Dedicated Herms Guide, Problems And Solution Thread

[TheWiggman]

Minimise water volume in the heat exchanger, maximise flow, maintain flow to prevent scorching.

Point: any change that is consistent with the above will improve performance for a given input power when using PID.

 

[Camo6]

I'm just trying to simplify it.[/font][/size]

An engineer just trying to simplify things? Now that's a juxtaposition if ever I've seen one!

 

[idzy]

Minimise water volume in the heat exchanger, maximise flow, maintain flow to prevent scorching.

Point: any change that is consistent with the above will improve performance for a given input power when using PID.

This has nothing to do with anything that I said or the question asked. Flow =/ Coil.

An engineer just trying to simplify things? Now that's a juxtaposition if ever I've seen one!

Too true.

 

[TheWiggman]

Who said I was an engineer?!
There's no cruel intent here, forgive me if I'm coming across the wrong way (and also can't see you asked a question). Not sure what =/ means either, not equal? Minimising water volume in a HERMS has everything to do with what you said except for the comments around power.

I'm trying to cover all bases with a simple statement. For example if you want to minimise water in a HERMS then you could -

• Maintain HERMS volume and tube length but increase tube diameter
• Maintain HERMS volume and tube length diameter but increase tube length
• Maintain tube length and diameter, reduce vessel size

How each person goes about it is up to them, but the principle remains the same.

 

[Adr_0]

[Things] should be as simple as they need to be, but not simpler - Einstein

I think people can fall onto some issues if they go down a rabbit hole and don't quite understand the mechanics, or lose sight of their original intent or what's important.

While I'm against complication, if you really want to learn then things will get complicated, but it's important you just use the key points you have learned and see if there is a gap or opportunity in your system - if that's your goal or if that's important to you. Simple is best as long as you know why you're making decisions.

I reckon it would be a nice easy/effective way to move to HERMS with a 2.4kW kettle and trying to stuff 2.5-4m of 3/8" copper coil in there. Cheap, simple, effective.

If you want to go with a big HEX/HLT because it's handy to have some strike water, aim for the 10-18m mark with 1/2" rather than the 2-5m mark.

I like getting value out of my element - a 2200W element should get something like 1.4°/min with a 25kg mash. In practice with my RIMS I get 1.1°/min with a 2200W. If I were getting 0.5-0.7°/min and was limited to 10A, I would be wondering what the hell's going on and what I can do about it... but I appreciate that might not be important for the next brewer.

 

[Camo6]

Who said I was an engineer?!

You don't need to my friend. Some things need not be spoken.
Although...an engineer who doesn't tell everyone he's an engineer is another juxtaposition in itself!

(All tongue in cheek. I have engineer friends who are sometimes fun to be around.)

Oops, there I go again.

 

[Camo6]

Here's a couple of pics of my new 5star 3.6kW element mounted vertically in my HEX. Initial trials with water seem promising although the PID was overshooting a bit and will need fine tuning once I test with standard volumes.

The element is slightly off centre due to the existing hole being 40mm so comes pretty close to touching the coil. So close that it's kind of like a RIMS wearing a SS condom. I used silicone to help it seal so can't be bothered centralising it any better for now.

When ramping 50l from 12c to 65c the HEX water never boiled.

 

[Mardoo]

What's that HERMS housing Camo6?

 

[Camo6]

A retired 'essential oils' refinery a mates Dad buried in the backyard before he passed. Basically a bit of 150mm SS pipe with a collar soldered on. I cut it and welded the base a bit higher. Works a treat. 100mm pipe would probably be a better fit but I'm a tight arsed improviser!

 

[Adr_0]

That looks awesome, and saw the rest of your rig in the brew controller thread.

How long is your coil, and is it stainless or copper?

I would still recommend dropping the I to 0 regardless. You could probably drop the D as well to be honest, and just try the P at 100. If it overshoots, bring the D up to maybe 50-60. If it still overshoots, drop the P to 50-80. I have a feeling you will just get away with P though.

 

[Camo6]

That looks awesome, and saw the rest of your rig in the brew controller thread.

How long is your coil, and is it stainless or copper?

I would still recommend dropping the I to 0 regardless. You could probably drop the D as well to be honest, and just try the P at 100. If it overshoots, bring the D up to maybe 50-60. If it still overshoots, drop the P to 50-80. I have a feeling you will just get away with P though.

Cheers Adro, I was going to hit up your thread if there was no improvement next time I fired up the rig. Time is something I don't have much of ATM.

