Dedicated Herms Guide, Problems And Solution Thread

[mb-squared]

Moad, are you set up with two pumps? You'll need a water pump to keep the water in the HLT moving. Otherwise you'll get "cold" spots in there right around your coil.

In my experience, once the HLT is up to temp, you'll have zero problems maintaining the temp in the HLT regardless of how fast you're pushing the wort through the HEX (at least with my 5.5KW element).

Again, in my experience (with a wimpy chugger pump and 15m of 1/2" copper in the HLT), the MT temp lags behind for the first 15~20 minutes, but then it reaches equilibrium with the HLT temp. I've heard of some systems where the MT is always ~1 degree behind so they just set the HLT 1 degree higher, and mine used to be like that when I brewed outside. Since moving indoors, I've found that the HLT and MT temps are identical after the first ~15mins or so.

I suspect with that massive false bottom that you ordered in, you'll be able to turn the MT volume over pretty fast, so you'll be ramping faster than me -- though it sounds like you need to increase the size of the inlet to your wort pump to a minimum of 3/4". on my new pump I'll be feeding it with 1" tubing.

keep us posted with real-world results!

 

[Moad]

3 pumps... One dedicated to HLT (recirc in HLT then sparge) and 1 (potentially 2 in parallel) for moving wort to improve flow rate.

Yep that makes sense what you are saying, it will take 15 minutes for me to get a full cycle of mash through the HEX so that makes perfect sense it would lag at least that much.

the HLT set point relative to MT will be a little trial and error, I was factoring in some loss through silicone tubing from HLT>MT etc but it could well be that it is the same temp.

Thanks heaps Matto, I'm feeling a bit more comfortable with the setup after going through it in detail with Tex and reading your reply

At the end of the day, if the coil isn't cutting it I can add a Herm-IT on a separate circuit or shorten the HEX coil or add a larger diameter coil. There are options

 

[TheWiggman]

Point 1 is a bit misleading. The HLT will heat at a faster rate because it is smaller so it will be 'at temp' before the mash will be. If you to calculate overall energy required to raise the temp then yes, you'd just use both volumes + losses to atmosphere.
Point 2, I'm referring to the difference between the temp of the mash (i.e. temp going into the HEx) and the return temp from the HEx. The temp coming out of the coil will be greater than the temp going in - of course - but I don't think you'll lose anywhere near 1°C between the coil and the MT.
You'll probably find the HEx outlet temp will be almost exactly the same as the HLT temp because 15m is a hell of a lot of coil in this application. That's not a bad thing, worst thing is you'll lose a bit of flow but it sounds like that's not an issue.

The other thing to consider is the time will be greater than calculated because the PID controller will slow to prevent overshoot. As a comparison, my system has a 2000W element and it takes me about 45 mins to heat up 15l of 20°C water to 58°C. The calculator you linked says it should take 20. Extrapolating, in your case I would guess it would take about an hour - 6 x the volume, 4 x the power of my system. However I reckon you'll get the temp you're after at the HEx outlet much sooner than that.

 

[Moad]

Thanks Wiggman, I guess I was assuming the heating wouldn't be what would be slowing the ramp rates which seems to correlate with Mattos setup.

I see, I have put a lot of faith in that calculator. I accept some variation but double the time to ramp would piss me off!

I guess it is a leap of faith, so many variables mean I'll likely have to wait to test it out real world and modify from there.

 

[mb-squared]

I've never used that calculator but here's my real-world experience. I fill up my HLT with ~40L of cold water (I've been told to never use hot tap water!) and my MT with 30L of cold water. I turn on both the water and wort pumps as well as the 5.5kw element in the HLT. Actually, I start the "get mash-in temp" function on my BCS. I then turn around, weigh out my grain, mill my grain and measure out my salt and acid additions. Right about the time I finish up those chores, the BCS starts dinging, letting me know that my MT is up to temp.** I'd say it takes somewhere between 30 and 40 minutes.

**Moad, note that I set up the BCS to cycle the element on/off based on the temp probe at the HLT-out valve, but the "get mash temp" process doesn't exit until the temp probe in the MT has reached my desired 'mash in' temp. Again, that's ~15 minutes after the HLT has reached my desired temp.

