BIAB bag getting sucked down to false bottom

[Rob2010SS]

You don't want too much space underneath the false bottom assembly, adding a 2nd one increases that space.

I think the issue in your current system is that when the mesh bag is resting upon the false bottom, it's not permeable enough. The much coarser grate of the NorCal false bottom may help alleviate that. Or not, the bag's finer mesh being the restriction.

But reducing the flow rate may simply solve the problem, without resorting to a coarser grate.
Have you measured the actual flow rate?

I have not measured the actual flow rate of the pump. Not even sure how I'd do that, other than a flow meter which I don't have or collecting wort for a measured period of time...

 

[Rob2010SS]

It's all about flow rate. Nothing else. If your pump exceeds the natural flow rate of your set up then you will get stuck. You can't push/pump/suck it through...it has to flow naturally.

Crush, bag mesh and surface area are the 3 things you need to look at. 3 is the number and the number is 3 "Monty Python"

1. Crush: a finer crush slow the natural flow rate. Improved conversion but reduce circulation.
2. Bag mess: smaller micron will slow the flow rate.
3. Surface area: how much of the bag's bottom is exposed, ie not touching AYTHING? Anything the bottom of the bag is touching or resting on will stop the flow. A false bottom blocks the bag any place it touches. The more gaps or open space the FB provides the better the flow. A steamer basket has only a few holes to allow flow and a lot of solid bottom area, so a steamer rack or something holds the bag off a little, providing more exposed surface area to flow.

All three affect flow rate. Match your pump to that flow rate. Either improve any/all of those 3 to match the pump. Or reduce the pump to match the 3 flow limitations. Do both until they are in equilibrium.

Better, have the natural flow rate exceed the pump. I think most pumps people are using are over sized for the need.

Ok, so if I took @yorkeken advice and just swapped my false bottom for that BIAB false bottom, that may actually help as well based on your number 3.

As you can see, there's a lot of surface area on that false bottom where when the bag is in contact, it could block the flow. By giving more room for liquid to flow, may help my issue. That in combination with reducing flow a bit, if need be.

 

[tracer bullet]

I like that grated thing better. It'll do the job and have like 0 restrictions. The one you linked would be better than what you have perhaps, but - why not go for it?

Either way though, you're on the right track. Reduce the amount of stuff impeding the flow.

For the flow rate it's easy, next time you have a pot filled with water connected to your pump, maybe for cleaning or before you get it to strike temp, move it into another one with the pump and 1) count how long (time) it takes to 2) move X (volume) amount of water. 3 gallons in 30 seconds or something like that (which would of course be 6 gallons / minute). The math for flow rate will fall right out of that. It's also probably published, most companies use it for their advertising.

 

[IslandLizard]

I have not measured the actual flow rate of the pump. [...] or collecting wort for a measured period of time...

Yes, it's that simple! Collect the outflowing wort in a pitcher or so for 10 or 20 seconds.

 

[Jayjay1976]

I also BIAB with a @wilserbrewer bag and a false bottom from @Bobby_M at brewhardware.com

Killer combo. I like it better than my true bottom.

 

[Bobby_M]

So I already have a false bottom that I'm using. Is there any issue in using this BIAB false bottom on top of my pre-existing false bottom? The idea is to keep the bag off of my current false bottom and this would be perfect, but want to make sure I'm not missing any negative aspects of doing this.

Yes. A HUGE difference. Picture it like this... once you build up some suction under your false bottom, the bag gets pulled down hard to the false bottom. Now the only place the bag is able to drain is the spaces directly over the cut slots. When you switch to my coarse wire mesh false bottom, you get about 95% open area so you'll drain through almost the entire diameter.

 

[Jayjay1976]

Yes. A HUGE difference. Picture it like this... once you build up some suction under your false bottom, the bag gets pulled down hard to the false bottom. Now the only place the bag is able to drain is the spaces directly over the cut slots. When you switch to my coarse wire mesh false bottom, you get about 95% open area so you'll drain through almost the entire diameter.

^^This is some DEEP TRUTH^^

Ain't no false bottom
Like a BH false bottom
Cuz a BH false bottom is
PERMEABLE.

 

[odie]

Ok, so if I took @yorkeken advice and just swapped my false bottom for that BIAB false bottom, that may actually help as well based on your number 3.

View attachment 747660

As you can see, there's a lot of surface area on that false bottom where when the bag is in contact, it could block the flow. By giving more room for liquid to flow, may help my issue. That in combination with reducing flow a bit, if need be.

You want something that looks like post #23. that FB you have looks like a manhole cover...

 

[odie]

You don't have to measure your flow rate...you just need to observe that the bag is draining faster than the pump is pumping...

watch your sight tube as the pump is running...if the level starts dropping then you know your pump is out running the bag flow.

If you don't have a sight tube, watch the wort level inside the bag...if it's going up then the bag is filling up faster than it can drain.

mark the starting level before running the pump. This is your base line. Once the pump is running it should not change unless you have a "problem" like too much pump or too little flow.

