Where is your thermowell?

Homebrew Talk - Beer, Wine, Mead, & Cider Brewing Discussion Forum

Help Support Homebrew Talk - Beer, Wine, Mead, & Cider Brewing Discussion Forum:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.

The Pol

Well-Known Member
Joined
Feb 12, 2007
Messages
11,390
Reaction score
117
If you are using a march pump for a HERMS system, where do you read your temperature? I would love to use a Love controller, but shouldnt I be reading my temp in the MLT outflow? Say in the tubing itself? When that temp reaches my set temp, my grain bed is the correct temp. Is this what you do?
 
When I began to plan my HERMS I had the same exact thought. However, if you place your thermocouple at the MLT outflow, you will overshoot your grain bed temps. I actually place my thermocouple at the MLT inflow. I have found thru trial and error that if I set my controller at 2F above my desired mash temp, that I will hit my mash temps dead on every time (in my system).
 
how will you overshoot your temps if your HERMS heat exchanger is set to your set mash temp? If my water is 152F... I wont overshoot, and when my outlet wort reaches 152F, then my mash is heated thoroughly... right? Heating my keggle and my heat exchanger to the proper temp is my only reason for buying an LP gas solenoid to turn on and off my burner, to maintain that water temp.
 
The Pol said:
how will you overshoot your temps if your HERMS heat exchanger is set to your set mash temp? If my water is 152F... I wont overshoot, and when my outlet wort reaches 152F, then my mash is heated thoroughly... right? Heating my keggle and my heat exchanger to the proper temp is my only reason for buying an LP gas solenoid to turn on and off my burner, to maintain that water temp.
I found that this method takes roughly FOREVER when doing a HERMS step mash. I usually heated the water in the heat exchanger to around 160-170 for most steps, then increased to 180 for the mash out. My efficiency was usually pretty good, but I saw a marked increase when I went to steam infusion.
 
So, let me get this accurate. I OVERHEAT my exchanger and overshoot my temps going into the mash to heat up the mash more quickly. SO the top of my mash is 165F and the bottom is 152F. Wouldnt this cause much more severe stratification in my mash? Because if I implement some sort of strirring mechanism to eliminate the stratification, I am now eliminating one of the purposes to using a HERMS.... clearer wort...
 
Hello, can anyone explain to me how I can avoid serious heat stratification in my mash if I overshoot my mash temp in my HERMS oulet temp??
 
IMHO, it all depends on your set-up. I measure the temp as it exits the HERMS coil. However, I don't use my HLT for the HERMS, I have a dedicated vessel that houses the HERMS coil. I use a small round cooler that maybe holds a few gallons. I then use a bucket heater to heat the water. So basically the wort exiting the coil is the temperature I want the mash.
 
The Pol said:
I am now eliminating one of the purposes to using a HERMS.... clearer wort...
I always stirred when stepping up the temp. Between steps, I would occasionally recirculate through the heat exchanger to maintain the temp, avoiding any stirring at that point. I never stirred during the mash out, and the wort was amazingly clear due to the long period of recirculation at the end of the mash.
 
If you place your thermocouple at the heat exchange coil exit (or MLT inlet), your wort will never exceed the "dialed in" temperature. Your "dialed in" temp will need to be slightly higher than your desired grain bed temp; how much higher will depend on the recirculation flow rate and heat loss from your MLT.
I recirculate constantly and I only stir at mash in. My heat exchange coil is in my HLT but I have two 4500 watt, 240 vac heating elements in my HLT so I can ramp up temps pretty quickly. Recirculation flow rate has been my rate limiting factor for ramping up mash temperatures.
 
I think you've just touched on the dilemma with HERMS/RIMS/Direct-fire solutions. Maintaining consistent temps throughout the mash and temp steps do not have the same goals. When you want to step the temps, then the wort has to be overheated at least a little. The closer you keep the wort to your target step temp the longer your step is going to take. The faster you want to heat your wort, the more you have to overheat the wort, the more stratification you have, and the higher the chance for overshooting your step.

I haven't studied steam, but it may side-step this problem to a "degree". (pardon the pun ;))

Anyway, I don't think there's a perfect solution. You gotta try it, play with it, and live with it or change it.
 
Does anyone with Direct Fire Mash know how accurate the thermowell on the MLT exit is vis-a-vis grain bed temperature? I would think that CRDFM would be the most accurate way of insuring a consistent bed temperature.

