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-   -   15 gal poly MLT project - False Bottom? (http://www.homebrewtalk.com/f51/15-gal-poly-mlt-project-false-bottom-304715/)

cbird01 02-16-2012 01:50 AM

15 gal poly MLT project - False Bottom?
 
I am buying a 15 gallon poly water container to use as an MLT. I will be cutting the top off and fashioning a removable top.

I am wondering how to install a false bottom with this setup, being that there is no concave bottom or ridge to install against. thx

http://arizonabarrels.com/images/15_...op_new3_lg.jpg

l3asturd 02-16-2012 02:27 AM

Quote:

Originally Posted by cbird01 (Post 3791195)
I am buying a 15 gallon poly water container to use as an MLT. I will be cutting the top off and fashioning a removable top.

I am wondering how to install a false bottom with this setup, being that there is no concave bottom or ridge to install against. thx

Jaybird makes false bottoms for coolers that come with a stand because of that reason. You should measure your inside diameter and go shopping at http://www.norcalbrewingsolutions.com/. Think he's also still offering free shipping but not positive.

day_trippr 02-16-2012 02:32 AM

If the bottom of that vessel is flat, you could use a domed FB...

Cheers!

cbird01 02-16-2012 02:57 AM

ok, so then it is cut to order. Makes sense

cbird01 02-16-2012 03:06 AM

Wow, pretty pricey. What's my other options? Can I do a manifold, without creating channeling?

pinback 02-16-2012 01:30 PM

i like that container. manifold is your most economical solution. make one that is big enough, and channeling shouldn't be too much of an issue

and what is your plan for insulation or maintaining heat? recirc/electric?

BargainFittings 02-16-2012 01:52 PM

You could use a mash screen like this one:

http://www.homebrewtalk.com/f51/55-g...1/#post1575665
Several good ideas in that thread.

http://i302.photobucket.com/albums/n...n/DSC00952.jpg

In my 50 gallon system I use a loop of silicone tubing connected with a piece of 1/2" OD stainless tube to hold up a stainless false bottom I made.
https://lh5.googleusercontent.com/-t...-22-47_755.jpg

cbird01 02-16-2012 02:37 PM

Quote:

Originally Posted by pinback (Post 3792413)
i like that container. manifold is your most economical solution. make one that is big enough, and channeling shouldn't be too much of an issue

and what is your plan for insulation or maintaining heat? recirc/electric?

I am an insulation guy, so I have materials available. I plan to use polyurethane spray foam insulation. We have 200 bd ft kits, which are for contractor use and much better application than the can stuff(which doesn't really apply well to a large flat surface area). I plan to add 1 inch, which will give me an R-5. I am going to test it and see if that is satisfactory.

I may add a layer of reflectix over that if needed. The thing I see people miss is that Reflectix has a very small R-value. The air space in the bubbles is actually only R-1.1(from conduction). The only way you get a value from it is if you are somehow stopping RADIANT heat transfer. In order to stop radiant heat transfer (which is heat transfer across an air space), you MUST have an air space. It barely helps if you wrap a MLT in Reflectix without an air gap. That air gap must also be air tight. So, I will install 1/2in furring strips around the foamed MLT, then a layer of reflectix. This will then be reflecting the radiant heat transfer from the heated up foam back to the MLT. The key is that air gap must be air tight, or Convection will ruin the whole gain by the Reflectix application. So, I will be sure to tape the seams well and have a space at the top, which is uninsulated so the tape can adhere.

cbird01 02-17-2012 07:12 PM

Quote:

Originally Posted by BargainFittings (Post 3792487)

In my 50 gallon system I use a loop of silicone to hold up a stainless false bottom I made.

What do you mean by a loop of silicone, you mean high temp silicone tubing, or silicone caulk? How much room do you need under the false bottom?

Where is a good source for the material to use for this. Also, how do you cut the circle with significant accuracy to prevent grains bypassing?

BargainFittings 02-17-2012 08:04 PM

I use a loop of 1/2" x 3/4" silicone tubing we sell under the false bottom to act as the seal.
A short piece of stainless steel tubing connects the two ends.

The false bottom is not tight against the side.
https://lh6.googleusercontent.com/-U...liconeloop.jpg

I don't direct fire the vessel so the silicone tubing works well to keep the grain from getting under the false bottom.


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