Herms setup coil spec

[federicovth]

Hi everyone.. first of all, please excuse my English but i'm italian, so i try to write the most exactly possible..

I want to create my own ag herms setup, but i have some questions that needs answers...

I want to work with a 3 pot setup: the first as HLT pot, second as MTH and filtering, and the third as BOIL..

My question is about the coil (located in HLT pot) specs: how long should be the tube and in which size?
My HLT pot is a 15 gal size pot, and my trouble is in having a coil that work properly and allow me to gain 1degree/min (max!!) during mash steps..

Thanks for help

 

[mredge73]

Bigger is better is the conventional wisdom, the more surface area the greater the heat transfer.
But there is a point where extra length has diminishing returns due to the flow rate reduction.
Here is a good write up to help you choose your ideal size:
https://www.brewpi.com/what-is-ideal-herms-coil-length-theory-experiments/

You will have to do some math to figure out how to get the 1degree/min gain. Your flow rate and coil will be fairly constant so you will need to determine your delta T.
For step mashes you would want a short coil that OD is close to the ID of your pot. This way you can use less water, so it will take less time to adjust your delta T between steps.

I have this coil in a 7.5 gallon pot, it works great for my purposes but I don't do step mashes. My pot has a ID of 12", the coil is 10" and is about 2" short of the lid. This is ok for me since I usually use 6 gallons or so of HLT water and don't use the HERMS to adjust the temperature; rather I use it to hold temperature.
http://www.stainlessbrewing.com/HERMS-10-Coil-with-2-bends-50-x-12-OD-Tubing-304-HERMS-_p_30.html

 

[day_trippr]

I run a 50 foot (~15 meter) long coil of 1/2" SS tubing (12mm?).
It only needs 10 gallons of liquor to be totally submerged in a 20g G1 kettle.
The length allows the hlt to only be a degree or two above the mash temperature goal, and there's more than enough rate-of-flow through it...

Cheers!