Minimum size needed for Igloo cool mash tun?

[RipCity]

I am looking to build a rectangular style igloo cooler mash tun. I have a spare cooler that is 21"x11"x10" (10 gallon/40qts).
Is this large enough for 5 gallon batches?

[brewinhard]

I use a round orange gott cooler that is 10 gallons and it works fantastically. Your cooler is perfect for infusion mashing. Now get to brewing on it!

[snowcapt]

Yep

[siwelwerd]

40 qts will be large enough for all but the biggest. I have a 48qt Cube, and have filled it to the brim for a 5 gallon batch of a 1.110 RIS. You should be able to squeeze in anything under 1.085.

[RipCity]

Cool.
Thx for the info.
Sounds like most people use false bottoms for the round tuns and ss tube mesh for the rectangular.
Anyone have any luck just using a el grande grain bag?

[spiderwrangler]

Sounds like most people use false bottoms for the round tuns and ss tube mesh for the rectangular.
Anyone have any luck just using a el grande grain bag?

I use a circular SS braid in my round 10 gal cooler, works great. I have used the bag before, but not much. One time I would give would to have a larger diameter bag than you do vessel. Otherwise the grain and bag sits off to one side and you have liquid on the other...

[Beer_Baron]

Cool.
Thx for the info.
Sounds like most people use false bottoms for the round tuns and ss tube mesh for the rectangular.
Anyone have any luck just using a el grande grain bag?

I used to use an el grande curtain... It was made of the polyester mesh that folks use for BIAB material. I used it to line my bottling bucket when I wrapped it in insulation and used it as a mash tun. Now that I have a cooler mashtun I use a SS braid. If you use fabric, it works much better if you have some sort of false bottom to create dead space under the material - I used a steamer basket.

[foomench]

PSSP false bottom in a 48 quart Ice Cube:


Here it is with 26.5# of grain, with a little room to spare:


I regularly brew 10 gallon batches with this. With a 40 quart cooler you should be fine for 5 gallon batches.

I think you need something to supplement the bag as alluded to, so you have some dead space. If you just throw the bag in the cooler I think you would be drawing disproportionately from the side where the drain plug is. A braided tube or slotted manifold are reasonable options too.