My mash temperatures are out of control

[SMOKEU]

I'm new to BIAB having done only 2 brews. I have a 50L pot with a stainless basket and a bag inside the basket. I tried making a 23L (final fermenter volume) batch with 25L of strike water, but the mash was extremely thick so I added about 8L of water to thin it out thinking I could do a no sparge and add some DME to increase the OG.

I then added heat due to the extra water, stirring almost the whole time while the heat was on. I put the lid on after checking the temperature was at 65C/150F and turned off the burner, but after coming back 15 minutes it was at 82C/180F! Stirring it a lot didn't change the temperature at all. I moved the thermometer around a little to see if the reading changed but it didn't.

I threw it out. This is the second time this has happened to me. I don't know if I should just try no-sparge mashes adding extra grain to compensate for the low efficiency or what.

 

[eanema]

It sou.ds to me like you are having two problems. First you are not correctly calculating your initial strike volume and the second problem is controlling the temperature.

With regards to the volume you should use a calculator to make a good guess at all the various water volumes along the way. For example, I recently did a 21L porter with these volumes:

Into Fermenter 21.0 [L]
Post-boil Wort 27.0 [L]
Pre-boil Wort 31.1 [L]
Total Mash Volume 36.4 [L]
Strike Temp 71.7 [*C]
Total Water Needed 32.8 [L]

I would recommend that you use a calculator for the first guess then calculate your trub loss, your grain absorption, your boil off rate, etc. and then plug in your measured values into the calculator when you do your next batch.

I made a spreadsheet to calculate these volumes but you can more easily use an online calculator website such as: http://www.biabcalculator.com/


Your second issue with temperature can be controlled in a few ways. First, if you have the correct strike water volume at the correct temperature you won't have to add as much heat to keep temperature once the grains are in. But in the case you described, where you are trying to step the water temperature up a significant amount, I suspect what happened is that the bottom space below your basket was warmer than you expected, plus the burner probably had some residual heat.

What is do to control the temperature is something not everyone's wives would allow. Before I start the brew process I open up the stove and install a solid state relay in series with the heating element on the stove. I then use a $20 eBay temperature controller to control the temp of the mash. If you put the temp prob right into the dead space below your basket you can get fairly good control of the mash temp.

That method is not for everyone. Fact is you are overshooting your mash temp. Best line of defence is to raise temp slowly and stir often. And make sure you mix the water in the dead space the best you can.


*Edit
I just read your post again and realized you were planning to sparge... Clearly I do a full volume BIAB

 

[wilserbrewer]

You have wort outside the basket that when heated does not efficiently transfer heat to the mash within the basket. In order to correct this you can recirculate with a pump.

You can also not use the basket and mash full volume without the basket using just a bag.

 

[SMOKEU]

I have tried using a calculator to figure out my water volumes, but I find that the mash is so thick it appears to look more like a solid mass than a liquid and I think the water doesn't effectively mix with the grains in that case.

 

[LittleRiver]

...stainless basket and a bag inside the basket.

The basket causes a significant amount of your water to be segregated from your grains. Use just the bag, without the basket.

...I don't know if I should just try no-sparge mashes adding extra grain to compensate for the low efficiency or what.

If you have your own mill, and can grind your grains very fine (~.025in mill gap) you should be able to do no sparge without any efficiency problems. I routinely exceed recipe targets this way -- no added grain or DME, no sparge.

I have tried using a calculator to figure out my water volumes, but I find that the mash is so thick it appears to look more like a solid mass than a liquid...

Something is not right with your calculations and/or with your rig (perhaps the basket is separating a large amount of water from your grains?).

 

[doug293cz]

I have tried using a calculator to figure out my water volumes, but I find that the mash is so thick it appears to look more like a solid mass than a liquid and I think the water doesn't effectively mix with the grains in that case.

Any water/wort outside the basket does nothing to help thin out the mash. Going full volume mash, no-sparge will give you a larger mash volume, and may give you a thin enough mash to be workable. Depends on just what the volume outside of the basket is. Or, you could just skip the basket and go with a bag only. Lots of us do.

Brew on

 

[ScrewyBrewer]

I've switched over to using a Wilser bag and a false bottom. I quit using a stainless basket and will never go back to using it. The bag spreads out to the full width and depth of the kettle now, letting all of the grain come into contact with all of the mash water.