cooler losing temp

so i am about to make a mash tun out of this cooler i have here. just as a test i put in my hot tap water about half way up the cooler.

it was 139 *f when i started.

after an hour it was 133*f

is this loss acceptable or should i find a new cooler?

will the grains hold temp better than just plain water?

Did you preheat the cooler? I usually preheat my cooler with 180 degree water and dump it out, or just add hotter strike water and let it cool before adding the grains. Either way works.

If you preheated your cooler, I'd say that the grains will help hold the temperature better but it might not be great. If you didn't preheat, then I recommend preheating it when you brew, and it'll be fine.

I wrap mine in a big sleeping bag once the grains are inside. I might loose two degrees in a 90 min. mash. I've never tested it with just water. But I suspect adding the grains will make a pretty big difference.

the cooler was pretty warm when i started. i cleaned it with the same temp water when i did my test

i have a second cooler i am going to try. if i get better results i'll just use that one

I've seen usually no more than about 4 degrees in 90 mins on my cooler, but again that's w/ the grain bed too, that may help retain heat better than just water.

Did you stir it for a few minutes after adding the water and before taking the initial temperature reading? If the cooler isn't pre-heated, the temperature will sag over the course of a few minutes as everything stabilizes.

Note... this based on experience of exactly 1 AG brew... but it does seem to not be an instantaneous temperature drop after the water goes in.

i am doing a second tesst. i plan on checking this one every half hour for 2 hours

second test different cooler this time.

30 min down 2*f
60 min down 4*f
90 min down 4.5*f

i think i'll go with this one. i am sure the grains will hold heat better than just air and water

Last time I brewed I forgot to heat up the cooler and I lost about 15 degrees F in about 30 min, I basically had to pull some wort off and heat it up again to bring the temp back up. The cooler was probably at about 32 F when I mashed in so thats why the change was so drastic but not preheating the cooler makes a big difference.

Ewalk02 said:

Last time I brewed I forgot to heat up the cooler and I lost about 15 degrees F in about 30 min, I basically had to pull some wort off and heat it up again to bring the temp back up. The cooler was probably at about 32 F when I mashed in so thats why the change was so drastic but not preheating the cooler makes a big difference.

Click to expand...

Just FYI..

I think it is better to pull mostly grain from the mash, like a thick porridge, and heat that. A decoction basically. Heating thin wort can denature many of your enzymes.

Thanks for the heads up, hopefully I wont be having these problems anymore though. I just bought two more kegs to convert and I think I'll be going all electric with this new rig.