BIAB recirc setup - How to connect and remove the false bottom?

[NeoBrew]

I am just taking the leap from BIAB to BIAB with mash re circulation. I am all set to buy the fittings, cam locks, and a false bottom.

I do a bottom heating method with my mash now. It's just a hot plate controlled by an STC 1000. I am planning on adding a false bottom to keep the bag off the bottom and to allow better circulation of the wort to the pump. I have a 10 gallon megapot from northern brewer, which has a 14 1/8" inside diameter.

I'm looking to not spend a fortune on a false bottom, and it looks like the best option for me might be a 12" domed false bottom. I'm open to suggestions if there are better options.

I'm wondering how people usually connect the false bottom to the inside of a weldless valve bulkhead. Mine is currently just a 1/2" NPT nipple. One trick to my setup is that I need to have the ability to pull the false bottom out with the kettle full of hot wort. I plan to attach a wire to the false bottom so I can remove it. Obviously the trick will be to make sure the silicone tube comes with the false bottom. Also, whatever I use to connect to the valve needs to be able to survive the boil.

Any recommendations for the configuration of the false bottom, or a source for an economical false bottom on legs that would avoid my connection problem would be appreciated.

 

[TexasWine]

How about a pizza screen with stainless steel bolts + washers as legs? A lot cheaper and you don't have to worry about connecting anything to it.

Update International PS-14 Aluminum Pizza Screen, 14-Inch https://www.amazon.com/dp/B0029SXJAE/?tag=skimlinks_replacement-20

 

[wilserbrewer]

Or perhaps an appropriate size basket, there's quite a few on eBay. I'm guessing a basket may be less prone to a stuck recirc sparge than a FB ... No direct experience just read it on the web somewhere

A basket is more turn key vs fabbing something idk....just a thought

 

[NeoBrew]

The pizza screen is something I had been considering. I tend to avoid aluminum in my setup, but for the price it seems like a great value compared to all the stainless options. Plus, it's got a very open weave. I know one of the issues with recirc mashes is circulation through the grain bed, the openness would help I think.

I'm not too sure about the basket solution. I would be concerned about giving up the volume in my mash tun. I wonder if the perforations actually produce less surface area than a mesh screen just at the bottom?

Ultimately, a fine mesh basket would be awesome, just not sure I can make that big of a leap right now. Perhaps some day.

 

[Hellosluggo]

Here's a pizza disc + 4" stainless carriage bolts for legs. I use a 135º stainless side pickup tube (not installed in the photo) to allow for whirlpooling. Just pull the bag and false bottom and stir away.

 

[NeoBrew]

That's a pretty well put together set up. It looks sturdy. I ordered an aluminum screen version. It should fit my pot exactly.

Do you have any issues with the bag slumping down around your screen?

 

[NeoBrew]

I had my first successful recirc brew day. I overshot my numbers a bit, but with a Belgian Double I think there is some room in the style to absorb it.

There was a casualty in the process. I went with an aluminum pizza screen. I choose the mesh kind, which was a mistake in my case. During the mash I found that the bag was getting sucked down along the edges. I turned off the pump and clipped the bag up on the edges to hold it. Eventually I fount the right spot to hold it. After the mash I pulled the screen and was surprised to see it had completely collapsed! The screen bent at the bolts and the mesh deformed and pulled out of the edge frame at one point. I'm not sure if I might have started the failure by stirring and bumping the screen, but clearly it wasn't strong enough. I'm amazed at how much power that pump must have been creating in there. I'll have to go back to the drawing board on that one.

Because pulling the bag up off the bottom seemed to work, I am wondering if I can just get away with making a custom back that fits tightly enough that it sits off the bottom of the pot. I might even be able to throw together a SS frame that would hold the bag in place while I mash. I could slip the frame inside the bag while I dough in so the bag doesn't collapse as I stir, then when it comes time to pull the bag I can slip the frame out and proceed as usual.

I might also just cry uncle and buy a regular false bottom. I'm sure that could handle the pressures.

 

[Ozarks Mountain Brewery]

I use a pizza screen like above but made legs with aluminum strips, helps support the heavy grain better

 

[TexasWine]

I had my first successful recirc brew day. I overshot my numbers a bit, but with a Belgian Double I think there is some room in the style to absorb it.

There was a casualty in the process. I went with an aluminum pizza screen. I choose the mesh kind, which was a mistake in my case. During the mash I found that the bag was getting sucked down along the edges. I turned off the pump and clipped the bag up on the edges to hold it. Eventually I fount the right spot to hold it. After the mash I pulled the screen and was surprised to see it had completely collapsed! The screen bent at the bolts and the mesh deformed and pulled out of the edge frame at one point. I'm not sure if I might have started the failure by stirring and bumping the screen, but clearly it wasn't strong enough. I'm amazed at how much power that pump must have been creating in there. I'll have to go back to the drawing board on that one.

Wow! That's surprising. Thanks for the update.

 

[Ozarks Mountain Brewery]

make sure your screen is around 1 inch smaller than the diameter of the pot other wise your bag will drop down the outside and cause uneven recirculation

 

[wilserbrewer]

Or perhaps an appropriate size basket, there's quite a few on eBay.

Let's say a pump can easily put a negative 3 psi on a FB, with over a hundred square inches on a 12" FB, that could exceed 300 lbs of force on a 12" pizza screen and around 450 lbs on a 14" screen, not sure about that.

A basket can also recirc through the side of the basket, providing greater surface area, and perhaps an alternate path with less resistance then through the grain bed.
Good luck.

 

[Hellosluggo]

After the mash I pulled the screen and was surprised to see it had completely collapsed!

I think the main issue here was not having center support, plus the screen offered no rigidity... With the aluminum pizza disk I'm using, you can add as many carriage bolts or "legs" as you think you need to provide rigid support in the center. I've had no problems with the 5-leg disk, and to answer your previous question (sorry I missed that), no problems with the bag slipping down around the disk.

 

[NeoBrew]

Yes, I clearly underestimated the forces at work. Whatever my next step is it needs to have a lot more structural integrity. I'm tempted to just invest in a stainless false bottom.

 

[wilserbrewer]

Lots of variables here, coarse crush may free drain, fine crush can pack like mud.