mash tun too small, ideas?

You could mash thick. A hair under 1 qt per lb should make it fit.

 

Yes, you'll need to sparge with more water.
Mashing thickness (within reason), in and of itself, shouldn't affect your efficiency dramatically. But mashing a bigger grain bill in general will, because after you've collected your normal pre-boil volume, there's more wort left in the grains than with a smaller grain bill. So you need to account for that, regardless of your mash thickness.

 

The alternative obvious choice is to do two consecutive mashes. Will take an extra hour or less, depending on how long you feel you need to mash.

 

I'd recommend BrewCipher. But I'm biased.

I have never noticed a correlation between mash thickness and stuck first runnings. There could be one theoretically, but I would not be overly concerned about it. If it gets stuck, re-stir and restart.

 

Thick mash and double batch sparge will get you what you want. And, you only need to mash once. The second two additions are just rinsing. Use 0.9 qt/lb for the mash, so that's like 3.5 gallons, the grains hold onto 0.1 gal/lb forever that you won't get back, so you'll lose about 1.5 gallons of that and be left with 2 gallons first runnings, so if you want a 5.5 gallon batch or whatever, you need an extra gallon for the boil, so that's 6.5 gallons, plus throw in another 2-3 quarts for trub and hop losses so that's 7 gallons, minus 2 gallons you got from first runnings leaves you 5 gallons more that you need from your sparges, so 5/2 = about 2.5 gallons per sparge. That's how to do it.

 

2.5 gallons of sparge might not fit with only 2 gallons of first runnings coming out of a nearly maxed out mash. Be ready to fit about a quart or two less and then add water to the kettle to reach desired pre-boil volume.

 

Not sure of your recipe but you could steep the grains that don't need mashing separately and add them to the kettle. Depending on what you're brewing it could buy you enough space in the mash tun.

 

Excellent point, it would be very tight and you might have to add more water later if it won't fit in the mash tun.

 

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