HERMS Coil or CFC as HEX

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#brewlife

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Hi guys,

Im part way through my build and before i drill the holes in my kegs to install the herms coil i just wanted to ask a few questions and get some advice. There are a couple of threads with similar information but its hard drilling it down so hopefully someone has some direct advice for the below questions.

Should i install a typical herms coil in my HLT or double utilise my CFC as both a chiller for the wort and a heater for the mash?

If i go with the herms coil in HLT then i will pump sparge water (that is maintained at temp) out of the HLT through the coil and into the MLT. This will serve to clean and sterilise the coil to reduce cleaning time. This option would also allow me to turn the HLT into a CLT with ice water during chilling, and either run the hose water through the coil as a pre chiller before it goes into the CFC, or allow me to pump the cold water from the CLT through the CFC.

My other thought was to do away with the herms coil in the HLT and run the CFC as the HEX to keep the mash up to temp. This would still require the HLT to be keep at temp and i can still pump the sparge water back through the inside of the CFC to clean and sterilise during the sparge so its ready to go when i need to chill. I can still turn the HLT into a CLT and have both chilling options im just trying to simplify and reduce friction in the system.

Im also not completely sure how much water is needed during the CFC cycle to get the wort down to the desired temp, is this likely to be the same volume of cold water as hot wort or is it disproportionate? Having the option of both pre chilling or using the ice water as coolant is appealing because im yet to see the efficiency, Im in Brisbane so the summer is hot and getting down to temp off purely tap water might be difficult.

Any idea about optimal length for herms and CFC length?

Thanks for the advice guys. Keep brewing.

#brewlife
 

MHB

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Unfortunately its going to be nearly impossible to give you any simple answers, Thermodynamics is one of the most complex parts of brewery design.
Generally, purpose built equipment for each job works better than something adapted to serve multiple functions. For cooling a wort nothing comes close to the efficiency you will get from a plate chiller. For example a well designed plate chiller will get you from feed temperature (hot wort say 90-100oC) down to your coolant temperature (say tap water at 20oC) at a relative flow rate close to 1:1 (same a amount of coolant as feed); its going to be slow and most people want to get there faster so use more coolant.
To use a plate chiller as a herms would be a real pain; you would need two pumps a fair number of temperature sensors and lots of controls... Better to set up something simple like a coil in a small urn with a temp controller.

Questions like "optimal length" simply cant be answered without lots of other information, the material you use, for instance Copper is a way better conductor of heat than is Stainless, so a shorter Copper coil can work better than a longer Stainless coil. if the fluid is pumped slowly down a pipe you can get laminar flow (smooth flow) the liquid on the outside will heat up, the stuff in the middle wont, so a thinner tube might be more efficient than a thick one as you get turbulent flow and all the fluid comes into contact with the heated pipe walls. Tradeoff being you can get less fluid down the pipe.

That's only touching the edges, there are too many possible answers and way too many questions for anyone to give you a simple answer.
Take a long hard look at your system (draw out a flow diagram) define what you want to achieve at each step then look for the best answer to each step in the process, then ask some better focused questions.
Mind you this is the part of brewery design I find hardest, thankfully I do know experts I can ask silly question of and get back smart answers (if I bribe them with enough good beer).
Start with a simple functional design, preferably one that is well tested, run it and look for ways to improve the system over time.
Mark
 

#brewlife

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Thanks for the detailed answer MHB.

My current plan is to go ahead and build the 1/2" herms coil inside the HLT and the 1/2" convoluted CFC. Ill probably do the CFC as a parallel arrangement so it can be expanded if necessary but dont think this will be necessary with the prechiller and chilled water options built in. The herms coil length will be dependant on what i can fit in my HLT and still stay below the 5gal / 20 l mark.

Ive got a flow diagram that I've been working on and i could probably rationalise some of the valving but i like the idea of having isolation at inlet/outlet of each piece of equipment. The idea was to hard pipe a valve manifold front and center of the rig for easy access. If you have any comments id appreciate them.

Cheers.

Screen Shot 2018-09-29 at 9.47.06 am.png
 

MHB

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Interesting, just out of curiosity where does the wort come out of the system?
I suspect you are going to run into some complexity issues, I would build each part and hook it up and operate it on flexible hoses I/O the pump/s. Keep good noted on what you need where/when then revise the connections before hard plumbing.
The HLT would be best with an element and controller, trying to keep consistent temperatures by drawing on hot water from the kettle will be problematic.
Have Fun!
Mark
 

TwoCrows

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From what I have read and if I do build a HERMS, the use of a small HERMS hot water vessel is the way to go. The 1/2 inch coil @ around 8 mtrs in length and submerged in approx 8ltrs water bath. This will help maintain constant temps. Heating and maintaining smaller volumes of water separate to the HLT is necessary for a flexable brew rig.....
This is only my two cents...
 

#brewlife

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MHB,
Good point on the wort outlet. Oops I missed that. Still tossing up about the post boil procedure, wether it’s whirlpool while chilling then dump to fermenter or just whirlpool then chill straight to fermenter. I was planning on going flex from the valve manifold to the tanks to make cleaning easy but yeah your right, I want to keep it all flex to start then build it up slowly an see what works.

TwoCrows,
I’ve spoken to a couple of guys who do this and swear by it, I’m just hesitant as I want as few tanks as possible but this might be a good and efficient way forward. Do you know if the 8m in 8l is enough for a 40l brew? I’m currently converting some 50l kegs into keggles so anticipate a max40l brew session.

Thanks for the input guys, I’ve been flying solo till now.
 

TwoCrows

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you mash in with the temp required and then maintain mash temp. Mash out should be able to raise temps, but duration , not sure.

He is a youtube video with home made HEX and brew rig.

 

#brewlife

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you mash in with the temp required and then maintain mash temp. Mash out should be able to raise temps, but duration , not sure.

He is a youtube video with home made HEX and brew rig.



This is a great video, thanks.

I notice he doesn’t do a mash out before sparging. With the coil in the HLT youd bring the mash up to strike temp over 20 min prior to sparging.

Any thoughts on pro’s con’s of this.
 

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