BIAB temperature control

I've been doing partial mashes with BIAB recently. The biggest problem I have is with temperature control. I'll get the water to the target temperature (adjusted for amount and temperature of grain) and everything will be fine but I get such a huge temperature variation between the top and the bottom of the wort. For example, if I'm aiming for 152, I'll get as low as 148 at the top and nearly 160 at the bottom. And if I'm mashing for a long time (more than 30 min), I have to add heat which adds to the discrepancy.

My solution so far has been to continually stir the wort in order to try and keep the temperature somewhat consistent. I'm afraid if I just cover the pot and let it sit without adding any heat it will just cool off too much over time (I did a 90 min mash yesterday).

Is there a better way I can control the temperature short of moving to a more traditional mashing technique?

1. Insulate pot, reflectix, blanket, water heater wrap, sleeping bag ?
Careful adding heat with flammable wraps

2. Recirculation with a pump - this will take the hotter wort and dump it back on top.

3. Some kind of stir device, manual or motorized with lid on to keep heat in.

The Aussies recommend a blanket wrap for simple and cheap. You also need to keep the lid on as much as possible stop peaking in. Make sure you have no dough balls when mashing in then cover and leave alone no need to stir anymore.

I stir really well when I mash in, then cover the kettle and throw a wool army blanket over it, and leave it. After mash time, I turn the burner back on, do a mash out to 170F, stirring a few times during the mash out. Works for me.

I just read that you can warm an oven, cover the pot and put it in there. I'm going to try and do that next time.

I don't do a mash out. Is that necessary if I remove the grain bag and dip it in 170 degrees sparge water when the mash is done? While I do that, I begin to heat the wort for the boil. Is there any reason to heat the wort first before removing the grain bag for spargins?

gio said:

I just read that you can warm an oven, cover the pot and put it in there. I'm going to try and do that next time.

I don't do a mash out. Is that necessary if I remove the grain bag and dip it in 170 degrees sparge water when the mash is done? While I do that, I begin to heat the wort for the boil. Is there any reason to heat the wort first before removing the grain bag for spargins?

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Either way is fine. The oven idea is cool but my oven wont hold my keggle.

Since you're doing partial mashes, I'm guessing it's on a stove top with a bag, pot, and nothing fancy like a false bottom? I have a keggle + false bottom setup that seems to buffer temperature changes, but it might not work for you.

why not build a mash tun? it's like cheap! i mean seriously.

I do my partial mashes in a 5 gallon beverage cooler from WalMart. Cost about $26. Works great, holds the temperature.

Grind or crush you grains very fine since using brew in a bag eliminates the stuck sparge that you otherwise get from too fine of a crush. Bring your water to strike temperature and stir well while slowly adding grain to avoid the temperature difference in the mash and then just put the cover on and forget it. If the air temp isn't too low the conversion will occur quite quickly due to the fine grind or crush and the temperature won't change enough to worry about. If it's cold, wrap your mash tun (or pot or kettle) with a towel or jacket or sleeping bag. Don't open the lid to check the temperature as this is where you lose the most heat.

^^^ What he said ^^^

I'm planning on doing my next BIAB by mashing in at 165ish at around 7.5-8 gallons. I have a 20+ degree sleeping bag I'm going to put over the pot, and hopefully can zip up. I usually brew in my garage with the door open, but for the mash I think I'll close it up to prevent circulation of the air.

I just wrap my pot in old skiing jacket when mash BIAB for 90 min, usually do not lose a single degree without applying any heat and I open the lid to give a good swirl every 20 min or so. I think the key to holding mash temperature in BIAB is little headroom and insulated pot.

^^^^^Great now the real debate starts columbia vs north face which insulates your mash better^^^

mtbiker278 said:

^^^ What he said ^^^

I'm planning on doing my next BIAB by mashing in at 165ish at around 7.5-8 gallons. I have a 20+ degree sleeping bag I'm going to put over the pot, and hopefully can zip up. I usually brew in my garage with the door open, but for the mash I think I'll close it up to prevent circulation of the air.

Click to expand...

I hope you got the mash in temperature by calculating or using a calculator program because it seems a little high in my limited experience. I mash in at about 160 for my setup to get a 152 or 153 mash. It depends a lot on how much grain and the grain temperature though so I may be way off for your setup.

I just threw out a number. I'll be using a calculator next time around. I'm thinking since I brew in a cold garage the grains will be below the typical 70F degrees, plus extra heat loss during the mashing in and stirring.