 

[Moad]

I'm hooking up a Hot Water System to feed the HLT so no dramas there! Good to know though...

I'll be almost at strike temp instantly with the HWS in play

8KW of heating in the HLT as well, I think the weakest link is the flow rate through the coil

Edit: With regards to the BCS, that should work fine on my ststem as well as PID will be confused with the mash through the HEX pulling the temp back down. Do you get any overshoot? I was planning on doing this for mash steps as well

 

[Screwtop]

A brewing mate with metal fab skills made this fantastic wort return manifold. It sits on top of the grainbed, the flexible hose allows for varying grainbill size, outlet holes in the top of the arms distribute wort evenly over the top of the grainbed with no disturbance. So well made, all stainless, easy to use and clean. Ordered one from him for my HERMS Brewery.

Screwy

 

[Benn]

Looks good Screwy

 

[Moad]

Well I got around to hooking up the pumps and running a flow test through the coil.

6L / min back into the Mash Tun.

Looking forward to hooking the elements up and seeing what kind of heat transfer I get through the coil.

Flow rate 6L/min
Mash volume 80L
HLT Volume 100L
Total volume 180L
Elements 8KW

So it should take around 15 minutes to step a degree. I will need to see what kind of temp transfer is possible through the coil. will it transfer 4 degrees from the HLT through the coil and return to the MT for example. Is this evendesirable? I've seen the 1 degree per minute thrown around so is that what I should be ramping the HLT at and not have a large differential between HLT and MT.

 

[Adr_0]

So you have 1 x 8000kW? How many metres of coil do you have?

Are you controlling HLT/coil vessel, wort return line or mash tun? If you don't have control do you have indication?

 

[Mardoo]

OK, as a prelude, I am Not-Physics-Man here, so my question may be a bit ham-handed.

Moad's question has raised a question I have, about effective flow rate. If I use a HEX coil with a smaller diameter tubing, but move the same amount of wort through it, I'm effectively increasing the flow rate through the heat exchanger, yes? For example, if I move 6L/min through a 3/8" diameter coil, and 6L/min through a 1/2" diameter coil, wouldn't the heating efficiency of the HEX with the 3/8" coil be greater, at least insofar as efficiency relates to flow rate and heat uptake relates to tubing diameter?

 

[malt junkie]

6L/min for a 80L mash is probably not enough. Much like throwing stones at a tank. Though you'd only see significant increase with one of the nano pumps from either chugger On brewhardware site @ US$324 (a little cheaper but out of stock) or March On the morebeer sight listed @US$780. Both expensive options. Your other considerations if you do go a bigger pump; would be size of FB versus flow rate. As with all these kind of pumps the inlet needs to be as open and large(hose wise) as practicable to get the best performance. Note one of these will run CIP on any other gear you have or might get.

There maybe another solution??!!??

 

[Moad]

3.5 and 4.5kw in the HLT.

i've got 1 inch hose into a 1" tee into 2 x march 815-C pumps out to another 1" tee into !" hose then into the coil in the HLT.

the coil is 1/2" 50ft stainless

edit: with the nano pumps i'd probably need to start looking at a grant or i'd be pulling down on the grain bed i think.

my realistic options are to increase diameter of the coil or shorten it.

will wait and see once i can run some tests with elements hooked up

 

[malt junkie]

Moad note that ramp rates are lineal, no system can do a 1 deg step at 1deg/min unless they are able to recirc the entire volume or more in one minute. Heating I think your well covered. I would check with a few of the guys as to what flow rates they're working with, I'm sure most with 30cm falsie are running wide open without sticking, your FB would have much more surface area, so 12+LPM should be doable

 

[TheWiggman]

OK, as a prelude, I am Not-Physics-Man here, so my question may be a bit ham-handed.

Moad's question has raised a question I have, about effective flow rate. If I use a HEX coil with a smaller diameter tubing, but move the same amount of wort through it, I'm effectively increasing the flow rate through the heat exchanger, yes? For example, if I move 6L/min through a 3/8" diameter coil, and 6L/min through a 1/2" diameter coil, wouldn't the heating efficiency of the HEX with the 3/8" coil be greater, at least insofar as efficiency relates to flow rate and heat uptake relates to tubing diameter?

