False Bottom Advice

[lucianthorr]

Hey everybody. I know there's already a ton of threads about false bottoms and reading through them has already helped me form an opinion but I figured I'd throw it out there anyway.

I've got a rather large (~25gallon) homebrew setup but I generally brew 5 gallon batches. I think because of that, my efficiency over the years has been pretty unpredictable and also, sort of lower than other people with similar setups.
I'm starting to think it's because there's 2.5 gallons of volume below my false bottom and no dip tube to pull from the bottom.
So, I've decided I want a new false bottom...
My current false bottom is 18.75" so I think the best I could do is maybe get one of those Titan 17" domed false bottoms and hope that the weight of the grain will hold down the false bottom.
Do you think that sounds reasonable? Or could mixing out the dough balls and other movements screw up that idealistic theory?
What would you all recommend? I haven't seen anywhere that does custom false bottoms that aren't essentially what I already have where they sit over the output valve.

Thanks.

 

[day_trippr]

What does this existing FB actually look like? Does it have legs?
Seems like the easiest fix is to install a dip tube then shorten the ride height of the FB...

Cheers!

 

[lucianthorr]

That is maybe a better idea. Would you just drill a hole through the FB for the dip tube?
I'm not sure I have the tools to cut the legs these false bottoms though.

https://www.morebeer.com/products/false-bottom-8-gal-heavy-duty-kettle.html

 

[day_trippr]

Hmm....Yeah, shortening those risers without removing could be daunting.

They look thick, too. Like 14 gauge. My bending brake can't even handle bending that.

If you know a welder, the spot welds can be drilled out and filled; new, shorter legs can be attached; and a hole for a dip tube can be cut. You'd have to decide on the specific dip tube so you can locate the pass-through for it, but the rest shouldn't be difficult for someone equipped to fabricate with SS.

That would be the surest way to cut down the rather extreme non-recoverable dead space - which frankly would make me sad...

Cheers!

 

[RPh_Guy]

I'm starting to think it's because there's 2.5 gallons of volume below my false bottom and no dip tube to pull from the bottom.

How are you draining wort from the mash tun?
Have you measured how much wort is left in the mash tun after lautering?

If you have a drain that sits under the false bottom, all you need to do is add a pick up tube to it.

 

[lucianthorr]

It's one of those morebeer tippy-dump setups, so I can tip it over during the drain but there's still at least a gallon left over.
Do you think a simple dip tube is all I need? My gut says that the excess water needed to fill that deadspace is diluting the mash and sparge water but I really don't have any proof.

 

[RPh_Guy]

Do you think a simple dip tube is all I need?

Yes, if the drain is under the false bottom.

For example I use this in my kettle:
https://www.brewhardware.com/ProductDetails.asp?ProductCode=Diptube_Edge

 

[Bobby_M]

Adding a diptube will reduce your actual deadspace, that is wort that cannot be drained, but if you fly sparge that deadspace is not that big of a problem (like it would be if batch sparging).
The problems you are concurrently having right now.

1. With no pickup tube attached to the drain, the wort during a fly sparge is going to channel in a funnel shape from the round surface of the mash down to the drain opening, missing a lot of sugar on the lower end of the grainbed furthest away from the drain.

A fix for this particular problem is just adding a pickup tube, but you will reduce channeling most by having the pickup tube to near the center of the kettle diameter. It will encourage sparge to drop straight down the grainbed. Efficiency gains with this are going to be somewhat limited due to how squat your grainbed is and how much mixing can occur in the large liquid space below the FB.

2. As you suggested, the height of the false bottom forces you into a collectively more dilute mash than would be necessary if the false bottom was only 1/2" above the bottom of the kettle. In the case of mash performance, slow recirculation will compensate for this. However, the main efficiency hit is just having less sparge volume opportunity. That is, you're closer to no sparge brewing when most of your preboil volume is already available in the mash.


You can reconfigure the false bottom by angle grinding the legs off completely, layout out an array of say 1/2" NPT half couplings on the bottom of the kettle and then resting the FB on those. However, you'd then need to drill a hole a little off center and install a bulkhead that has a compression fitting for a pickup tube that would extend to that hole.

 

[lucianthorr]

Thanks Bobby for the thorough answer. I never really thought about the efficiency hit that I'm probably taking due to the small amount of sparge water that I'm able to use. There have been times I've tried to make an incredibly small amount of water last 45 minutes because I hear sparging for 45-60 minutes is ideal.
I've reached out to a local metal shop to see if they'll cut those legs down and drill a hole for me. Hoping to get it done before my next brew day.

Do you have a reference for what you mean by an off-center hole and a bulkhead with a compression fitting? And where I could find a pickup tube that's ~9" long horizontally? I was planning on just buying a standard pickup tube off brewhardware.com but I'm totally up for doing things right if I can manage to get all the parts together.

 

[Bobby_M]

If you put the hole in the exact center of the false bottom, it's very difficult to fit the diptube vertical part into that hole and also get it into the compression fitting. If you drill the hole say 3/8" off center, you rotate the false bottom in place so the hose is furthest away from the compression bulkhead, drop the diptube into the hole, then rotate the false bottom while feeding the diptube into the compression fitting. I hope that makes sense.

 

[lucianthorr]

100% Thanks again