Also, has it been confirmed that in a HERMS setup, there is no good way to get a precise measurement of grain bed temperature into your controller? It seems that there has to be some on the fly adjustments if done on coil exit, and severe stratification if done on MLT exit (assuming you are using hotter water than mash).

Thanks
KD
 
I haven't, but I think having a temp reading on both would be very nice. Mine is installed in the lower part of the grain bed. I have to be careful when direct-firing the mash not to overshoot my target because it takes a while for the heated wort to work its way down to my probe.
 
Well, after speaking to an experienced HERMSer at my LHBC, I have decided that termowell in the mash is the best location. He has a bypass solenoid that recirculates the wort when the exchanger coil kicks off. I have two pumps, so I can do the same thing basically. As long as you are recirculating, I suppose the center of the grain bed would be the best place for a HERMS probe.
 
Hey korndog, im not planning on adding the heat exchanger to my single tier, but i would curious as to how and where you are placing it to make it a HERMS. Any pics yet?

I purchased two short thermowells that i am putting in the output of the kettles; HLT and MT that will house the probes from the Love switches.

I guess in my mind if I'm recirculating, albeit slowly, the output temp isnt going to vary from the entirety of the mash by much at all..if any. And when i go to sparge, the output temp is the temp going into my brew kettle, so thats the most accurate...again..in my mind. Especially in a direct fire. I dont see how the grain bed is going to to hotter when it is further away from the heat source than the probe measuring the temp.
 
MNBugeater said:
Hey korndog, im not planning on adding the heat exchanger to my single tier, but i would curious as to how and where you are placing it to make it a HERMS. Any pics yet?

I purchased two short thermowells that i am putting in the output of the kettles; HLT and MT that will house the probes from the Love switches.

I guess in my mind if I'm recirculating, albeit slowly, the output temp isnt going to vary from the entirety of the mash by much at all..if any. And when i go to sparge, the output temp is the temp going into my brew kettle, so thats the most accurate...again..in my mind. Especially in a direct fire. I dont see how the grain bed is going to to hotter when it is further away from the heat source than the probe measuring the temp.

no pics yet. I am planning to install a convoluted coil to the HLT lid, and another port for recirculation. When the controller kicks on, it would pump the wort through the coil and back into the MLT. Since i would like to have wort recirculating while the exchanger is idle, I am thinking about installing a 3 way solenoid valve that would divert to the appropriate hose for recirculation.

As to DFM;

If I am thinking this through correctly, you will be recirculating your wort at the strike temperature initially. Once it dips below your set point, your valve will kick on. At this point, your grain bed should be pretty consistent as to temperature. I would think the water in the deadspace would heat up rather quickly, turning off your burner prior to heating your entire mash to set point. It would then recycle often until you hit your temp, which should take a bit longer to ramp. Many people do it that way for HERMS and DFM, concerned with overheating. I'm not sure what's best really, but am pretty sure that with HERMS, I will get more consistent grainbed temps with the probe in the mash while recirculating.
 
Upon further research, i will have to use two two way valves. I can't find suitable three ways with 0 psi rating. The setup will be something like this on Jackie Boy brewery (Nate). The output of the pump feeds the tee between the valves. One valve is connected to the NO terminal and the other to the NC terminal of the controller I believe. I am still planning to use hoses with QD's however.

tubing.jpg
 
korndog said:
Does anyone with Direct Fire Mash know how accurate the thermowell on the MLT exit is vis-a-vis grain bed temperature? I would think that CRDFM would be the most accurate way of insuring a consistent bed temperature.

Also, has it been confirmed that in a HERMS setup, there is no good way to get a precise measurement of grain bed temperature into your controller? It seems that there has to be some on the fly adjustments if done on coil exit, and severe stratification if done on MLT exit (assuming you are using hotter water than mash).

Thanks
KD

I can only comment on the time it takes to ramp up temps. I don't use a thermowell, but I do occasionally do a direct fire. It took me approx 15 mins to make a 10 degree jump (acceptable IMHO), and I was going very modestly on my flame. I noticed absolutely NO burnt/off flavors I could attribute to flaming the bottom of the MLT....and I actually tasted the wort several times after it was heated and returned to the top of the mash.

