52 qt Rectangular Igloo Mash Tun concerns...

I have a 52 quart rectangular Igloo cooler that I'd like to use to make my first mash tun. The inside dimensions are 21"x11" and I'll be making 5 gallon batches with room to expand to 10 gallon batches.

Here's my concern:

The bottom of the cooler is flat and the outflow hole is 3/4" above the bottom of the cooler. If I install a copper manifold to drain through the outflow hole, there is an amount of liquid that will never exit the mash tun (unless I tilt the cooler). I calculated that amount to be 3 quarts or .75 gallons.

Is this normal? Or should I seek out another cooler for conversion. If possible I'd like to use this one because I have it already.

I've attached a few pictures for reference.

Well, that's correct if you don't consider that a lot of that dead space will be filled with the actual grains. Your wort loss will be considerably less than the total volume of space below the port. Figure out what that is, then use that in your calculations for mash loss (you may need to add an extra quart or so, but you'll probably just sparge until you reach your boil volume anyway, and that probably won't be at the last drop of your sparge).

If properly built and installed, a copper manifold will probably be the best system to use for your cooler.

The holes can be round drilled holes or they can be slots cut with a saw or cut-off disc. A staggered row of 3/32" to 1/8" diameter holes would work well. If cutting slots, be careful not to cut too far through the pipe. Slots 3/8" long and 1/4" apart should be adequate. The holes or slots should face down when the manifold is in use.

Experimenting with clear water can help you figure out the best way to connect your manifold to the cooler. Do what you can to avoid breaking the siphon when draining the wort out of the cooler. You should be able to siphon all but about a quart of water/wort out of your mash tun.

I place my manifold inside of two coarse strainer bags. The mesh of the bags creates a network of channels on the bottom of the cooler. These channels help the wort to flow freely to the manifold. I usually leave less than a quart of wort in the cooler.

I hope my description has been helpful because I do not have any pictures. Sorry.

You will actually get a lot of liquid below the port, once the wort starts flowing, you will have a siphon effect. When I calculate my mash + sparge water, I figure a quart for dead space and get my volume.

Here's mine; manifold made of bent copper tube, slots cut with Dremel cutting wheel:

Ryan450 said:

The bottom of the cooler is flat and the outflow hole is 3/4" above the bottom of the cooler. If I install a copper manifold to drain through the outflow hole, there is an amount of liquid that will never exit the mash tun (unless I tilt the cooler).

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I have literally this exact cooler for my mash tun. It is fantastic. Any cooler conversion MT will have some small space on the bottom, but it's really not that bad. Also, when it starts to be nearly drained, I do tilt the cooler, works great for me, never had problems with it causing grains to come out or anything. And as was already said, you can just top off with more sparge water until you reach your desired boil volume.

RDWHAHB

A "street"45 deg. fitting into the Tee fitting will put the manifold at the bottom of the MLT.

Great! I'm glad to hear this is somewhat normal and the siphon effect makes sense. With a 3/4" gap between the bottom of the outflow and bottom of the cooler, (working backwards here) I'll plan to direct the copper tube from the outflow at a slight downward angle meet the manifold somewhere in the middle of the cooler.

Now about compensating for the lost sparge... Do I have to add to the grain bill also, or just add about a quart to the sparge and drain until I get the proper preboil volume?

Ryan450 said:

Now about compensating for the lost sparge... Do I have to add to the grain bill also, or just add about a quart to the sparge and drain until I get the proper preboil volume?

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That's what I do... am getting a consistent 80% yield with mine

I used this exact same cooler with a cpvc manifold and it worked great. Just added a little extra water to hit my boil volume. I had to trash it when my ex used it when she cleaned out the freezer and she did not tell me for 5 days. I will be picking another up at Target tomorrow as I collect gear to get back into brewing.

Just to confirm... is this cooler size good for 5 gallon batches? I'm just brewing normal beer, no fancy stuff. Would a smaller cooler be a better fit? It just seems like the grain bed would not be very thick.

Ryan450 said:

Just to confirm... is this cooler size good for 5 gallon batches? I'm just brewing normal beer, no fancy stuff. Would a smaller cooler be a better fit? It just seems like the grain bed would not be very thick.

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I use it for ~10 pound grain bills. Works just fine.