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A Herms Question - Wort Return Temp Or Grain Bed Temp

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Kingbrownbrewing

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Since getting my HERMS going with Nevs coil, I have noticed that the reading for my wort return and the reading of my grain bed differ by about 4 degrees.

So when the returning wort is at 69, the grain bed is only at 65. (Both thermometers are calibrated and digital).

Should I amp the HERMS up by 4 degrees to get the grainbed to 69 and have the wort return running at 73 or should I rely on the temperature of the wort return.

What do you guys do?
 

mxd

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Since getting my HERMS going with Nevs coil, I have noticed that the reading for my wort return and the reading of my grain bed differ by about 4 degrees.

So when the returning wort is at 69, the grain bed is only at 65. (Both thermometers are calibrated and digital).

Should I amp the HERMS up by 4 degrees to get the grainbed to 69 and have the wort return running at 73 or should I rely on the temperature of the wort return.

What do you guys do?
I take the reading on the return wort at the MLT, mine is generally 2 degrees cooler in the grain bed, I just set my PID mash temp and try not to look at grain bed
 

razz

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If the equipment is calibrated then I would maintain the desired mash temp at the HERMS KBB. The enzymes , in the liquor, run through the HERMS so it's there that you want to keep the mash temp you want. The grain bed will eventually catch up but is dependent on flow rate, tun insulation etc.
 

Yob

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Not that I have a great deal of experience with it having only done 1 recirc brew.. but I was using the probe in the grain bed..

It seemed to make sense to me that the temp in the HEX would rise or fall to suit the grain bed which is ultimately what I wanted to control..

I mashed in at 66 and set the HEX to 65 and moved the probe a few times to various places in the bed throughout the mash..

reading through THIS it seems many people do use the probe at the wort return.

Personally I need to do a bit of work on the return hose to get a more even return to the grain and will follow this with interest.

Yob
 

hsb

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You want the probe to be at the hottest point, otherwise you are overheating the liquor through the HERMS and in effect mashing higher than you intend. Definitely the HERMS outlet, grainbed temp doesn't matter, just the liquid itself.

Ideally your HEX and Tun will gradually equalize anyway, or close to.
 

QldKev

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You want the probe to be at the hottest point, otherwise you are overheating the liquor through the HERMS and in effect mashing higher than you intend. Definitely the HERMS outlet, grainbed temp doesn't matter, just the liquid itself.

Ideally your HEX and Tun will gradually equalize anyway, or close to.

+1

The grain bed will always lag behind. In my system I can measure a difference between the top and bottom of the grain bed by a few degrees. This is why you want the highest possible flow without sucking down the grain bed and getting a stuck mash, to try and get the best mixing of the temps to equalise it out.

QldKev
 

Screwtop

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You want the probe to be at the hottest point, otherwise you are overheating the liquor through the HERMS and in effect mashing higher than you intend. Definitely the HERMS outlet, grainbed temp doesn't matter, just the liquid itself.

Ideally your HEX and Tun will gradually equalize anyway, or close to.

+1

The grain bed will always lag behind. In my system I can measure a difference between the top and bottom of the grain bed by a few degrees. This is why you want the highest possible flow without sucking down the grain bed and getting a stuck mash, to try and get the best mixing of the temps to equalise it out.

QldKev

Good advice here....

Screwy
 

Kingbrownbrewing

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Thanks guys, I thought that might be the case, and that is how I measure it at the moment, I was just wondering how everyone else does it.

Cheers for the info.
 

hughman666

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My sysem has a steady 1-2 inches of wort on top of the grain bed throughout the mash and i have my probe sitting in this liquid. I guess that's a combination of both grainbed and wort return, seems to work though...
 

QldKev

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My sysem has a steady 1-2 inches of wort on top of the grain bed throughout the mash and i have my probe sitting in this liquid. I guess that's a combination of both grainbed and wort return, seems to work though...

as long as you are happy to not have read any of the good info above, go for it
 

hughman666

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Um I actually have read the above info. If my probe is sitting in the 1-2 inches of liquor above the mash, this is actually sitting in the wort return liquid, just not as it shooting through the herms pipe.

I dont see your point...

as long as you are happy to not have read any of the good info above, go for it
 

NickB

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Hugh - its because the enzymes that do the 'heavy lifting' of the conversion are in the liquid part of the mash. By measuring the wort sitting on top of the grain bed, you're likely heating the liquid through the heat exchanger higher than it needs to be (as you're losing temp between the return point and the overall temp of the liquid in the mash tun), and in turn, likely denaturing the very enzymes you're expecting to convert your mash.

The liquid part (at the hottest point - the outlet of the heat exchanger) is where the ideal point is for measuring your return temps is.

It works for countless HERMs and RIMs brewers, so it should work for you and others.

Cheers
 

hughman666

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Yeah I understand what you and the others are saying. I guess because I'm not using a traditional HERMS setup it's a bit different on my rig. I've measured the temp at the return outlet and the temp in the above-mash liquid and they're bang on the same (ie there's only a couple of inches distance between the outlet and the mash liquid)...

I can see how it would affect an external HERMS setup though...

Hugh - its because the enzymes that do the 'heavy lifting' of the conversion are in the liquid part of the mash. By measuring the wort sitting on top of the grain bed, you're likely heating the liquid through the heat exchanger higher than it needs to be (as you're losing temp between the return point and the overall temp of the liquid in the mash tun), and in turn, likely denaturing the very enzymes you're expecting to convert your mash.

The liquid part (at the hottest point - the outlet of the heat exchanger) is where the ideal point is for measuring your return temps is.

It works for countless HERMs and RIMs brewers, so it should work for you and others.

Cheers
 

bignath

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nick,

as per the setup in my signature (single vessel recirculating biab)....

I have two points of measuring temp. One is inside a thermowell sitting in the mash which is connected to the stc, which is obviously the thermo that controls whether it adds heat or not.
The other is a dial thermo mounted under the vessel. This thermo is reading the wort as it's being pulled out of the vessel from inbetween two kettle elements. The thermo is probably 3 inches away from the level of the elements.

From that thermo (dial) it goes to a pump and then through some hose and then back to the mash via a return tube mounted in the lid. this return tube, returns the wort within an inch from the temp probe in the thermowell.

Which one should i be paying closer attention to? Only brewed on it once (last weekend) but there was a small discrepancy between the two. Much less differential when i did the wet run, but when there's actually grain involved, the differential is greater - which i fully expected.

The wort probably has just under a metre of hose to travel through before it get's back to the mash.
 

NickB

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Whatever has the higher liquid temp IMHO.

The enzymes live there so are more important than the grain just temp in the mash.


All IMHO though. Go with what works for your system!
 

bignath

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thanks nick.
 

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