Electric BIAB Woes

[samc]

Doing my fourth BIAB on my new single kettle set up. First three brew days were pretty much uneventful but today I ran into a problem. I decided to do a 104F rest to check PH and adjust but my temps overshot to 111F before the grain went in. I had a lot of trouble getting the temps to drop, unplugged the element, tested to make sure it was not getting 120 or 240 to it when the temp was higher than set point and it wasn't. Eventually the temps came down but very slowly. When I got to mash out temps I noticed the wort volume in the kettle getting closer to the top which was unusual so I killed the power and pulled the bag away from the sides of the kettle. It seemed as if the wort was near boiling underneath the bag and a suction had been created. I recovered after a lot of extra work which I will spare you the details.

Any ideas what went on? I am recirculating the wort and that never slowed or stopped so it hadn't created any kind of stuck situation. It was 15 lbs of grain in a 15 gallon kettle with 10 gallons of water so it should have had the room. The crush was finer than I usually do which as far as I know is ok for BIAB.

Not sure if it's an element problem (doubt it) or just a technique issue. Sorry for the tough one!

 

[Brewing Clamper]

I'm a bit confused by your setup, could you explain it in more detail? Are you recirculating throughout the mash?

 

[samc]

Yes, I am using a pump to recirculate. I have a SS false bottom and an Auber 2362 PID with RTD for temp control. The kettle is similar to the MegaPot 15 gallon kettle.

 

[jhollist]

samc,

Where is your temperature probe in your set-up?

I could see there being some problem if it is up above the false bottom.

Cheers,
Jeff

 

[samc]

Temp probe is beneath the FB.

 

[Yooper]

It seems like there was a vacuum created, from the way you're describing it. Not for the temperature issue, but later on.

I have no idea why you'd be 7 degrees over the set point, though.

 

[samc]

Yooper, it was surely a vacuum, when I pulled the bag away from the sides it did mini eruptions. I thought it was going to come exploding out of the kettle, that's why I hit the kill switch (thanks PJ) and stood back to await the lava (wort). What I can't figure out is why and how to prevent it from happening again. My system is pretty accurate when it is filled with grain and temps don't wander much, but when it is just water it overshoots - the odd thing this time was that it didn't cool down very fast, which is unusual.

 

[emjay]

It's the crush. You using the Braumeister system? This is a known issue when using too fine a crush.

 

[samc]

No Braumeister, but a similar home made set up with a bag instead of the malt pipe. What is the solution - how coarse a crush? Or should I just go back to conditioning?

 

[emjay]

No Braumeister, but a similar home made set up with a bag instead of the malt pipe. What is the solution - how coarse a crush? Or should I just go back to conditioning?

It's impossible to say precisely the gap setting that should be used for any particular brew, going coarser and/or conditioning your malt should both help - the same principles that prevent stuck sparges in a 3V system should also prevent a vacuum from forming.

 

[samc]

Thanks - I just did a quick scan of the Yambor thread on Braumeister and saw some posts about that problem. I going to go back to conditioning before spending time/money on more Stainless parts that might not work anyway. And then of course 50 cents of rice hulls might be a solution.

 

[P-J]

Doing my fourth BIAB on my new single kettle set up. First three brew days were pretty much uneventful but today I ran into a problem. I decided to do a 104F rest to check PH and adjust but my temps overshot to 111F before the grain went in.

Sounds like a PID setup problem. Just water, temp set for 104° and it hit 111°. Temp probe under FB which is also where the heating element lives. I'm assuming that you were recirculating during this heat up process. No? If not, that could be a root cause (stratification). If you were recirculating, then either the PID parameters are in question or the temp probe placement is not measuring the actual output temperature but is measuring an eddy current (a low flow part of the water stream - probe possibly placed on the opposite side of the kettle from the output port? That way it would tell the PID that the temp was not quite there and deliver more power.)

Anyway, Sorry for thinking out loud.
P-J

 

[P-J]

Yooper, it was surely a vacuum, when I pulled the bag away from the sides it did mini eruptions. I thought it was going to come exploding out of the kettle, that's why I hit the kill switch (thanks PJ) and stood back to await the lava (wort). What I can't figure out is why and how to prevent it from happening again. My system is pretty accurate when it is filled with grain and temps don't wander much, but when it is just water it overshoots - the odd thing this time was that it didn't cool down very fast, which is unusual.

I'm glad you included the EPO in your setup as events like that makes it well worth having available.
And it's not the time to be searching for the power cord either.

 

[samc]

I'm glad you included the EPO in your setup as events like that makes it well worth having available.
And it's not the time to be searchind for the power cord either.

Yeah, I was thinking I really need to go turn that thing off just in case and I remembered that little yellow button which was within reach. Thanks.

As to the overshoot, since it doesn't happen all the time I am at a loss to figure it. Next brew I am going to set the desired temp cooler than I want and see what happens. The first 3 brew days and the 3 trial water runs had some overshoot but I thought I fixed it. I wonder if the placement of the return hose is crucial to be in the same spot?