How best to HERMS?

[ChrisfromAbby]

I'm considering adding HERMS to my brew system, but it occurs to me that there are two different ways to go -

1) circulate the wort through a heat exchanger inside the HLT
or
2) Circulate water from the HLT through a heat exchanger in the mashtun

The advantage of 1 is that I can use my sparge arm to circulate wort through, but I have a risk of denaturing the enzymes in the wort in the 75C water of the HLT

The advantage of 2 is scorching or denaturing the wort is highly unlikely and I can pretty simply run a line off of my sparge system with a valve to switch between sparging and the heat exchanger, but I'll need to simultaneously recirculate the wort to keep it from having a local hot spot around the heat exchanger.

Is there anything I haven't thought out?

Chris

 

[kevink]

I don't think #2 has any advantages over #1. If you control the temp of your HLT or the wort returning to the MT, you will never, ever overheat.

The worst part about #2 is poor heat transfer from the coil to the mash even if you recirc the mash.

Using #1, you can also very easily switch from recircing wort to sparging. I move two hose ends, but you can also do it with ball valves.

 

[grathan]

I was convinced I needed a herms, but they seem so slow. Gonna try using decoctions for a couple brews to see how that goes instead.

 

[ChrisfromAbby]

I am growing tired of decocting when my step mashes miss the target and am therefore considering HERMS....

 

[grathan]

Interesting. I was thinking of using beersmith calculator to try decocting.

What about a hybrid setup herms/rims using both heat sources?


I think if you put the exchanger inside the mash tun it would make it more challenging to stir out dough balls, though it would be easier to keep sanitary.

 

[Bill_in_VA]

Or option #3: Use a plate chiller. Flow both through it and you can also use after knockout to chill...

 

[dmcman73]

Or option #3: Use a plate chiller. Flow both through it and you can also use after knockout to chill...

Wouldn't a counterflow work better? I was thinking of doing it with the new counterflow I just ordered, I figured that the plate chiller would clog up with the wort coming directly off the MT, I could be wrong.

 

[LandoLincoln]

Cleaning a HERMS coil that sat in your mash tun sounds like a nightmare. I'd much rather go with option 1.

 

[flugelizor]

I have #1.
I think that is true HERMS. The "R" in Herms means you recirculate the mash wort.
A (real or perceived) advantage is clearing the wort while recirculating.
And it sets up a nice grain bed for when it comes time to sparge.

Also, if you go method #2, you will have local hot spots because the mash is so thick the liquid is trapped against the coil. Bad idea.

I would avoid using the sparge arm to recirculate as it would introduce oxygen. I just lay a silicone tube on the surface of the mash, and the returning wort sets up a whirlpool. There are several great clips on youtube.

 

[kevink]

I have #1.
I think that is true HERMS. The "R" in Herms means you recirculate the mash wort.
A (real or perceived) advantage is clearing the wort while recirculating.
And it sets up a nice grain bed for when it comes time to sparge.

He said he would recirc the wort even if he goes with option #2. It still doesn't make it a good idea, though.

 

[steveoatley]

"Also, if you go method #2, you will have local hot spots because the mash is so thick the liquid is trapped against the coil. Bad idea"

Agreed
You would need to be constantly stirring the Mash to beat the hot/cool spots.

I am building a system based on #1

Steve

 

[LakeErieMonster]

This.

I have #1.
I think that is true HERMS. The "R" in Herms means you recirculate the mash wort.
A (real or perceived) advantage is clearing the wort while recirculating.
And it sets up a nice grain bed for when it comes time to sparge.

Also, if you go method #2, you will have local hot spots because the mash is so thick the liquid is trapped against the coil. Bad idea.

You definitely want the exchanger in the HLT. I would never want to clean the herms coil set in the mash either....

 

[kevink]

I doubt anyone in history has ever gone with option #2... There is just no benefit. Only downsides.