BEGIN RANT: Those were all good beers... BUT! I realized....I had made just as good and better beers with a single step infusion and no mash-out! Let's face it, guys: The grains we buy are so well modified, that batch sparging at a single temp will put you in the 80's for efficiency! The only reason why we do temperature steps is to activate different enzymes to create more sugars and/or affect mouthfeel....and the truth is that you can activate several different enzymes at a temperature that happens to fall within each respective enzyme's range. 150F is where B-Amylase stops and 154F is where A-Amylase begins. Hit your mash at 152F and you'll still be reaping the benefits of both, as these ranges are vague indicators of when the enzyme will become active. Most people will NEVER do a B-Glucanase rest at 95-113F in their entire homebrewing career, so the idea of temp stepping (except for decoction) is kind of a waste of time. HERMS/RIMS/Etc. are kind of just gadgets that will take up more of your brew day but may or may not make beer that is any different from the next guys. RANT OFF
 
rig_setup_009.jpg


the probe sits right in the male side of the QD. So its getting the temp reading as soon as it comes out of the MT and HLT
 
rig_setup_009.jpg


the probe sits right in the male side of the QD. So its getting the temp reading as soon as it comes out of the MT and HLT

Chimone--

Have you used this setup yet? I brewed with my stand for the first time this past weekend. I have VERY similar T fittings with the thermowell quite a distance from the exiting mash. I noticed the thermometer I have in the mash tun differed quite a bit from the probe temp in the thermowell.

I did have them calibrated to each other when I started and noticed that the temp exiting was lower than the mash temps. I dont have an answer as to why other than the ambient temperature could have been lowering the temp readings. The LOVE switch probes arent the quickest to respond.

I going with a different design this weekend so I'll report back.
 
Chimone--

Have you used this setup yet?


No but I will soon. Im not expecting the temps to match up with my very accurate glass lab thermometer Ive always used, but I will be able to tell very quickly where I am and adjust accordingly. If I need to bump up the LOVE controllers two degrees or whatever to compensate well so be it.

I figure after a few runs with nothing but water I will know where I stand with them. On a side note, the thermowells were rather long, and I had to cut them down and re weld them so they would fit in the T fitting. Not sure how that is going to come into play yet either.
 
No but I will soon. Im not expecting the temps to match up with my very accurate glass lab thermometer Ive always used, but I will be able to tell very quickly where I am and adjust accordingly. If I need to bump up the LOVE controllers two degrees or whatever to compensate well so be it.

More than likely, you will have to lower the LOVE setting a few degrees. I had my inaugural run yesterday and found that my thermowell temp was lower than actual mash temps and I was overshooting my Mash temp cause the external thermowell/couple location wasn't accurately reading the mash.

On a side note, the thermowells were rather long, and I had to cut them down and re weld them so they would fit in the T fitting. Not sure how that is going to come into play yet either.

I had this problem too, and ended up created an extension from my "Tee" fitting that would accommodate my thermowell. I am still trying to figure out the best way to remedy this.

My first idea was to remove the bi-metal Brewmometer that is in the side of my mash tun and just place my thermowell in there. That would put my probe right in the middle of the mash and in theory should provide the best reading.

I plan on brewing again this weekend after some design changes and Ill keep you posted.
 
i guess its the same with every rig you may have throughout your brewing career. You need to learn your rig inside and out. And just brew alot to get to the point where you just know where you're temps are going to be.

Keep me posted as from the sound of it Im right behind you. I should be doing test runs this coming weekend.
 
I cut my thermowell's and used JB Weld to seal them back up. I am considering a weldless thermowell directly in the mash as well.

KD
 
I am considering a weldless thermowell directly in the mash as well.

KD

I will be testing this on Saturday. I will let you know the results.
Here is the thermowell(s)I ended up buying. I have a 9" one in the lids of the MT and the HLT. The HLT is perfect. The MT is a little short for my 15G. I had a grain bill of just less than 19 lbs and the thermowell just barely in the top of the mash. I considered getting a 12" for the lid, but instead I'm opting for the sidewall thermowell.

I also have a couple 4" wells that are 1'2" NPT, I am going to remove the brewmometer in my Blichmann and put this in its place and try a mash that way. The location is about perfect. It will stick in the middle of the mash about 3.5" -4" from the side of the MT.

This was the solution I came up with after yesterday's session. Either that, or just brew larger batches so I have more grist and my lid placed thermowell will then be in the heart of the Mash. I bought a 15G MT and 20G Boil kettle for a 10G batch based on the fact that I had a 14G boil kettle and routinely had near boil overs for 10G batches.

I really think though with 15GMT and 20G BK, I could do 15G batches just fine. Not only would my lid thermowell reach into the mash, but I'd get more beer. Is that not just the perfect solution ?
 
So I've had two batches now on the new brew stand.

