Herms Coil Sizing

[rehabs_for_quitters]

Just getting together the bits to finally build a 3V herms rig and was going to use a combo of gas and electric,

In the HLT I am going to run a herms coil just so I don't need to make another vessel to house the herms coil, now what size coil would suit I am going with a 100L HLT and 100L Mash Tun and 150L kettle, I found a 50 foot coil of 1/2" stainless on Aliexpress for bugger all would that be enough to do the job, I am going to run a gas burner for ramping and 2500w element for holding temp in the HLT if that has any relevance

 

[TheWiggman]

What batch sizes are you doing? It's a slightly open ended question and no doubt you'll get a stack of anecdotes and differing opinion, but...
3m for 23l batches is adequate.
By extension, with a 150l kettle I assume 100l batch so about 8m would probably be overkill.
You'll be limited by the heat power in your HLT and flow rate in your pump. A stronger pump and more coil will aid in ramp times, to a point. Many variables. Personally I wouldn't go any less than a March and about 5000W in the HLT.

 

[rehabs_for_quitters]

Going to be aiming for 75 to 100L batches and some bigger beers hence going 3V going to use March or Chugger pumps the hlt will have 33kw of heat via a burner up its date and 2500w element just to try and hold temp more consistently, probably get some wooden insulation to turn it into a hot tub so hoping the 2500w will do the job and use the gas for ramping up and getting to strike temp,

so you reckon 50 foot is over kill?

 

[dicko]

It wont be the length of tubing that you will have problems with, it will be accurately controlling that mass of water in the HLT so that you dont overshoot temps.

I had a herms coil in a 10/12 litre pot with 7 feet (2 metres) approx of 13 mm ID pipe with a kettle element of 2000w.
It ramped at approx 1 deg per min and was easily controlled with a digital controller.

 

[rehabs_for_quitters]

Yeah just going to be using Sestos PID's on it to control the temps so should be pretty close to bang on all going to plan, and will have a secondary PID for the gas burner to shut that off guessing about 5 deg C below mash and mash out temps to avoid overshoot,

I am just really trying to build it once and try to get it as close to right first time so I only have to tweak not do anything major to get it right,

 

[boybrewer]

They say that copper has a better heat transfer than SS . I have 4mt of 1/2 inch copper in a 7lt pot and the ramp time is 1degree per 56 seconds . So having 50 foot of SS in a 100 lt pot is going to be a little hard to control temps and keep the ramp up at a consistent rate , most HB ers ramp at a rate of 1 degree per min . If you decide to go the whole hog then put a stirrer in the HLT this will give you a more even temp throughout the whole pot but your ramp times may be a little slow .

I have no knowledge of the maths so I could be completely wrong as common sense always prevails . Its not how big , its how much is enough .
I am sure that there is someone on the forum who can give you the numbers on SS heat transfer per foot or meter .

Anyway enjoy the build . Its a lot of fun and learning .

 

[Smokomark]

Any length will work.The smaller volume of the herms vessel the better to avoid ovvershoot.I use a 5 mt ss coil on my 100lt setup.

 

[TheWiggman]

so you reckon 50 foot is over kill?

Jonah Falcon overkill.

 

[Adr_0]

Any length will work.The smaller volume of the herms vessel the better to avoid ovvershoot.I use a 5 mt ss coil on my 100lt setup.

Bingo. Big volumes of water are nothing but bad news: slow ramp times, overshoot and a stupidly big element is needed.

Try to keep it small, with good flow going through. 3/8" copper is great as you get more turbulence for the same flow, can fit more in and it's cheaper. Harder to get though, and harder to get fittings. 2m should be fine. As the Wiggman said area, flow and differential temperature will all help heating power.

If you keep the water volume small, decent flow and keep the coil close to your probe and the mash tun your controller with thank you for it, and you won't be pulling your hair out with slow ramp times and overshoot.

 

[Adr_0]

Yeah just going to be using Sestos PID's on it to control the temps so should be pretty close to bang on all going to plan, and will have a secondary PID for the gas burner to shut that off guessing about 5 deg C below mash and mash out temps to avoid overshoot,

I am just really trying to build it once and try to get it as close to right first time so I only have to tweak not do anything major to get it right,

It doesn't matter how good your controllers are, if your system is not responsive you will have iissues.

Keep your coil as close to your mash tun as possible, keep your coil water volume as low as possible, measure temp ascclose to where the coil comes back into the mash tun...and keep good flow going through the whole time. Insulate your lines too.

I've always thought it would cool to have feed-forward control measuring temperature going into the coil, then feedback on the return side. Not sure how to do that though...

 

[elcarter]

Good info here, I went to a larger 20L urn when the 10L died.

I added more coil but the water mass is slow to heat up and my ramp times increased dramatically. Also need to select a degree below desired temp to counteract the small overshoot.

Now modifying to displace / reduce water to help the thermal efficiency before adding more power.

