5g batches, 10g MLT Too much headspace?

Since the arrival of my 2nd child, the opportunities to brew have become sparser. I've resorted to 10g batches, but in reality, I'll only be doing that a few times a year, mostly I'll do 5g batches. I'm thinking of buying a 10g cooler for my mash tun and using my 5er for HLT. Will I have too much head space in the 10g cooler when I do 5g batches? This will me most of the time. Will it drop my mash temps too much? Thanks.

You'll be fine. My MLT is a 40qt, and I brew 5G batches. Just invest in a well insulated one like a Coleman extreme or the round rubbermaid one from Home Depot.

IMO, 10 gallon coolers are pretty much the minimum for full-range 5 gallon batches. I've always felt that 5 gallon coolers are really only useful for partial-mash, and small AG.

I mash in a 48 Qt Igloo rectangle, and have NO problem with 5 gallon batches, whether small (1.033 OG) or large (1.088 OG). I even used my 48qt for my Barleywine, 3 gallons of 1.105 OG.

You'll be fine. If your mash temps start fluctuating, double-check your strike temp with software - in BeerSmith, there's a check box to automatically adjust your strike temp for a non-pre-heated cooler.

I want to upgrade to at least 70qt - still for 5g batches.

I recently bought a 10g cooler (because Home depot actually had them, and on sale).
I brewed 3 batches in it. One batch sparge, and two fly sparges. In each case, the mash went perfectly with no temperature issues, but I lost a lot of heat in the sparges compared to my old trusty 5g cooler. Very simply, when I added the sparge water, a lot of the heat went to heating up the cooler instead of the grains. I also lost a lot in efficiency. This would partly be because of the low sparge temperature, but I suspect I was getting some channeling with the fly sparge, caused by the larger diameter, and the reduced grain bed depth. Obviously, I need to get used to the new equipment before I can make a sensible judgment, but I'm going back to the 5g cooler for those brews that fit in it comfortably. Why don't you use the 5g cooler for the MLT, and the 10g as a HLT when doing 5g brews? That way you would get the benefit of the extra volume when necessary, and not have any potential problems when brewing smaller batches.
One thing I did like about the 10g size, was that it was much easier to batch sparge with all the extra space in there, but I screwed up on the volumes as well as the temperature when I did this, and my efficiency really sucked.

-a.

I was planning on turning the 5g cooler into an electric HLT.

Like with any cooler, you have to preheat it or calculate for the thermal mass, 5gal or 10gal.

I use a round Rubbermaid 10gal for all my 5gal batches. I've brewed simple pale ales and Belgian quads in it. Works fine. It wouldn't be fine if I were doing 10gal batches (unless I was dong a clone of Michelob 64 )

So does my 5gal round Rubbermaid HLT. No problems fly sparging.

Brewing Clamper said:

I was planning on turning the 5g cooler into an electric HLT.

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Well, that's a pretty good reason.

faber said:

Like with any cooler, you have to preheat it or calculate for the thermal mass, 5gal or 10gal.

I use a round Rubbermaid 10gal for all my 5gal batches. I've brewed simple pale ales and Belgian quads in it. Works fine. It wouldn't be fine if I were doing 10gal batches (unless I was dong a clone of Michelob 64 )

So does my 5gal round Rubbermaid HLT. No problems fly sparging.

Click to expand...

I agree, and that's where my problem is.

I preheat it before doughing in, so if I tell Promash that it has zero thermal mass, it calculates my strike water temperature accurately.
When doing the mash out in the 5g cooler (which is usually about 3/4 full), the Promash strike water calculations are pretty accurate as the entire cooler is already up to 150 +. With the 10g cooler, it is only 3/8 full. Again the strike water calculations are good, but the mash out calculations are now way off because the thermal mass of the more than 1/2 empty cooler is so much greater (especially as the top half of the cooler is at room temperature).

-a.

I have always used a 10 gallon Gott cooler, and I've yet to make a 10 gallon batch! I batch sparge, and I'm thrilled with my MLT. I've never lost temps and just use the regular lid with no issues.

Don't get me wrong. I'm not saying there is anything wrong with the cooler (except for possible channeling problems when fly sparging with a small grain bill), or that it doesn't work. All I'm saying is that is different than a 5g cooler, and that a brewer switching from one to the other will need to make some changes to accommodate those differences if you want to keep the same efficiency.

-a.