 

[odie]

https://www.amazon.com/gp/product/B06XC8D7HK/ref=ppx_yo_dt_b_asin_title_o02_s00?ie=UTF8&psc=1
this is what I placed inside my steamer basket and directly under my Wilser bag...huge game changer for recirc.

 

[k-daddy]

So I already have a false bottom that I'm using. Is there any issue in using this BIAB false bottom on top of my pre-existing false bottom? The idea is to keep the bag off of my current false bottom and this would be perfect, but want to make sure I'm not missing any negative aspects of doing this.

That would defeat the purpose. Bobby's BIAB FB is designed to replace the FB's intended for un-bagged grains.

 

[Rob2010SS]

https://www.amazon.com/gp/product/B06XC8D7HK/ref=ppx_yo_dt_b_asin_title_o02_s00?ie=UTF8&psc=1
this is what I placed inside my steamer basket and directly under my Wilser bag...huge game changer for recirc.

Thanks for sending that! I have a few options to try out!

 

[mwayne112]

Much better to slowly open the pump valve over the course of ~10 minutes to prevent sealing the grain bed. Disagree a high flow rate is the issue, but rather a high flow rate too quickly. With a rotometer/flowmeter it is easy to consistently increase flow rate at a known rate.

 

[BarryBrews]

If you thoroughly stir the mash grains instead of manipulating the brewbag and the flow is restored then it must be the new brewbag mesh size causing the issue in your setup. All things the same. Recently replaced mine and stayed with the 200 mesh size.

 

[Rob2010SS]

Alright, update on this issue...

I purchased the BIAB false bottom from Brew Hardware, like the one pictured here...

I purchased it without the legs because i was thinking I would do like what is shown in this picture and have my dip tube go through one of the holes. Didn't fully think that one through as my dip tube lines up smack dab in the middle where the support pieces meet.

So now I'm going to get some bolts to use as legs that will have the false bottom sit above my dip tube. I haven't fully done the math, but this will triple the space underneath the false bottom.

That said - What is/are the downfalls of having more space beneath the false bottom?

 

[RM-MN]

Without recirculating that water under the false bottom is outside the mash. With recirculating the pores of the bag clog unless you mill more coarsely.

 

[IslandLizard]

I purchased it without the legs because i was thinking I would do like what is shown in this picture and have my dip tube go through one of the holes. Didn't fully think that one through as my dip tube lines up smack dab in the middle where the support pieces meet.

What's shown in the picture? Looks like the dip tube is just in the right place. Or something I'm missing perhaps?

Is that a compression nut on the diptube, which screws onto a (close) nipple? If so, and it's a little too long, maybe you can shorten the diptube a tad?

BTW, I would keep that dead space as small as possible.

 

[Rob2010SS]

What's shown in the picture? Looks like the dip tube is just in the right place. Or something I'm missing perhaps?

Is that a compression nut on the diptube, which screws onto a (close) nipple? If so, and it's a little too long, maybe you can shorten the diptube a tad?

BTW, I would keep that dead space as small as possible.

That's a picture of someone else's that they posted earlier in this thread. That's not mine. My dip tube goes right to the center of the "X" on the support pieces. Short of drilling a hole through the supports (which isn't a bad idea...), I can't get my dip tube in there. My system is the spike system with all tri clamps so there's no adjusting the length of the dip tube. It's all one piece. So my option is either drill a hole in the center of the "X" in the false bottom or buy legs for the false bottom and it will sit about 3" off of the bottom of the MT.

Without recirculating that water under the false bottom is outside the mash. With recirculating the pores of the bag clog unless you mill more coarsely.

I did just get a mill so I can set my gap to what I need! My system recirculates so not an issue there.

Other than the clogging, no other issues to worry about?

 

[IslandLizard]

That's a picture of someone else's that they posted earlier in this thread. That's not mine.

Sorry, I didn't realize the picture was from another post.

So my option is either drill a hole in the center of the "X" in the false bottom or buy legs for the false bottom and it will sit about 3" off of the bottom of the MT.

Drilling a 1/2" hole through the middle of the cross supports will certainly kill its function.

Is that false bottom made by Bobby? If so, maybe he can weld you one with one of the cross members at an offset, giving your diptube the needed space. That support cross doesn't have to be exactly centered to do its job. If in doubt, a double strip, one on each side of the diptube, would make it even stronger.

Are you saying there's a tri-clamp fitting on the inside of the kettle attaching to the diptube?

Are these double false bottoms supposed to be used without any legs? How big is that span?
I think I would have one leg in the center cross, at minimum. And in your case, under the off-center cross if you can get one.

 

[Jayjay1976]

That's a picture of someone else's that they posted earlier in this thread. That's not mine. My dip tube goes right to the center of the "X" on the support pieces. Short of drilling a hole through the supports (which isn't a bad idea...), I can't get my dip tube in there. My system is the spike system with all tri clamps so there's no adjusting the length of the dip tube. It's all one piece. So my option is either drill a hole in the center of the "X" in the false bottom or buy legs for the false bottom and it will sit about 3" off of the bottom of the MT.




I did just get a mill so I can set my gap to what I need! My system recirculates so not an issue there.

Other than the clogging, no other issues to worry about?