Same amount of wort means flow rate is the same (ya duffa). You are increasing the flow velocity. With a smaller diameter coil the fluid will spend less time exposed to the HEx, but will be more turbulent and will have a higher surface:volume ratio. Long and short of it: smaller coil is better for the same flow rate. In reality using a typical home brewing centrifugal pump will mean the smaller coil will choke the flow, and which is better I can't tell you without some proper engineering.

 

[Moad]

What I meant was I can turn the whole volume of MT over in 15 minutes. So then I thought if the differential is for example 10 degrees, would I be able to raise the entire volume 10 degrees in 15 minutes assuming heating was covered. In other words, how efficient is the coil going to be.

Ill have to wait and see it seems there are too many variables.

I will go the nano pump if necessary but I'm not ruling out current equipment yet. Getting so close to finishing this thing

 

[mofox1]

Hey Moad, I have a smaller but similar setup...

46L (max) mash
88L HLT w/ 50' coil
5.5kw elt in the HLT
Approx 5L/min using a kaixin (kegking) mag drive pump

I usually run the HLT with around 70L in it (for a double batch). The HLT by itself (no mash recirc) will ramp at more than 1deg/min (at 50L it ramps at 1deg per 45 sec). Most times I will mash in either using hot tap water (~55deg) or similar temp water from the HLT. While stirring in the grains I have the HLT heating to sacc temp (~65). By the time the grains are all stirred in and left to settle for a bit, the HLT has reached target temp. When I start a slow recirc I'm getting pretty much target temp coming out of the coil. When I open up the pump throttle all the way I'm still getting near target temp (usually a couple degrees off when there is a 10deg diff between HLT and mash tun out).

Previous to last brew it took 22min for the temp at mash tun outlet to go from 52deg to 63deg, the target was 65. I was getting 65 out of the coil out / mash return within 10min. Unfortunately, I got a stuck mash (f'k u rye) at around 20/30min and stopped taking temp notes from the mash outlet. This was 13kg grain in a total volume of around 42L (~2.5 - 3.0 L/kg). The next brew I did (~10kg @ 3L/kg) started at 55, I didn't check any temps until 20min later and the mash tun outlet was already it target temp 68 (same as HLT).

I don't do too many stepped mashes, but ramping doesn't seem to be too much an issue. Even when recirc'ing the 5.5kW elt will ramp the HLT by a degree/min, wort temp out of the coil is very close to to HLT temp unless there is a massive temp diff between grain bed and HLT...

Long story short - it'll be fine (probably - your mash tun *is* larger). Just because it takes 10 / 15 min to recirc the entire mash volume, your wort return closely follow your target/step temps. You'll get much better than 1 deg/15min, (more like 0.5L/min when reading @ coil out) it's just the lag time to get that temp out from the bottom of the grain bed is obviously dependant on flow rate which is in turn dependant on coil length yada yada...

I keep saying I will do an accurate (and complete) recording of brew day times and temps... but I usually start downing a couple half way through and lose (or re-order?) priorities. C'est la vie, non?

 

[malt junkie]

mofox more rice hulls with the rye

 

[Moad]

Thanks for the detailed reply mofox, do you find any issues having a large differential between HLT temp and the mash liquor coming through the coil?

What's the 1 degree per minute? Is that only if direct fired MT?

 

[mofox1]

Yeah, on reflection the post was probably a little "tldr". The 1 deg/min is the ballpark rise in the HLT when stepping the mash from one temp to another. A bit slower than when just heating the HLT alone.

No direct fire here, all electric. Mash heats from coil in HLT.

I reckon the large differential works well. I go from a lower temp to mash in (much less issues when doughing in), and then basically boom up to sacc temp for the liquor returning from the coil. It still takes some time to bring the total mash volume up to temp, but the "hot" liquor basically percolates down. You don't see much change for the first few minutes, then it starts rising up to target.