Is my Mash Tun too big?

[MatchstickBrewingCo.]

Hey Everyone. So I'm torn between going to BIAB or just going straight to All-Grain and have been looking into converting the cooler that I "borrowed" from my parents a couple years ago into a mash tun. The only thing is, I'm worried that it's too big.

I'm pretty sure it is either a 70 or a 100 quart rectangular cooler but I only plan on making 5 gallon batches at a time. I read on John Palmer's How to Brew site a while ago that having a mash tun thats too big isn't good but I was wondering why and what the effects would be. Does anybody have any experience in this or consistently use a big Mash Tun?

Any input would be great as I'm thinking of doing the conversion sometime soon (if I do it at all).

Thanks!

 

[DNKDUKE]

Does this 30 pounds of grain make my tun look fat?

 

[user 163849]

I have no answer but the same question only the cooler that I am thinking of using is a 70 quart version of the Igloo Cube.

 

[DNKDUKE]

OR

"I like big tuns and I cannot lie..."

SORRY.......

 

[dude3516]

You will have some extra heat loss, probably about 2 degrees worth given all the headspace.

The real question is how you plan on using the tun? If you are fly sparging the grain bed depth is something that does matter. If you're batch sparging then not so much.

edit: Fly sparging, get something smaller. Batch sparging, doesn't matter that much.

 

[30Bones]

I use a 70qt for 5 gallon batches and the only issues I see is the rare "small" beer 1.040 or less the grain bill gets really small. For that I might do BIAB so I can goose the heat when needed. Heat loss is only really an issue for me in the colder months, but I try to mash inside if it's really cold

 

[MatchstickBrewingCo.]

I plan on mashing outside too and its in the 20-40s until later in March. Maybe I'll just make a point of keeping some extra hot water around in case of too much heat loss. Thanks for the help guys... especially DNKDUKE for the chuckles :cross:

 

[jtratcliff]

If you find something insulating to lay on top of your grain bed during the mash, you can minimize heat loss to the large head space. Lay some aluminum foil on top, then a big chunk of styrofoam, for instance. Maybe find a cheap styrofoam cooler whose lid fits inside your cooler.

Also insulate the lid with some expanding foam. Most lids aren't as well insulated as the cooler bodies.

 

[Singletrack]

Also insulate the lid with some expanding foam. Most lids aren't as well insulated as the cooler bodies.

...but first do a search about insulating lids with expanding foam. Some have shown that it doesn't work well because it never really expands.

 

[Btaz]

If you find something insulating to lay on top of your grain bed during the mash, you can minimize heat loss to the large head space. Lay some aluminum foil on top, then a big chunk of styrofoam, for instance. Maybe find a cheap styrofoam cooler whose lid fits inside your cooler.

Also insulate the lid with some expanding foam. Most lids aren't as well insulated as the cooler bodies.

I use a large cooler 100qt? For 5g batches and batch Sparge. The tricks that seen to work for me are. 1 pre-heat the cooler with some hot water ~180F for 10-20 mins. Drain this. 2 place some rigid foam over the mash (1/4" seems good enough so far) 3 don't peek into it too often (stir every 15 mins or so)

 

[Btaz]

If you find something insulating to lay on top of your grain bed during the mash, you can minimize heat loss to the large head space. Lay some aluminum foil on top, then a big chunk of styrofoam, for instance. Maybe find a cheap styrofoam cooler whose lid fits inside your cooler.

Also insulate the lid with some expanding foam. Most lids aren't as well insulated as the cooler bodies.

I use a large cooler 100qt? For 5g batches and batch Sparge. The tricks that seen to work for me are. 1 pre-heat the cooler with some hot water ~180F for 10-20 mins. Drain this. 2 place some rigid foam over the mash (1/4" seems good enough so far) 3 don't peek into it too often (stir every 15 mins or so)

 

[jtratcliff]

...but first do a search about insulating lids with expanding foam. Some have shown that it doesn't work well because it never really expands.

Well then they clearly used NON-expanding foam...

 

[Stealthcruiser]

...but first do a search about insulating lids with expanding foam. Some have shown that it doesn't work well because it never really expands.

^^^^^^ This!
The "Great Stuff" in a spray can,needs contact with ambient air and moisture to fully cure.
I made one HELL of a mess in my shop floor, trying to replaced the collapsed , matted insulation in the cabinet of a cafeteria style milk chiller!

The void was 2 inches thick, 10 inches deep, and 30 inches tall!

Dow Chemical refunded my money for the 5 cans of "stuff", after I called raising hell about it, and that it doesn't tell you the "limitations" of the product, on the "directions" on the can!

 

[AirAssault]

I use a 70 qt Coleman xtreme for 5 gallon batches with no problems. These coolers are insulated very well and I always maintain my temperature during a 60 minute mash. I do preheat it though. My only complaint is how much room it takes up.

 

[BridgewaterBrewer]

I have a cooler mashtun but mainly do BIAB so I would recommend you try BIAB before converting the cooler. Check out this thread.
https://www.homebrewtalk.com/f244/please-help-old-hand-understand-biab-514282/