 

[dave81]

If all you want do is single step mashs then just go a herms coil in your hlt=slow ramps times (depending on size of coil and element , volume of water)also as said , so you don't end up with hotspots in a lrge volune5 of water it willl need to be recirculating somehow.1 more thing , just because you can increase the temp of the hlt at a certain rate it still takes time to transfer that temp through the mash

 

[Smokomark]

Any length will work.The smaller volume of the herms vessel the better to avoid ovvershoot.I use a 5 mt ss coil on my 100lt setup.

Any length will work.The smaller volume of the herms vessel the better to avoid ovvershoot.I use a 5 mt ss coil on my 100lt setup.

My herms volume is 1.5lt, Very quick reaction and no overshoot.

 

[Cocko]

The conversion of your mash will happen at the hottest point of your mash/system.

So, if you are running a 100m coil, you would want to make sure you measure the temps all the way along the coil....


Small, efficient coil sizes are starting to prove to be beneficial for materials, efficiency, cost and clean ability... Nevs HERM-IT seems to be a great balance of these things.

I have run a RIMs or 2 in my time [Snide remarks to follow] but as far as consistency, ramping, holding and temp times go..


My advice is go a separate vessel for running your coil, make the coil smaller so you can control it better....

2c.

 

[Camo6]

^ Sound words from a born-again.

HERMSELUJAH!

 

[rehabs_for_quitters]

So the basic gist is it'll give me the ***** and trying to be clever lazy by using the HLT as the herms as well is going to cause a brewing headache, I shall find myself about a 10ish litre vessel maybe a 10L corny to house some coil which really isn't a major as I have a spot right under the mash tun that'll be about right so I don't have to modify my already cut stainless for the stand,

Will have a look at the Herm it coil as it might well just make life easier going that way

cheers for the advice,

 

[dicko]

So the basic gist is it'll give me the ***** and trying to be clever lazy by using the HLT as the herms as well is going to cause a brewing headache, I shall find myself about a 10ish litre vessel maybe a 10L corny to house some coil which really isn't a major as I have a spot right under the mash tun that'll be about right so I don't have to modify my already cut stainless for the stand,

Will have a look at the Herm it coil as it might well just make life easier going that way

cheers for the advice,

I wish that this knowledge was around back in the early 2000's when I built my first herms in my HLT.
What a waste of time and effort that was...
Never looked back with the small herms and the element and digital temp controller.

 

[rehabs_for_quitters]

yes indeed that's why I tend to over research first, my first BIAB rig took me way to long to design and think out, gas fired recirc system with cheapo STC for temp control, pretty much spot on out of the box except when pushing the limits but that's no surprise, that's the beauty of forums like this getting the right info that's tried and tested and much appreciated

I was going to build a Brutus 10 then have changed my mind a few times as I think herms will give me the best results and by the time I stuff around with another burner and solenoid and all the sundries it'll actually work out marginally cheaper for a better rig, pretty much a win win in my books, and the plus is I am in no rush as the BIAB rig is still pumping out 40L batches comfortably :chug:

 

[mckenry]

So the basic gist is it'll give me the ***** and trying to be clever lazy by using the HLT as the herms as well is going to cause a brewing headache, I shall find myself about a 10ish litre vessel maybe a 10L corny to house some coil which really isn't a major as I have a spot right under the mash tun that'll be about right so I don't have to modify my already cut stainless for the stand,

Will have a look at the Herm it coil as it might well just make life easier going that way

cheers for the advice,

Well, a little contrary to most of the advice above, but I do exactly what you are planning to do, except 50L HLT with SS coil in that and a 2400W element. (I run 15A anyway). 50L mash tun and 80L gas fired keggle.
I never have any problems with overshoot, but my ramp times are more like 2 mins per degree.
It works fine and if you're only doing single infusion, no mashout, who cares? I don't. I'll typically do 55 65 72 76. I have done the full zwickle wheat mash schedule, which was a longer than normal day. It doesn't bother me though, as I'm familiar enough with my system to know I have 20 mins to do the whipper snippering, hang the washing out etc. while it ramps from 55 to 65. Quick check that it hit the 65° and switched to bypass, set the timer for whatever time I'm keeping the mash at 65° and get back to the chores or do something else around the brewery.
What I really like is I can set the water the night before, put the rig on a timer and have it start heating the water in the HLT and MT and its ready for mash in when I wake up. I wouldn't do that with gas though.
I think your original plan will be fine, just allow for longer heating times for strike temp etc. If time is an issue, look at the smaller HEX / extra vessel option. Really though, the extra half hour in ramp times in a four step mash is ok by me.

 

[TheWiggman]

I agree mckenry, overshoot is not the problem but ramp times. Overshoot can be controlled (by PID) but it'll slow ramp time. Ramp time is limited by the volume in your HLT, hence the smaller the better argument.*

* Note this applies to HLT volumes you dirty bastards