How to prevent big mash temperature drop during a BIAB mashing?

[Miles_1111]

I am doing BIAB and using boiling tun as the mash tun. As the tun does not have the layer to protect the temperature, the mash temperature drop 3 Cel during a 60 mins mash, that is around 1 Cel per 20 mins... I am think to add a layer of somthing on the side of the tun to prevent the drop. Any advices that to add or any other solution? Thanks in advance.

 

[myndflyte]

Big sleeping bag, blankets, anything that has some sort of insulation should do the trick.

 

[Dancy]

I am doing BIAB and using boiling tun as the mash tun. As the tun does not have the layer to protect the temperature, the mash temperature drop 3 Cel during a 60 mins mash, that is around 1 Cel per 20 mins... I am think to add a layer of somthing on the side of the tun to prevent the drop. Any advices that to add or any other solution? Thanks in advance.

Reflectix — available at any large hardware store such as Lowe’s, Home Depot, etc.

 

[RM-MN]

. As the tun does not have the layer to protect the temperature, the mash temperature drop 3 Cel during a 60 mins mash, that is around 1 Cel per 20 mins.

The temperature is only critical during conversion. Since you are doing BIAB the milling of the grain can be much finer than for a conventional tun which leads to a much faster and probably more complete conversion. That means that you don't have to maintain the temperature for the full hour and if your grains are milled very fine your conversion is done before the temperature has dropped even the one degree C. Get a bottle of iodine and test your grain for conversion during the mash period. Check it once every 5 minutes until the iodine stops turning blue which signals that there is still starch to be converted.

No matter what you find about the speed of conversion, do not cut the mash too short as it takes more time to extract the color and especially flavor than it does to convert the starch. I do not recommend a mash of less than 30 minute although my experimentation showed that 20 minutes was sufficient.

 

[Miles_1111]

The temperature is only critical during conversion. Since you are doing BIAB the milling of the grain can be much finer than for a conventional tun which leads to a much faster and probably more complete conversion. That means that you don't have to maintain the temperature for the full hour and if your grains are milled very fine your conversion is done before the temperature has dropped even the one degree C. Get a bottle of iodine and test your grain for conversion during the mash period. Check it once every 5 minutes until the iodine stops turning blue which signals that there is still starch to be converted.

No matter what you find about the speed of conversion, do not cut the mash too short as it takes more time to extract the color and especially flavor than it does to convert the starch. I do not recommend a mash of less than 30 minute although my experimentation showed that 20 minutes was sufficient.

That makes good sense. Thanks. So I guess the 3 C drop in temperature does NOT affect much about the extract of malt color and flavor, right?

By the way, my BIAB mash efficiency is about between 75% to 77%. Is that a problem or does it mean my crush is OK? Cheers.

 

[SilvioJesus]

75% to 77%? That's pretty damn good for BIAB.

 

[Miraculix]

The temperature is only critical during conversion. Since you are doing BIAB the milling of the grain can be much finer than for a conventional tun which leads to a much faster and probably more complete conversion. That means that you don't have to maintain the temperature for the full hour and if your grains are milled very fine your conversion is done before the temperature has dropped even the one degree C. Get a bottle of iodine and test your grain for conversion during the mash period. Check it once every 5 minutes until the iodine stops turning blue which signals that there is still starch to be converted.

No matter what you find about the speed of conversion, do not cut the mash too short as it takes more time to extract the color and especially flavor than it does to convert the starch. I do not recommend a mash of less than 30 minute although my experimentation showed that 20 minutes was sufficient.

There is still starch which is not gelatinised and not yet accessible for the enzymes, which the iodine test won't show. The test is only for the starch that might be in suspension and gelatinised. Not all starches gelatinise as quickly as the other, particle size and other factors play a role. Therefore it makes sense to maintain the same temperature, also in full volume biab situations.

You won't pick these starches up with the iodine test in the liquid, but if you would drain some of the soaked grains and do the test with them, you might be able to see the starch in there.

 

[RM-MN]

75% to 77%? That's pretty damn good for BIAB.

It is pretty good for a no-sparge. Not quite so good if a sparge is incorporated. Not good at all if there is a double sparge. If it truly is for mash efficiency and not brewhouse efficiency that would be pretty low and would indicate a coarse crush. For a fine crush the mash efficiency should be in the 90% or higher range. One never can capture all the sugars from the grain so brewhouse will be lower.

 

[NewJersey]

I'd recommend adding a heating element to the kettle controlled by a pid, add a pump, and recirculate during the whole mash.

 

[enkamania]

I use a sous vide for overnight mashes.

 

[wsmith1625]

I am doing BIAB and using boiling tun as the mash tun. As the tun does not have the layer to protect the temperature, the mash temperature drop 3 Cel during a 60 mins mash, that is around 1 Cel per 20 mins... I am think to add a layer of something on the side of the tun to prevent the drop. Any advices that to add or any other solution? Thanks in advance.

The responses you received so far are all good methods. I'm sure they are using them with success, so it really depends on how technical a solution you want and how much you want to spend. I opted for a simple solution and since it's working, why change it.

As @myndflyte suggested, sleeping bags and blankets work well and you probably have some lying around the house already. If you have a spare pillow, I would throw it on the lid first since that is where the most heat is lost. Then cover everything with a couple blankets or a thick sleeping bag and it should hold temp pretty well. I also secure the blankets around the kettle using a long bungee cord. You could also tie them off with a rope.

 

[SteveH aka shetc]

I use reflectix to wrap the kettle. I usually have a temp drop of about 3-4 degrees over a 90 min mash.

 

[Shaika-Dzari]

I use my oven.
Its lower temperature is 170 so I start it in advance, then 5 mins before the mash I stop it. When my mash is ready, I put the kettle in the oven.
I usually mix the mash every 15 minutes. I check the temp and if it has dropped a bit, I start the oven 30 sec and then put the kettle back.
It works really well and the temp stay quite constant.

 

[slurms]

I keep mine simple, sit my kettle on folded up flannel sheets, wrap it in the other sheet, and a wool blanket on the lid. And then try to tie rope around it all to keep it nice and snug. Lifting the kettle is a pain, but if you've got someone to help, it's a lot easier (assuming you're doing a 5 gallon batch) Though, I will lose 3-4F (like, 1-2C?) in the summer, not looking forward to see what will happen in the winter...

I lost more heat than normal my last brew, so I lifted the 10 gallon kettle (full of water and grain, FULL), back up on the burner, lifted the bag out enough so I "knew" it wasn't in contact with the bottom, and fired her up again. Little did I know that one of the nylon loop at the top of the bag got hot and melted (no more loop) even though it wasn't anywhere close to the flame (I blame heat transfer here...). I would opt to not do that if you have the chance.

@shetc , is that sheet metal wrapped around a propane burner? I imagine so since I see a tank in the background, but I could see it being a fancy induction burner. I've saw people say "use thick tinfoil" to wrap around the base, but the sheet metal is definitely much better.

 

[odie]

I use reflectix and also an internal element and small recirc pump. I've held temps for 10 hours, mashing while at work or overnight.

But all you really need is a wrap of some type for your kettle. Most of the conversion is gonna happen in the first 20-30 minutes anyway. the rest of the time is just finishing up that last bit of starch and or/holding the temps until you get back to start the boil.