilled a hole through before I got the 40 quart one and converted it. I might still do that some day or maybe I’ll end up donating it back to goodwill.
Even if you don’t lose significant heat with a ginormous cooler, those things are a real pain to clean. They’re heavy and unwieldy, and scream about pending back strain. I use the smallest tun that will hold my mash, either a 48, 70, or kayak size.
It would seem that a smaller cooler that is fuller will have a larger thermal mass, and therefore be more resistant to temp change, than a larger cooler that’s not as full and has a smaller thermal mass.