 

[BigBlueDog]

Here's an example for executing Option 2:

http://byo.com/stories/issue/item/2799-build-a-heated-mash-tun-projects

 

[kevink]

HaHa, I knew someone would find an example after I posted that. It still doesn't make much sense to me.

 

[grathan]

Doesn't mold build up in coils that obviously will retain liquid? I suppose you could add a cleaning cycle to the front of every brew day, but never having the wort inside the coils would be a definite plus for me. I like the idea of the removable mash coils. WHy would they be hard to clean? The mash tun rinses down quick with a hose, what would make the heated coils any different?

 

[steveoatley]

I pump the sparge water through the coils, into the Mash Tun
Pushing out any wort

Having my HERMS coil inside my Brew Kettle, means that any wort/water left in there is turned to vapor during a 60 minute boil

Then I chill the Brew Kettle by pumping water & PBW through the coil
that cleans out any left over wort.

Steve

 

[Beernik]

When I first thought of building a HERMS I was thinking about option #2. But it seems to me to be a less efficient way of heating the mash and you don't get the benefit of a clearer wort.

 

[trimixdiver1]

Or get a nice shell and tube HE off eBay. I use two pumps, but so far during testing I'm able to maintain +/- 1f. I also have a band heater on my MT, so kinda a RIMS too. I call my system HERHLMIMS.

 

[Yooper]

Cleaning a HERMS coil that sat in your mash tun sounds like a nightmare. I'd much rather go with option 1.

"Also, if you go method #2, you will have local hot spots because the mash is so thick the liquid is trapped against the coil. Bad idea"

Agreed
You would need to be constantly stirring the Mash to beat the hot/cool spots.

I am building a system based on #1

Steve

Agreed! The only thing with having the HEX in the HLT is that you want to recirculate the water in the HLT to avoid localized hot spots. I have a little stirrer and that's it, and my old immersion chiller is the HEX for my HERMS.

 

[brewery_fixer]

Agreed! The only thing with having the HEX in the HLT is that you want to recirculate the water in the HLT to avoid localized hot spots. I have a little stirrer and that's it, and my old immersion chiller is the HEX for my HERMS.

Show us the stirrer, please sir

 

[Yooper]

Show us the stirrer, please sir

You mean me? I mean I'm not exactly "sir" material. But anyway, I've shown it before, but here goes:




The fan is to keep the motor from the stirrer from overheating, and it DOES overheat without the fan. So, the fan cools the motor, and the motor stirs the spoon, and it plugs into my control panel.

Please ignore the dust on it!


On the front of my control panel, it has a switch for "stir":

It's hard to see, but the first switch is for the heat for the HLT, then the PID for the temperature, and then the switch for the stirrer (all in the top row).

That's an old photo, when I had a cooler for an MLT, but I haven't changed the control panel at all.

 

[sandyeggoxj]

I set my HLT to about 3 degrees higher than I want the mash temperature. Based on testing of my system I have found this to be adequate to account for heat loss in the tubing and pump head. My temperatures are controlled by my BCS in PID mode with the dfault PID settings. Works great.

 

[brewery_fixer]

nice, thanks for showing

 

[ChrisfromAbby]

I thought the "hotspots" in the HLT was a practical fallacy? That in most standard sized kettles the heat in water was pretty uniform due to convection currents.

 

[LandoLincoln]

I thought the "hotspots" in the HLT was a practical fallacy? That in most standard sized kettles the heat in water was pretty uniform due to convection currents.

I heat up my strike water in my 19" wide BK and if I just let it sit there, it will get to 152° pretty fast. The temp probe is located on the side bottom of the pot, I think it's a 2" probe. And then I stir the water and then the PID shows a rapid 10-12° drop in temperature. So...no...there's definite hot spots if you don't stir or recirculate.

 

[flugelizor]

+1 hotspots
First couple of batches I recirculated my HLT and the mash temp was 3-4F less than the HLT probe temp.

Last batch I left the HLT still and Mash temp = HLT probe temp for most of the mash.