Why not build a HERMS like this?

I've been doing a lot of online searching about building a HERMS. I've noticed that just about everybody uses 1/2 or 5/8 copper coils in their HLT or HERMS tank to circulate their wort through. My question here is this: instead of circulating wort through the coil, why, why don't you circulate the hot water through a coil (say my 3/8 IC) inside the mash tun? My thought here is that it is easier to clean the outside of the coils off. If the mash temp is too high, shut down the water, and you wouldn't have wort still cooking away inside the coils in the HLT. I do realize that heat distribution in the mash would take longer to hit an equilibrium. Maybe a slow motorized mash paddle could solve this.
The reason I'm thinking about this is that I wouldn't have to build another coil for my brewery saving me a chunk of change since 1/2 and 5/8 copper are a bit pricey.

Some people do use their immersion chiller as a HERMS coil. All the recirculation of the mash is taking place pre-boil, so there's really no worry about sanitizing the interior of the coils. If you're using the same IC to chill the wort, it's going into boiling wort for 15-20 minutes, and then you're going to flush it out for a few minutes running water through it.

https://www.homebrewtalk.com/f51/use-immersion-chiller-herms-coil-189033/#post2193181

As you mentioned, the trouble is the thermal mass, You want to have a large thermal mass acting on a small thermal mass in order to get quick equilibrium, especially when the temperature differential is small.

I use my old 3/8" IC for my HERMS coil. It works fine.

Also, I don't have wort "cooking away" inside my coil when I brew because I always have the pump running and cycle the heat on and off. The wort never sits and cooks like you are suggesting.

As for stirring the mash to get better temp.... I thkn you would lose one major benefit of recirculating mash systems; wort clarity. When you recirculate, you are essentially vorlaufing for the entire mash. You would not believe how clear your wort is at the end of the mash because you have let the grain bed settle and are just filtering over and over and over through it.

In a lighter colored beer, I can look down through the wort at the top of my MLT and see the grainbed below it. Like a nice clear lake....

It's been pretty well documented that the clarity of the runoff has nothing to do with the clarity of the finished beer. It won't stay clear for long anyway. Throw some hops in there for the boil followed by a slug of yeast after cooling and it will be anything but clear. I've seen lots of brilliantly clear beer made using batch sparge methods where the brewer only vorlaufs briefly before running off the wort. I do agree that continuous circulation will normally yield a very clear wort, but I think the main advantage is for temperature control.

Catt22 said:

It's been pretty well documented that the clarity of the runoff has nothing to do with the clarity of the finished beer. It won't stay clear for long anyway. Throw some hops in there for the boil followed by a slug of yeast after cooling and it will be anything but clear. I've seen lots of brilliantly clear beer made using batch sparge methods where the brewer only vorlaufs briefly before running off the wort. I do agree that continuous circulation will normally yield a very clear wort, but I think the main advantage is for temperature control.

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Yeah, but the thing about "pretty well documented" things is that I sometimes find my personal experience to be very different. I trust my personal experience over documentation.

Walker said:

Yeah, but the thing about "pretty well documented" things is that I sometimes find my personal experience to be very different. I trust my personal experience over documentation.

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So you are saying that there is a correlation between clear runoff and the clarity of the finished beer then? I wonder why this conflicts directly with what the experts have to say on the subject. Very strange.

Indeed... in my personal experience, my finished beer has been clearer since I started brewing with a HERMS system, despite what the experts say. That's exactly why I said I trust my personal experience more than anything anybody else has written.

I'm not saying I'm right and they're wrong. I'm just saying that I trust what I see coming out of my taps.

Pre-conceived ideas can often be tricky that way. It's not at all uncommon.

You're right. I should probably just blindly trust the experts and stop trying to think for myself.

I read in some other online brew page that this one guy had his 3/8 tubing get clogged when he was circulating his mash through it...that sounded sorta strange to me. I would think that with the flow you would have it would clear the debris. Also, the only way I can see 3/8 getting clogged is if you didn't grind the gain or use a mash tun. I would think the particles would be very small considering my FB has 3/32 holes.
I do wonder if there is a benefit in heat transfer between 3/8 and 1/2 though.

, Do you guys vorlauf before circulating, or just let er rip? Will a march pump clog if you don't?

Hmmm, I guess that would could also help prevent clogging the heat exchanger.

I don't vorlauf before circulating. I stir it all up, and start pumping. But, I don't circulate with the pump's output valve wide open even though some suggest that it's fine to do so. (I had one mash get stuck on me). I keep the flow fairly low right from the start.

Walker said:

I don't vorlauf before circulating. I stir it all up, and start pumping. But, I don't circulate with the pump's output valve wide open even though some suggest that it's fine to do so. (I had one mash get stuck on me). I keep the flow fairly low right from the start.

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Not much allgrain experience, but from the last three books I've read, they say to keep your flow slow to better rinse the sugars from the grain.

Islandboy85 said:

Not much all grain experience, but from the last three books I've read, they say to keep your flow slow to better rinse the sugars from the grain.

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That's definitely true for the sparge process if yo are fly sparging, but for batch sparging and the initial circulating mash, I don't think the flow rate matters with respects to getting the sugar rinsed out.

I limit the flow because a stuck mash is a huge pain in the ass.

Walker said:

That's definitely true for the sparge process if yo are fly sparging, but for batch sparging and the initial circulating mash, I don't think the flow rate matters with respects to getting the sugar rinsed out.

