Good points by everyone. It all depends on your batch sizes, grain bill, and brewing techniques--cmuzz, you'll have to figure it out for yourself as to what would work best for you. Some good rule-of-thumbs would be: 1.) for efficient grain bed lautering, the width should exceed the height, and 2.) a MLT that is approximately "double the volume" of your batch size is ideal, i.e., a 10 gallon round Igloo cooler for a 5 gallon batch size, or a 20.5 (82 Qt.) rectangular cooler for a 10 gallon batch size. The "double the volume" ROT also applies to BK size, as well.
I batch sparge. Almost always do single infusion or progressive (step) infusions like mash-in and mash-out. I don't usually fly sparge and I rarely cereal mash or decoct. One of the reasons was the limited capacity of my 10 gallon Igloo cooler when doing 10 gallon batch sizes. I did a weizenbock last month in the Igloo; I think the OG was around 1.090. Recipe used 33 lbs grain--filled it up to the 8.5 gallon mark when dry). Talk about a thick mash. Couldn't hardly stir the mash w/o making a mess. Lautering sucked (2+ hours) even with 1 lb of rice hulls. Mistake. Still turned out very well--but I can't get back the 2+ hours I wasted waiting for the lauter to finish.
I don't pour boiling water into my Igloo coolers--which might be stressing the plastic and causing the crack. My strike water usually is around 165F and it goes into the MLT (whether Igloo or Coleman cooler), then grist gets added and drops the temps down to the low 150F range. Hottest temp for sparge water might be 180 to 185 F when I'm transferring from the BK into the Igloo (HLT) in order to free up the BK for receiving the first runnings from the MLT. Nothiing hotter goes in the Igloo. I also don't use bleach or strong chemicals on the plastic coolers--just water from the hose. They are"pre-boil" equipment, so there's no need for the harsh chemicals.
I have a similar problem. I wanted to replace my 3 Gal Igloo Lauter Tun with a 10 Gal as I'm planning to go all grain. I'm buying 1 piece at a time & the Lauter Tun seems the place to start. I was researching prices & comparing the Rubbermaid to the Igloo. I noticed a disclaimer on the Rubbermaid, "Not Suitable for Hot Liquids."
I switch to the Igloo, same price & ordered it from an On-Line Store. I went to the Igloo Mfgr Site & used the Contact Us to ask if there was a problem with 160 Deg Liquids in the Igloo Cooler. 2 days later, after I had ordered the Igloo, I recieved an e-mail from Igloo Support saying that the Igloo Coolers were not suitable for Hot Liquids, That I would void my 1 year warranty & that the Liner or Shell would split because the Foam would expand with the Heat.
While I don't care much about the 1 year warranty, what good are they ayway, I'd rather not have the Liner split a spoil my Batch or the Shell split & be unsightly.
I've seen this same cooler (Yellow with Red Igloo & Red Trim) in many System Pics so how bad could it be? Then I saw at least 1 post here saying that there had been splits.
So, what say you all? Is there an issue with Igloo & Liner/Shell Splits if I am using Strike Water at 170 or less?
One other thing: I hate this Reply Editor. The screen jumps around the entire time I'm typing. Good thing I don't look at the screen until I'm done typing.