Need help with mash tun!!!

[Sreidy12]

Hello all,
I purchased an Igloo Marine 48 qt. cooler a couple of days ago to convert into a mash tun. I completed it today and decided to give it a whirl. I heated up some water and placed it in the cooler, shut the lid for a few minutes to preheat it, took the temp, let it go for an hour, checked again, and woe to me it had dropped 6 degrees. I'm really hoping that adding the grist will change its thermal mass to retain heat better but don't want to waste grain proving my hypothesis. Anybody have any ideas?

 

[halite]

I'm really hoping that adding the grist will change its thermal mass to retain heat better but don't want to waste grain proving my hypothesis

I had the same result when I first tested my mash tun. The addition of grain makes all the difference. When I tested mine with just water it dropped 5-6c, when grist was added, it only lost 1c over the course of 60 minutes. Don't worry it will work fine when you do your mash.

 

[masonsjax]

Be sure to preheat the tun before adding grain. The water loses a few degrees to a cold tun. I like to add my strike water about 5 degrees hot and let it sit for 5 mins. Then I stir til its down to strike temps and add the grain. Works great.

 

[Homercidal]

The more grain and water you have in there, the less it will drop.

Also, if your lid is not insulated (most are hollow), you can drill holes in it and use some spray caulk to fill it.

 

[IrregularPulse]

+1 to MasonJax
You have to account for SOME loss when adding water to a cold mash tun, it has to equalize it's temp between the water and mashtun. Then you'll have another drop when you add your room temp grain.
These numebrs can be easily dealt with with a program like Beersmith. Just enter your grain temp and mashtun temp and desired mash temp and it will tell you what temp you need to add to compensate for both losses. I just add 180 water to my cooler, then let it drop to Beersmith's strike temp based on current grain temp.

 

[ReverseApacheMaster]

It may help to add additional insulation by wrapping it in a blanket, setting it in front of window in front of the sun, etc.

 

[Sreidy12]

Thanks for the help everyone!

 

[Scut_Monkey]

Be sure to preheat the tun before adding grain. The water loses a few degrees to a cold tun. I like to add my strike water about 5 degrees hot and let it sit for 5 mins. Then I stir til its down to strike temps and add the grain. Works great.

+1 to MasonJax
You have to account for SOME loss when adding water to a cold mash tun, it has to equalize it's temp between the water and mashtun. Then you'll have another drop when you add your room temp grain.
These numebrs can be easily dealt with with a program like Beersmith. Just enter your grain temp and mashtun temp and desired mash temp and it will tell you what temp you need to add to compensate for both losses. I just add 180 water to my cooler, then let it drop to Beersmith's strike temp based on current grain temp.

He did state that he preheated the tun. I'm assuming the 5-6 degree temp loss was after it was preheated. I found that spraying spray foam within the lid helped a lot as well as using a smaller cooler with less empty head space.