HERMS Control Question

[at3brew9]

I'm looking to get some feedback from those of you who run a HERMS system. My system has evolved over the years. In the current design, I use one pump to circulate the MLT wort through one side of my CFC and another pump to circulate hot water from my HLT through the other side of the CFC to maintain temps and do step mashes. Unlike Kal's set up and most of those that I've seen on here, however, my system has two solenoid valves. If heat is required, the valves open to a path through the CFC and if the temp is okay, the valves change so that the wort recirculates back to the top of the MLT without heating. This allows me to keep my HLT at sparge temperatures (say 175-180), instead of mash temps or a bit above.

Most systems on here seem to always recirc through the HLT either via an immersion coil or CFC and don't use any solenoid valves. Is there an advantage to that approach? I would think it would take quite a bit longer to do step mashes if you have to heat the entire HLT to the next temp. However, the system would be a good bit simpler.

I've been using simple deadband control for heating and valve switching, but am finding that I seem to overshoot the first rest temperature most brew days. I'd like to hear everyone's thoughts on the best method of control.

Thx!

 

[orangehero]

You're rapidly denaturing the amylase in the wort that gets heated to over 170°F.

 

[alien]

https://www.homebrewtalk.com/f51/herms-vs-counterflow-herms-349332/

The bursts of flow required to keep the wort hot should be pretty short, the question is whether the wort is mixing well enough to keep the temperature even. If the heated portion of the wort is hot enough for long enough the enzymes will denature as the man says.

The advantage is quicker ramp times but that's not much of an issue for most people.

 

[MadGus]

You've got a single coil instead of two (one herms and one IC/CFC/plate). I thought about doing this on my build, but didn't want to risk denaturing and didn't need the ability to ramp fast. I typically do a one temp mash though.

 

[alien]

Yes only one coil, but maybe a more expensive one than people typically use for a CFC (might not want a rubber hose on the outside).

In many ways it makes a lot of sense. I have only really heard of people toying with the idea though.

 

[at3brew9]

Well I searched the archives and found a bunch of discussion from 2009 on this topic. No one seems to have a definite answer on whether running the amylase enzymes through a heat exchanger and exposing them to 160+ degree temps for a short amount of time will denature them. The amount of time at the higher temps required to denature some or all of the enzymes seems to still be unknown. The Pol noted that he saw definite temp stratification in the mash during the temp steps and I definitely agree. My next session, I'll set the valves so that the wort is always flowing through the heat exchanger and use the HLT temp + 2-3 degrees for doing steps. I have a 5500W element fixed in the HLT and (2) 2000W heat sticks that I can add, so it should be able to manage fairly quick raises.

My CFC is the Chillus Convolutus from More Beer and is pretty efficient. I have both the HLT and CFC somewhat insulated with the Reflectix insulation.

 

[audger]

No one seems to have a definite answer on whether running the amylase enzymes through a heat exchanger and exposing them to 160+ degree temps for a short amount of time will denature them

maybe this will clarify it; yes the enzymes are denatured when they are exposed to high temperatures...

it happens to each individual enzyme almost immediately when that particular enzyme molecule reaches a certain temperature. so pretty much the entire volume of wort in the heat exchanger when the valve icloses is denatured of all enzymes. whether or not this amount of wort matters to the overall brew is variable, but then you introduce more problems when you open the valve and expose the top of the grain bed to wort hot enough to denature more enzymes.

this is why your method is not more common.

 

[alien]

Chillus convulutus is ideal for this.

No really committed brewer has really had a go with this idea and figured out exactly what it takes to get good results. I am sure the idea will work, it will just needs a good brewer to experiment a little and get it right.