The coil is one of Nev's so only a couple of metres in a HEX of about 4-5 litres running a 3.6kW element.

Initially the PID was maintaining set point with a .5 degree swing either side. I ran the autotune feature but this didn't make much improvement so I manually set the PID values to P=300, I=0, D=25 as I'd read in your thread. This increased the overshoot and caused some erratic operation with the PID outputting while the temp was still above setpoint. I played about with the settings but didn't drop P as low as 100. In the end I ran another autotune and got back to where I started and figured I'd give it another go in a week or so.

 

[Adr_0]

Bugger, was hoping you had more than just a couple of metres (stainless?). Those settings (P 300) with that coil would not be pretty. Very sorry about that.

Two options:
- try P 30-40, D 100; or
- lengthen your coil to 4-6m and try just P of 100.

 

[Camo6]

Bugger, was hoping you had more than just a couple of metres (stainless?). Those settings (P 300) with that coil would not be pretty. Very sorry about that.

Two options:
- try P 30-40, D 100; or
- lengthen your coil to 4-6m and try just P of 100.

Nothing to apologise for mate! Those settings were posted by another brewer with a similar setup so I used them as a starting point. Will have a try at those lowered settings next time. Cheers!

 

[Moad]

Hey guys I haven't read the whole thread so if someone has a guide please let me know.

I currently run a 3v with the coil in the HLT however find the ramp times to be poor, also a pain having to direct heat the MT when the HLT is set to sparge temp.

I'm looking to build a new HERMS setup to knock out 120L. It looks like I'll build a separate HERMS vessel to go 4v, how do I go about sizing it appropriately?

 

[Tex N Oz]

The most important factor is the conductivity and mass of your heat exchanger. I'm missing the "scorch" aspect of it though. Our median is water at atm pressure right?

 

[Tex N Oz]

Hey guys I haven't read the whole thread so if someone has a guide please let me know.

I currently run a 3v with the coil in the HLT however find the ramp times to be poor, also a pain having to direct heat the MT when the HLT is set to sparge temp.

I'm looking to build a new HERMS setup to knock out 120L. It looks like I'll build a separate HERMS vessel to go 4v, how do I go about sizing it appropriately?

How many kW is your element and what volume of water is in your HLT?

 

[Moad]

Currently gas fired but rebuilding as electric with new pots. I think 100LT HLT will be plenty

 

[Adr_0]

Element sizing is pretty straightforward:
kg water x 71 x desired degrees/min = watts.
kg wort x 65 x desired degrees/min = watts.
Obviously round up. See what the numbers come out at and what your circuits are capable of. The 71/65 are just simplified heat capacity/time factors.

Keep in mind your HEX/coil is will erode that theoretical rate (because it's not 100% efficient, more like 20-60%), while you should be fairly close to hitting that rate with the water. So 1.5-2 is probably a good target.

Ramp rates:
Faster with increased pump circulation
Faster with greater coil length
Faster with more powerful element
Faster with reduced HEX volume*

I starred the last one because you can't shove 15m of coil in a 1.7L kettle. I would aim for as close to 10m as you can get, and see what size HEX you need. A couple of metres is really not enough.

If you can do this, you will find you will get good ramp rates and good stability.

 

[TheWiggman]

(had this sitting on the screen before Adr_0 replied, in interests of comparison)
For a 120l batch, I'll assume about that in the MT? You'll want a lot of heating power for decent ramps, so if going electric you're looking at some serious draw for a domestic system. On a standard 23l brew this normally corresponds to 15-18l of liquor in the MT for around 3.5-5kg of grain. 2400W is enough power for 1°C/s or thereabouts.
Scaling up, 5 times the volume means 5 times the power for the same rate of temp increase. So if you're looking for good ramp times I would suggest -

• 10kW of heating power
• 5m of coil or greater
• Upgraded pump from the standard 809 or Chugger

With a lot of power you are going to generate a lot of heat if you can't keep the flow up through the coil. The longer the coil the more resistance to flow, but the more exposure to the HEx water so there is more to gain by making the coil longer.
And of course, minimise the liquid in the HERMS vessel.

 

[Adr_0]

TheWiggman raises a good point actually.

If you had 80L of water and 100kg of mash, I guess you would need 3 phase or a 40A circuit.

You could gas boost of course, with a 2—ring or something similar and get away with a smaller element. Have it ticking along and the element provides 'trim' to the temperature. Not foolproof though.

And yes, you might want as much coil as you can get your hands on and a big pump to back it up.