I limit the flow because a stuck mash is a huge pain in the ass.

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Ok, I gotcha! I am planning on using my recirculating manifold (an H-shaped copper manifold ) on my mash tun as my sparge arm as well, so I will be fly sparging.

Walker said:

I don't vorlauf before circulating. I stir it all up, and start pumping. But, I don't circulate with the pump's output valve wide open even though some suggest that it's fine to do so. (I had one mash get stuck on me). I keep the flow fairly low right from the start.

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I had a similar issue with a stuck mash; I started to add water only, start circulating and then add grain, water, etc. This way if there is an issue I don't have to rake 20+# of grain. So far it has been working for me.... time will tell.

Walker said:

I don't vorlauf before circulating. I stir it all up, and start pumping. But, I don't circulate with the pump's output valve wide open even though some suggest that it's fine to do so. (I had one mash get stuck on me). I keep the flow fairly low right from the start.

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Same here. I just start real slow for about 5 min, by then its clear and ill up it a bit if i need the temp rise. If not i leave it nice and slow. What little debris is in the first runnings is so small i dont see how it could clog my 3/8" tube in the HLT.

As for the OP, the only issue i see with using a IC in the MLT is you will need to run 2 pumps during the entire mash. One to circulate the water through the coil and one to circulate the mash.

Not that its difficult, but just an extra expense to consider.

lazybean said:

As for the OP, the only issue i see with using a IC in the MLT is you will need to run 2 pumps during the entire mash. One to circulate the water through the coil and one to circulate the mash.

Not that its difficult, but just an extra expense to consider.

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Actually, I would only need a single pump if I used QD on my hoses, and had motorized mash paddle. I would pump the hot water from my HLT through the HEX and back to the HLT. Then I would move the hoses to the MLT, vorlaugh, and start my draining and sparging. I plan on a two tier system for now. If it was a single tier system, then you would be correct.

Is there a program or online calculator that anyone knows about that I could use to figure out which tubing diameter, pumping volume, etc is most efficient for my HEX?

I use 3/8" (25 feet) tubing in my eHERMS, and I've never had a clog. The only issues I've had was when I used a plastic quick disconnect. I've since switched to brass disconnects, and all is fine. I mash at 1.33 qts/lb and all is well. No clogs -- ever.

I turn the valve and let 'er rip for a 90 min mash. There's a 1 degree difference between my HLT temp and my MLT temp. I recirc my HLT with one of my two pumps. I measure my mash temp at my HEX-out right before it goes into my MLT.

Never had a clog, never had an issue. I hit my mash temps dead on.

OK, after a few hours playing in InkScape I've come up with this. My system will use camlock QDs, a 3/8 copper IC as my HEX, an unmodified sanke keg for my HLT/fermenter with the use of an adapter. What do you think?

http://i924.photobucket.com/albums/ad81/islandboy85/HERMS.png?t=1284445052

I would make the HEX coil a minimum of 3/8" ID. The 3/8" OD stuff will be too restrictive IMO.

Catt22 said:

I would make the HEX coil a minimum of 3/8" ID. The 3/8" OD stuff will be too restrictive IMO.

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How long should I make it if I use 1/2 or 5/8 tubing? 50 feet of 5/8 is expensive.

Islandboy85 said:

How long should I make it if I use 1/2 or 5/8 tubing? 50 feet of 5/8 is expensive.

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I don't have the expertise to advise you on the optimum length. My comment was based on a rig that my friend has. His uses the 3/8" OD tubing and the flow rate is way too slow IMO. The ID of that tubing is only about 1/4" or so. Yes, copper tubing is a little pricey right now, but it would be a one time purchase, so in that light, it's not so bad. I would guess that 25 ft of the 1/2" OD tubing ought to work pretty well, but it's only a guess.

Catt22 said:

I would make the HEX coil a minimum of 3/8" ID. The 3/8" OD stuff will be too restrictive IMO.

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My coil is 3/8" OD, but I forgot to mention that I did cut it into two coils that run in parallel because I was worried about it being too restrictive. 1/2" rigid copper pipe feeds down to a Tee which then reduces to the two coils of 3/8" OD soft tubing. Those coils expand and rejoin at another Tee and back to 1/2" rigid copper up and out of the HLT.

Walker said:

My coil is 3/8" OD, but I forgot to mention that I did cut it into two coils that run in parallel because I was worried about it being too restrictive. 1/2" rigid copper pipe feeds down to a Tee which then reduces to the two coils of 3/8" OD soft tubing. Those coils expand and rejoin at another Tee and back to 1/2" rigid copper up and out of the HLT.

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Got a picture? I'm confused how you joined the soft copper to rigid copper. I didn't think that you could join them together with sweat fittings. I thought you had to use a compression fitting with soft copper.

There should be pics in my gallery. I'm on my phone right now, so digging up a link for you ain't very easy.

Anyway... I had absolutely no problems soldering the soft tube into the fittings at all. Went together easily and no leaks.

Here you go:

Walker said:

Here you go:

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Sweet. Thanks. I may still just CL my current IC and just buck up and build one out of 1/2in.

I updated some of the design I have for my HERMS system. I'm thinking of having the HLT/fermenter and mash tun on a two tier cart, and then the BK/HEX on a regular burner so as to make it easier to store my system inside my apartment. My wife is just "thrilled" with my hobby.

http://i924.photobucket.com/albums/ad81/islandboy85/g7323.png?t=1284603561