MIAB with Herms Coil

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Haze Crazed

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I’m getting ready to modify my HLT with Blichmann Boil Coil, Whirlpool Arm and HERMs coil so I have tighter control of my mash temperatures. I’m currently using a rectangular igloo cooler for MLT, finding a false bottom for a rectangular cooler is difficult. I have been using my old BIAB mesh bag for mashing and it works great. Makes cleaning up a breeze.

I’m wondering if any of you have similar setups. I’m concerned the mesh bag will want to suck into the upstream side of my MLT valve while recirculating. I suppose I could install a bazooka tube or something similar in the bottom of my MLT but I don’t want anything restricting flow while I’m recirculating during mash. Any suggestions or is this not going to be a problem?
 
You need a way to keep the bag off the entire bottom, not just out of the drain hole. You can make a coarse fb or manifold with large slots cut in the bottom. Almost anything that would keep the cloth off the bottom.
 
After talking to Rex at Brew Bag, the 400 micron bag he’s custom making for my cooler does not need a false bottom. I’m super impressed with their customer service! He picked up the phone on a Saturday at 12:30pm. I’ve bought all my bags from Brew Bag and will continue to do so!!!
 
I would reconsider. I'm sure Rex is a decent guy and answering the phone on a Saturday is commendable. I'm not even asking you to buy something from me so I don't have a dog in the hunt but do yourself a favor and test the assertion yourself. Run a batch with just the bag, then put SOMETHING in the bottom of the cooler. A single layer of glass marbles, a pile of stainless pipe fittings, A trivet, a colander. Then do that batch. The only way you can constantly recirculate without something holding the bag off the bottom and away from the bulkhead is to otherwise pull all the slack out of the bag so that it's not touching the bottom.
 
I would reconsider. I'm sure Rex is a decent guy and answering the phone on a Saturday is commendable. I'm not even asking you to buy something from me so I don't have a dog in the hunt but do yourself a favor and test the assertion yourself. Run a batch with just the bag, then put SOMETHING in the bottom of the cooler. A single layer of glass marbles, a pile of stainless pipe fittings, A trivet, a colander. Then do that batch. The only way you can constantly recirculate without something holding the bag off the bottom and away from the bulkhead is to otherwise pull all the slack out of the bag so that it's not touching the bottom.
Bobby this will be my first recirculating system so I’m trying to understand. If the bag doesn’t get sucked into the bulkhead what is the reason for needing space below the bag? Is this to prevent channeling? Or will I get a “stuck” recirc? Just trying to understand.

My cooler has a sloped bottom so finding a false bottom will be tough. I was considering buying some SS perf mesh off amazon then cutting to the shape of my cooler and using some SS screws through a few perf holes to hold off the bottom of the cooler.
 
If the bag doesn’t get sucked into the bulkhead what is the reason for needing space below the bag? Is this to prevent channeling? Or will I get a “stuck” recirc? Just trying to understand.
Yes, if the bag completely fills the mash vessel near the bottom, then the liquid flow pattern in the grain mash will "funnel" towards the wort drain, and you won't get significant flow in large regions of the grain mass. This is a form of channeling. And with all the flow concentrated near the wort drain, you have a better chance of grain fines building up in that area and slowing or stopping flow.

Brew on :mug:
 
Considering that I build (and use) recirculating systems that use bags that are supported by a very coarse mesh false bottom, the bags and grain bed already have a pretty hard time flowing enough wort through that 15" diameter separation area. That's what, 176 square inches of drainable area. The best we can really sustain through that over the coarse of an hour of recirculation is about 1-2 liters per minute. That's visually a trickle. If the bag touches the bottom of the cooler, any of that bag space doesn't drain. You'd be lucky to have like 1-2 square inches of drainable bag area right near the bulkhead drain. Recirculation = zero liters per minute about 10 minutes into the mash.

It is possible maybe to keep increasing the mill gap so that the grain particles are huge, but then your conversion time is going to increase to an unreasonable level.
 
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Considering that I build (and use) recirculating systems that use bags that are supported by a very coarse mesh false bottom, the bags and grain bed already have a pretty hard time flowing enough wort through that 15" diameter separation area. That's what, 176 square inches of drainable area. The best we can really sustain through that over the coarse of an hour of recirculation is about 1-2 liters per minute. That's visually a trickle. If the bag touches the bottom of the cooler, any of that bag space doesn't drain. You'd be lucky to have like 1-2 square inches of drainable bag area right near the bulkhead drain. Recirculation = zero liters per minute about 10 minutes into the mash.

It is possible maybe to keep increasing the mill gap so that the grain particles are huge, but then your conversion time is going to increase to an unreasonable level.
I really appreciate all the input from you guys. I’ll attach a picture of what I’m working with (until I get a new mash tun). Inner dimensions of my cooler are roughly 15-1/4” wide x 13-1/4 deep. The top of the hex nut is about 3-1/4” off the bottom of the cooler. Any suggestions for fabricating a false bottom that will get me to where I need to be from your experience?
 

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You're going to have an unacceptable level of dead space with that bulkhead up so high so whatever solution you use to keep the bag off the bottom can be combined with some kind of siphon tube assembly. It's a bit of a hassle to be honest.
 
You're going to have an unacceptable level of dead space with that bulkhead up so high so whatever solution you use to keep the bag off the bottom can be combined with some kind of siphon tube assembly. It's a bit of a hassle to be honest.
Do you think a bazooka tube would work?

The dead space will suck but I would still be able to pull the bag and tip forward the cooler to drain everything below. I generally brew for 12g beer to the fermentor so on NEIPA I using 30-34lbs of grain. So roughly 10.5g of water plus my grain would be tight but I think I could fit for mash. This cooler holds 15g.

I was thinking about getting this SS mesh and putting some screws with nuts on the opposing side of the bulkhead and resting the other side on the hex nut of my bulkhead. Any thoughts??
 

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Even if you can just friction jam a piece of hose into the bulkhead and have it dangle down to the bottom, along with that perforated it will work OK.
I know this is asking a lot but based on your experience building custom rigs for people I’d really value a quick call with you. I think I’d like to get a ripple coil set up from you vs Blichmann as their support was less than expected. Could you pm me with your number to discuss?
 
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