ISO: HERMS Fast Read Thermostat

[scruff311]

I put together a HERMS setup for mashing and have been using the Inkbird Itc-308 for temp control of the mash. My biggest problem with it is that the thermometer is very slow to reach the correct reading, especially when compared to my Thermopen. This results in a 3-6 degree increase in a couple of minutes after the set point was hit and the recirculating pump was shut off.

Does anyone have a recommendation for a higher quality thermostat that will read the temperature much faster than this Inkbird device?

 

[jmark]

Can you provide more detail on how you have your HERMS set up and specifically where you measure the temperature you use to control the heating of the wort? If you keep the HLT controlled to your appropriate temperature you should never get overshoots of mash temp. If you have the probe in the mash itself, you'll never be happy as you'll be chasing your tail trying to hit temperatures.

 

[scruff311]

Can you provide more detail on how you have your HERMS set up and specifically where you measure the temperature you use to control the heating of the wort?

I am using a 15 gallon stainless kettle as a MLT with a stainless thermowell at about the 4.5 gallon mark that extends to pretty much the center of the MLT. The probe for the Inkbird goes in this thermowell. For most batches, this will be sitting in the top 25% or so of the mash.

The MLT outlet goes into a pump which pushes the wort through a 25' copper coil that is sitting in my brew kettle in 160F-180F water (this is ultimately the sparge water). Finally the heated wort returns to the top of my mash. At the end of the mash, the coil bath water (sparge water) is drained into my HLT cooler so that the kettle is free for runoff.

 

[jmark]

Yeah, I think this is your issue... change the measurement so you're measuring the temperature of the brew kettle water. That way your wort will never go above what you have in the BK and it will eventually stabilize at your desired temperature. If you find that the temperature exchange isn't 100% efficient (i.e. the wort returning to the MLT isn't at the same temperature as your BK water temp), then simply set your set point on your BK water that many degrees higher.

 

[Crazyeyes]

Yep, I'll agree withe the rest of of the boys. You need to control the temperature of the water that your Herms coil is setting in and then find the temperature difference needed to keep your mash at the disired temperature. On my system, with a 50' section of 1/2" stainless for the Herms coil, I have about a 14 degree difference between my HTL temperature and my Mash Temperature, so if I want to mash at 150 degrees I need to set my HTL to 164. Generally I'll get about a 7 degree temperature rise coming out of the Herms Coil during recirculation.

 

[scruff311]

Hmm, okay I guess I had it a little backwards then. So do you guys keep recirculating during the entire mash?

Also, I've noticed pretty big temp gradients across the grain bed. I'll usually get say 152 at the top and something like 147 at the bottom. Have you experienced something similar and if so which part of the mash (top, middle, bottom) do you try to keep at your target temp?

 

[jmark]

Yeah... usually recirculate throughout the mash... start off with a bit of a restricted flow (by controlling my valve back into the mash) and after a few minutes start opening it up full throttle.

I don't worry about stratification in the mash since as long as the HLT is kept at the right temperature, the wort returning to the mash will eventually stabilize the entire mash. Keeping a lid on the mash helps and I know some folks use insulation to further help keep temps stable, but I brew indoors and my brew space temperature is relatively constant year round so I don't worry too much about losing temp at all.

 

[day_trippr]

I run my 3V single tier in a very similar manner to jmark - and indoors as well, at least during the cold seasons.
I run a 50' 1/2" hex which I believe helps a lot as I can set the HLT to the desired mash temperature and let it rip.
By the time the wort exits the HEX it's right on the money. Does a pretty decent step as well...

Cheers!

 

[scruff311]

I have about a 14 degree difference between my HTL temperature and my Mash Temperature, so if I want to mash at 150 degrees I need to set my HTL to 164.

What do you use to keep your HLT at a steady temperature? I first tried a thermostat controlled 1000W submersible heater in a 5 gallon cooler but this struggled to keep the temperature above 176F when the pump was on which was giving me a mash temp of 146F (inefficiency due to 25' 3/8" coil I guess). I was thinking about switching to a metal HLT and using a hot plate or induction plate that could be controlled by my thermostat to keep it at 180-182F or so.

 

[jmark]

My HLT is a SS kettle... I actually recirculate water out of it and back in the top using a second pump so that I don't get any stratification in the HLT which might cause the HERMs coil to not work efficiently. The HLT has an element mounted inside and I use a PID to keep the temperature at about 1 degree higher than my mash temp. That's all the offset my HLT needs to keep the mash at the right temp.

I'd strongly recommend checking out http://www.theelectricbrewery.com/ and checking out how Kal has set up his system. Even if you don't build out a system like his, he has his brew day step-by-step that should give you a good idea of how to operate a HERMs style system effectively.

 

[day_trippr]

Propane powered, but I also have a second pump (the one on the right) keeping the hlt stirred while the other pump recirculates the mash.



The same pump sends sparge water through the hex to the mlt when the time comes.
As one may detect from the lines I never run wort through that pump.
The pump on the left does the mash recirculation, lautering to the bk, bk recirculation and finally drives the wort through the pc on the way to the carboys.

The one thing out of all of this I would most highly recommend is going with a 50' 1/2" SS hex. It makes operation easy enough to manage manually for those who just haven't gotten 'round to automation yet (Or fabbing proper heat shields. Gotta get to that)...

Cheers!

 

[Crazyeyes]

My HLT is a 15 gal. kettle with a 5500w element controlled by a Auber Ezboil PID. I've considered recirculating the water in my HLT, but I don't know if it's necessary, because of the convection currents inside the kettle that circulate the hot water from the bottom to the top, you have too remember that the the more hoses, pumps and fittings you add the greater temperature loss through all those things. I'm not saying it's a bad idea, but IMO if your running a lower wattage system, I'd conserve as much heat as possible.

 

[jcav]

I do the same as Jmark and Trippr. I highly recommend the 50' 1/2 inch stainless hex coil in the HLT. I also would recirculate the water in your HLT with a pump the entire time and this will take care of any stratification and your hex will work properly. Also cover the mash tun with a lid and recirculate the mash the entire time. If you have to raise the temp of your HLT a few degrees higher to reach your mash temp, that's no big deal. You will loose some heat in your hoses. Good luck! Here is a shot of mine.

John