First mash with new cooler conversion have problem.

I did the first mash in my new 62qt coleman extreme converted cooler yesterday. I actually did two mashes but the first gave me problems.

According to the AHS sheets I got with my kit I warmed up the water to 170*. (20* warmer than their quoted mash temp) I dumped in the appropriate amount of water but the temp only came down to 165*. I added a whole gallon of room temp water and managed to get the temps down to 160*. I let the cooler sit for an hour while I went and picked up my hops (forgot them at home) and when I came back 60 minutes later the mash was at 152*. I then stirred and let set another 20 minutes at which time the temperature was at 150*. The first batch target OG was 1.050 and I got 1.052. I believe the difference in OG was because of the extra 20 minutes of mash.

Second batch I didn't warm the water as much and got an initial mash temp of 155* and after an hour it was still nearly at the same temperature. This batch the target OG was 1.054 and I only got 1.050. I'm assuming the OG was off a little because I left some wort in the pot with the trub as there was a lot. I figure maybe a few cups and I made up for the missing amount with purified water.


Here's the big question: Did I screw up the mash by having the water at the temps they were, or were my temps close enough to still get the correct conversion? I think I have the temp problem solved and will heat my water to no more than 165 on first batch next time and 160 on any additional batches.

You are in range for conversion, no worries.

Your heating problems arise with heat absorbsion by the cooler initially.

The beer should come out just fine, but for more control in the future, do what I do:

Beersmith gives me a strike water temp with no correction for the cooler, so that if you combined that water with room temp grain the mixture will be at my mash temp in a perfect world. (nothing else around to draw heat)

I heat the strike water 10 degrees or so hotter than it needs to be, then add it to the mash tun by itself. I give it 5 minutes to heat up the cooler, then take a temp. When the water in the cooler gets down to the strike water temp I dough in. It adds a few minutes to the brew but I like doing it that way. Sometimes this comes out 2 degrees high or so, in which case I just leave the lid off for a few minutes and stir.

Me too Coastarine.

Coastarine, great idea. I put the grains in first then dumped the water on top. Adding the water first allows you to possibly drain off a quart or two and even replace with cooler water to get the ideal temps if you are off a bit. I have also seen a few people toss blankets over the top of their cooler to keep temps better. I may try that next batch. I did notice I could feal some heat coming around where the lid seals, and while it was minimal, it could potentially be avoided. I've also read someone talk about adding a bunch of ping pong balls to form an insulation barrier.

If you want to get the temperature down quick throw in a few (or more) ice cubes and stir.

With those OGs being as close as they are to the target OG, it sounds like you got great conversion. Sounds like you are doing it right to me.

MikeInCtown said:

I've also read someone talk about adding a bunch of ping pong balls to form an insulation barrier.

Click to expand...

Do you know anything more about that? I'm curious.

I think the brass fittings are where a lot of my heat loss occurs. I'll use my new usb temp probe toy to do some experiments with and without blankets.

I can't remember what conversation it was in, but someone mentioned in the large coolers to use ping pong balls. They apparently use them in manufacturing operations where you have large tanks of warm water and chemicals to slow the evaporation process. I think someone mentioned that one of the grainger/MSC/McMaster places carried them. I'll have to try and see what I can find. I do know that the brass spigot was hot to the touch. I may take a piece of 3/4" pipe insulating foam and slide it over the nozzle just for the mash next time and see how it goes.