E-BIAB recirculation and conversion

[daveMN]

Hi all, I'm scratching my head with my recirculating E-BIAB not getting good conversion. I brew 5 gal batches in a 15 gal kettle. The element is 4500 watt, 90 degrees from the outlet, controlled with a Auber DSPR300 and the temp probe is 180 deg from the outlet. I have an inverted cooler lid as a mash cap with loc-line with a March pump to recirculate. I have a Wilser bag with a Brewhardware false bottom.
I'm getting starch haze and slow conversion from my single step mashes and thin beers doing step mashes. Idiot me, I didn't check the mash temp at the top of the tun because the temp probe is calibrated. I finally checked the temp, and the mash was about 7 degrees below the temp probe. I have been recirculating slowly, which I think plays into this. Trying to figure out what to do, I'm thinking about one or more of the following:
- increase flow through the pump.
- move the temp probe nearer to the outlet. Not sure that will fix the temperature stratification.
- add a center pickup for recirculation. The thought being that I'm getting channeling/lack of mixing.
Add a locline sparge ring
- something else I'm not thinking about? I thought about adding a RIMS/HERMS but that doesn't fix any temp gradient in the mash tun.
Thoughts? Cheers! :beer:

 

[doug293cz]

I would run the recirc as fast as your grain bed will allow. You may have to start slow and then increase as the mash progresses. The locline sparge ring sounds like a good idea. I'd leave the control temp sensor near the element, so as to be able to prevent overheating the wort.

You might want to think about adding a second temp sensor that can be moved around in the grain bed to monitor actual mash temps. Then you can determine an accurate offset for your temperature controller in order to get the mash temp where you want it.

Brew on

 

[ScrewyBrewer]

The eBIAB I use has the temperature sensor mounted at the top of the kettle, where the wort enters the lid. It measures the wort temperature at the top of the grain bed, eventually with enough flow, the entire grain bed will reach set point temperature.

I run a Chugger pump wide open and the wort passes through a 'spray nozzle' to produce a shower head like spray pattern. I never measured the GPM output, but the flow rate is enough to create a wide spray pattern on top of the grain bed.

The heating element is an ultra-high density 4500 watt, which according to the manufacturer of the system, is incapable of scorching wort it comes in contact with. The top spray nozzle is centered on the kettle and it uses a side port return mounted near the kettle bottom, about the same height from the bottom as the heating element.

 

[daveMN]

I would run the recirc as fast as your grain bed will allow. You may have to start slow and then increase as the mash progresses. The locline sparge ring sounds like a good idea. I'd leave the control temp sensor near the element, so as to be able to prevent overheating the wort.

You might want to think about adding a second temp sensor that can be moved around in the grain bed to monitor actual mash temps. Then you can determine an accurate offset for your temperature controller in order to get the mash temp where you want it.

Brew on

I'll give a full flow recirc a try and report back. That's definitely the cheapest fix. I like the idea of adding a second temp probe inline or near the top of the mash. Here's what it looks like now. Thanks for the feedback doug and screwyBrewer! :beer:

View attachment 1498794636459.jpg

 

[tomofdarkness]

Did you try stirring?

 

[daveMN]

Did you try stirring?

I did on the last brew day, but with the recirculation, in theory, I shouldn't have to.

 

[tomofdarkness]

I did on the last brew day, but with the recirculation, in theory, I shouldn't have to.

If you have the problem without stirring, but stirring solves it, then your problem is that the grain bed is getting compacted and forming channels. No amount of extra flow is going to solve that problem.

 

[daveMN]

If you have the problem without stirring, but stirring solves it, then your problem is that the grain bed is getting compacted and forming channels. No amount of extra flow is going to solve that problem.

Stirring didn't solve it. I was recirculating pretty slowly up until now.

 

[pocketmon]

Stirring didn't solve it. I was recirculating pretty slowly up until now.

IMO, stirring the mash should work better than pump driven recirculation.

I am using Grainfather and have used two sensors to monitor the temperature above and under the mash.

The heat is applied the the wort at the bottom (under the mash), and the heated wort drains SLOWLY through the grain bed once the grain bed becomes compact. That causes the difference of temperature.

Stirring the mash surely helps. I have tried. or, YMMV.

The other way to solve this issue might be using the same strategy as Braumeister, pumping the wort from bottom to up, which will prevent forming of grain bed.

 

[daveMN]

Following up on this, I brewed last night with full recirculation after slowly increasing flow over a minute or two. Temps at the top of the MT were within a degree or two of the bottom. And, the wort was crystal clear and my efficiency went up about 10%, which was an unexpected benefit.
I did notice the temps at the top of the MT seemed to increase steadily degrees over the course of the mash, above the set point. I can post data later.

 

[applescrap]

Why recirculate? Just my opinion.

 

[daveMN]

I recirculate for step mashing and to stop wrapping up the MT with blankets to maintain mash temps.