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Outside temperature affect on Mash Tun

Hi,

I am new to all-grain and am about to brew up my first batch within the next week or two. I have been doing a ton of research on forums, books and other reading materials and am pretty excited to start my first batch.

My question is about maintaining a mash temp if I am brewing outside in 40º weather.

I plan on doing a single infusion mash in my homemade 10G rubbermaid mash tun. I am also going to warm up the cooler first, with very hot water for 10-20 minutes before adding my strike water and grain.

How many degrees should I plan on losing per hour while mashing in the cold weather? Is there anything you guys would recommend I do to maintain a consistent temp?

Thank you!!

I brewed two weeks ago when it was 40F & raining. My mash temp went from 153F to 151F in 90 minutes with the mash tun just sitting in my garage on a folding table. I would think you will be fine not doing much of anything. You could wrap the cooler in a sleeping bag if you are real worried though.

In a cooler you should be just fine.

I brewed a few weeks ago - 8*C. I use a stainless kettle to mash. Draped a sleeping bag over for 1 hour mash time. Did not really lose any temp in that time.

I doubt you would even need the sleeping bag, but as pointed out by GeerBoggles, you could always use one if you are worried. Certainly can’t hurt it none.

Just keep it out of the wind and you will hold temp well with a cooler, but I have wrapped it in a blanket when it is extremely cold…but don’t sweat it, you’ll be fine. Hit your mash temp and keep it closed for the whole mash time, because you lose heat opening it up.

You can also use some 1 1/2" blue foam insulation. The closed cell, rigid kind and cut it to fit inside your cooler. Then press it down just above your wort and it will help maintain the heat.

BTW - This product comes in 4’ X 8’ sheets. Ask your local building supply shop if they have any broken ones around. You will probably get what you need free.

When it is <40f I usually add 10-12f to my initial strike temp for my 10 gallon “gott” style cooler.
It is either spot on if really cold or else I stir down a few and then mash in. If under 32F, like -5 ADD 15f.

I almost always cover my MT with a couple of blankets. I’ve noticed that when I remove them after an hour or so, they are quite warm so obviously there is heat coming off the cooler. It does help to stabilize the temperature without a bunch of fancy stuff. :cheers:

[quote=“ITsPossible”]When it is <40f I usually add 10-12f to my initial strike temp for my 10 gallon “gott” style cooler.
It is either spot on if really cold or else I stir down a few and then mash in. If under 32F, like -5 ADD 15f.[/quote]

I haven’t come up with final numbers yet, but due to seasonal variation in strike temps I’ve noticed lately, I’m going to do something similar from now on.

I haven’t noticed as much variation in the temperature drop as I have in strike temps.

We also need to remember that the volume of the mash has something to do with temperature changes, as well. I dropped about 12 degrees over an hour with a BIAB batch in a brew pot indoors because it was only a gallon and a half in the mash for an eventual 2.5 gallon batch. BTW, I got full conversion and raised the temp to make sure I got alpha amylase activity after I discovered the drop (90 minute mash and boils, because it was a bock). YMMV, of course.

:cheers:

In my experience, no reason to worry. After you close the lid, keep it closed and your temp should stay steady within 0-2 degrees of the rest temp that is reached–depending on the volume inside the cooler. More volume = steadier temp.

Not that this will help when using a cooler to mash, but if mashing in a pot (BIAB) outside, I use this.


http://s1093.photobucket.com/user/dobe12/media/photo.jpg.html

I can hold temps within a few degrees for 60min.

put the cooler inside then drag it out to where you are brewing when you are ready to fill the boiler

I have noticed a few posting this advice, as you also live in MN I would assume you do this in practice?

I by necessity have to drag everything including the grain out to the garage the day of brewing no matter the temps. So my equipment starts at room temp. But if your brewing at <32f I would suggest adding 15f to the strike temp required depending on your actual grain temp when mashing in. And if not spot on you will be a few degrees + and can stir down. In the cases I forced myself to brew under 0f, 15f was the magic # otherwise as stated 10-12 is appropriate until your closer to room temp then you can use 6-8f on a regular. I wouldn’t even want to speculate on a guess for preheat if your equipment was actually at 10 below. :mrgreen:

Brewing outside in 40 F?!!! You’ve got to be kidding!

Buy a compass. Get in your car. Head south!

Or, experiment with the same volume of water you’ll be using for your actual brew. Check your temps and see what changes you get over the intended mash time. Then, since your MT will be pre-heated, try it again to see what pre-heating does for you.

I switched to electric because I couldn’t stand to brew outside in 50 F weather.

I have noticed a few posting this advice, as you also live in MN I would assume you do this in practice?

I by necessity have to drag everything including the grain out to the garage the day of brewing no matter the temps. So my equipment starts at room temp. But if your brewing at <32f I would suggest adding 15f to the strike temp required depending on your actual grain temp when mashing in. And if not spot on you will be a few degrees + and can stir down. In the cases I forced myself to brew under 0f, 15f was the magic # otherwise as stated 10-12 is appropriate until your closer to room temp then you can use 6-8f on a regular. I wouldn’t even want to speculate on a guess for preheat if your equipment was actually at 10 below. :mrgreen: [/quote]
That’s why i just throw my cooler inside the garage door. Easy. Warm. Etc…

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