How are you heating the kettle? Reason I ask is because the bag can clog, the pump will either create a powerful vacuum that can damage the pot and fb, or if it sucks air down there you might get scorching.

I had the first issue, using that exact fb with 3" bolts for legs. It didn't collapse the false bottom but the pressure forced the legs down so hard it dimpled the bottom of my brew kettle. Dangerous accident waiting to happen, I barely caught it in time.

 

[Rob2010SS]

Sorry, I didn't realize the picture was from another post.


Drilling a 1/2" hole through the middle of the cross supports will certainly kill its function.

Is that false bottom made by Bobby? If so, maybe he can weld you one with one of the cross members at an offset, giving your diptube the needed space. That support cross doesn't have to be exactly centered to do its job. If in doubt, a double strip, one on each side of the diptube, would make it even stronger.

Are you saying there's a tri-clamp fitting on the inside of the kettle attaching to the diptube?

Are these double bottoms supposed to be used without any legs? How big is that span?
I think I would have one leg in the center cross, at minimum. And in your case, under the off-center cross if you can get one.

After looking at a picture of the false bottom, your right, there's a threaded hole for a leg right in the middle of the "X" so drilling a hole there is not an option.

Yes, it's from Bobby. I wonder if he'd let me return this one and order one like that..? It's worth a question I guess.

No, there is not a tri clamp inside. Here's a picture of the Spike MT and dip tube I have. The TC ferrule on the dip tube is welded so all I was saying is I cannot adjust how far into the kettle the dip tube reaches.

Not sure what you mean by a double bottom? The Spike MT has a lip on the inside of the kettle for the FB to rest on. It's either 3/8" or 1/2" off the very bottom of the kettle and that's what I was going to have this new FB from Bobby rest on, until I discovered the issue with the dip tube.

 

[Rob2010SS]

How are you heating the kettle? Reason I ask is because the bag can clog, the pump will either create a powerful vacuum that can damage the pot and fb, or if it sucks air down there you might get scorching.

I had the first issue, using that exact fb with 3" bolts for legs. It didn't collapse the false bottom but the pressure forced the legs down so hard it dimpled the bottom of my brew kettle. Dangerous accident waiting to happen, I barely caught it in time.

It's a HERMS system so it's recirculating through the coil in the HLT.

I have yet to have the bag clog so I'm not terribly worried about that. But I will keep that in mind as a concern. I dont' believe there's a scorching risk because there's no element there....

Interesting about the legs dimpling the bottom of your kettle!! That's no good... Not entirely sure about the way around that.

 

[IslandLizard]

No, there is not a tri clamp inside. Here's a picture of the Spike MT and dip tube I have. The TC ferrule on the dip tube is welded so all I was saying is I cannot adjust how far into the kettle the dip tube reaches.

Thanks, that's a whole different situation than I imagined. Better and much more elegant too.

Not sure what you mean by a double bottom?

I meant false bottom.

The Spike MT has a lip on the inside of the kettle for the FB to rest on. It's either 3/8" or 1/2" off the very bottom of the kettle and that's what I was going to have this new FB from Bobby rest on,

1/2" space under the false bottom ought to be enough to keep the recirc loop primed, but you need to keep a close eye (ear) on it. It depends on the keen balance between wort drainage from the bag and removal by the pump. If you were to raise the false bottom to 1-1.5 inch (now being placed above the dip tube) it may be a bit easier recirculation wise. But you must recirculate in that case!

 

[IslandLizard]

Yes, it's from Bobby. I wonder if he'd let me return this one and order one like that..? It's worth a question I guess.

Just thought about this, again.
Both cross members on that false bottom would need to be relocated. If doubled up, they'd leave a nice opening in the center for the diptube to peek through.

The "bottom" of the diptube is cut under an angle, right? So it can't suck up against the bottom of the kettle.

 

[Jayjay1976]

You could effectively shorten the dip tube by adding a short spool and second clamp between the dip tube flange and the kettle flange.

 

[Rob2010SS]

You could effectively shorten the dip tube by adding a short spool and second clamp between the dip tube flange and the kettle flange.

This is why I love this forum. You guys are some smart fellers! Brilliant!

Let's talk that though...

That would then mean the dip tube would not be in the center of the kettle anymore. As far as I can tell, there's no concave feature to the bottom of the kettle to ensure liquid flows to the center. That said, any issues with having a dip tube that's not in the center of the kettle?

 

[IslandLizard]

any issues with having a dip tube that's not in the center of the kettle?

Nope, I like it actually being closer to or along the sidewall, so I can tilt the kettle to get the last quart or 2 of wort out, and easier.

After the boil, the center of the kettle is also the center of your whirlpool heap, keep that in mind.

 

[Jayjay1976]

What size TC fittings are those? Looks like 1.5"? I have a bunch of Dernord brand TC hardware I bought on Amazon. Great quality and really good pricing. You'll need 1 spool, 1 clamp, and one gasket.

 

[Bobby_M]

You could also grab that same diptube that is meant for the next smaller kettle (I'm guessing 10G) and that will be about 2" closer to the drain. It's not incredibly important to pull from the center and that would be close enough.