Help with Blichmann false bottom / Stuck recirculation / air in line

[kickz28]

Hi,

I just replaced my MLT with a different one cause I wanted to use my old MLT as my BK.

Anyway, I have a Bayou 10 gallon kettle with a lip near the bottom for the false bottom to rest on. The dip tube is a dip tube I made with copper tubing. It's attached to the kettle with a camlock.

The false bottom fits very tight in the kettle. There is about 2.5 gallons of space under the false bottom.

I tried it for the first time today, and it's not working very well. I recirculate my mash, and it would not recirculate at all, nothing was coming out of the kettle. I had to empty out the MLT and try again. Now it's working but there is a lot of air in the silicone tubing coming out of the MLT going into the pump.

Even with just water and no grains, when I pour water in the kettle, the water kind of stays on top of the false bottom and flows through really slowly. It's weird, not sure why the water doesn't just go right through the false bottom.

Anyone have any tips or any reason this is happening? Thanks!

 

[jekeane]

Do you have a sight glass with an open top? If so seal the top so no air can leak. If you don't inspect your dip tube connections for air leaks.

Air leaks are a possible cause for this problem. Also Just because something is water tight doesn't mean it's airtight.

 

[kickz28]

I don't have a sight glass on the MLT, but I did notice a very small leak between my bulkhead and ball valve for the MLT output. I can see how this would cause air in the tube when trying to recirculate, but could it also cause a stuck recirculation? When I dump water (no grain yet) in the MLT, it takes a long time to go through the false bottom, it's really weird.

My grain bill or my batch was 100% malt, and I crushed it fairly loose with a 0.045" gap.

 

[jekeane]

I believe that when you have an air leak it will break the siphon effect to the dip tube causing a stuck mash and even stuck water.

I have in the past had pump issues related to my dip tube leaking that were solved by adding more teflon tape. As soon as you notice bubbles Use a ball valve on the output side to shut off or reduce the pump flow dramatically until the air pockets fill back up and this may stop it from happening. This method requires a good bit of babysitting though so you'll want to source out the issue.

 

[MaryB]

2.5 gallons under the false bottom??? I would start rethinking things right there...

But any air leak is going to stop the siphon effect...

 

[kickz28]

2.5 gallons under the false bottom??? I would start rethinking things right there...

But any air leak is going to stop the siphon effect...

Why, what's wrong with 2.5 gallons under the FB? This is my kettle:

Other than the trouble I had recirculating at first, it worked out fine. I used more strike water and less sparge, but my efficiency was just fine at about 78% (into the fermenter)

So the siphon effect is desirable?

Thanks!

 

[IslandLizard]

[...] Even with just water and no grains, when I pour water in the kettle, the water kind of stays on top of the false bottom and flows through really slowly. It's weird, not sure why the water doesn't just go right through the false bottom. [...]

That IS weird!
I guess that huge 2.5 gallon air cushion under the FB is giving enough counter pressure to keep the water (and wort!) from flowing through. The very tight fit on the indented rim doesn't help the cause either. Is this a standard FB with 3/32" holes on 5/32" centers?

 

[kickz28]

That IS weird!
I guess that huge 2.5 gallon air cushion under the FB is giving enough counter pressure to keep the water (and wort!) from flowing through. The very tight fit on the indented rim doesn't help the cause either. Is this a standard FB with 3/32" holes on 5/32" centers?

It's a Blichmann false bottom, like this:

 

[day_trippr]

Is someone really suggesting that water can't pass through that false bottom - because there is air under it?

 

[kickz28]

Is someone really suggesting that water can't pass through that false bottom - because there is air under it?

It doesn't stop water from passing through, it's just way slower than expected, and I think this is partly what's causing my recirculating problems.

I'll try to take a video this weekend.