Some findings on my thermowells, thermometers, and temp readings.

I mashed at 152 last night and In my mash tun I discovered three different temperature readings.

I had a thermowell on the exiting wort during a recirculation, a bi-metal Brewmometer mid-kettle about mid-grain bed height, and a 9" lid thermowell that reached about 1.5-2" into the top of the mash. Maybe only an inch inthe actual grain.

So right at mash in, I noticed about a 13-14 degree difference form exiting wort to top of the grain bed, with the brewmometer somewhere in the middle. Sorta made sense, hottest at the bottom where the dip tub was pulling wort from the bottom as its getting direct fired.

As the recirc went on, the lid thermowell and the exiting wort thermowell started to equalize. Once things stablized, I found the perfect location to take my temps for my LOVE controller to manage temps.

The existing wort read 154-156, the lid thermowell read 150-152. These would fluctated based on if the burner was on or not.

But the bi metal brewmometer directly in the middle of the mash read 150-152 nearly the whole time. I am going to replace the brewomemter with the thermowell and use that location for the LOVE controller probe to control temperatures. I feel this is the best location as the desired mash temp is the temperature of the grain to produce the conversation of starch to sugar.

I think I'm getting a feel for this new system, but will have to brew again on Saturday to make sure. :D

I learn something new each time and hope to have this thing dialed in shortly.
Now i need to make a hop bag, I struggle with the hops clogging my brew screen on the Boilermaker kettle.
 
So I've had two batches now on the new brew stand.

Some findings on my thermowells, thermometers, and temp readings.

I mashed at 152 last night and In my mash tun I discovered three different temperature readings.

I had a thermowell on the exiting wort during a recirculation, a bi-metal Brewmometer mid-kettle about mid-grain bed height, and a 9" lid thermowell that reached about 1.5-2" into the top of the mash. Maybe only an inch inthe actual grain.

So right at mash in, I noticed about a 13-14 degree difference form exiting wort to top of the grain bed, with the brewmometer somewhere in the middle. Sorta made sense, hottest at the bottom where the dip tub was pulling wort from the bottom as its getting direct fired.

As the recirc went on, the lid thermowell and the exiting wort thermowell started to equalize. Once things stablized, I found the perfect location to take my temps for my LOVE controller to manage temps.

The existing wort read 154-156, the lid thermowell read 150-152. These would fluctated based on if the burner was on or not.

But the bi metal brewmometer directly in the middle of the mash read 150-152 nearly the whole time. I am going to replace the brewomemter with the thermowell and use that location for the LOVE controller probe to control temperatures. I feel this is the best location as the desired mash temp is the temperature of the grain to produce the conversation of starch to sugar.

I think I'm getting a feel for this new system, but will have to brew again on Saturday to make sure. :D

I learn something new each time and hope to have this thing dialed in shortly.
Now i need to make a hop bag, I struggle with the hops clogging my brew screen on the Boilermaker kettle.

Thanks Warren. I have been going back and forth with this. The guy who built our brew club system feels pretty strongly that the probe should be in the mash as you describe for a few reasons. This also allows you to set up your pumps on "Auto" if you don't want to continuously recirculate while the burner is off.

KD
 
Thanks Warren. I have been going back and forth with this. The guy who built our brew club system feels pretty strongly that the probe should be in the mash as you describe for a few reasons. This also allows you to set up your pumps on "Auto" if you don't want to continuously recirculate while the burner is off.

KD

Ironic you mention the pumps on auto idea. As soon as I realized I was going to move the probe to the middle of the mash, it hit me that if i do so rewiring I could have the pump stop when the burner does. And likewise, turn on when the burner does. NO need to conitnue recircing if the fire isnt on...
 
Ironic you mention the pumps on auto idea. As soon as I realized I was going to move the probe to the middle of the mash, it hit me that if i do so rewiring I could have the pump stop when the burner does. And likewise, turn on when the burner does. NO need to conitnue recircing if the fire isnt on...

Yep, I already have the three position switches mounted in the panel. I still want manual control of the pump(s).
 
I have a slightly different set-up than you guys, I'm using electric heating in a seperate heat exchanger. My controller probe is after the heat exchanger so I know what temp is being dumped on top of the mash. After doing this I realized I really have no idea what my mash temp is when doing a step, all I can see is that the heat exchanger is putting out wort at my set temp. I added a compression fitting with a probe for an electronic thermostat to the output of my mash tun and I find that they do equalize about 10 minutes after mash in.

The only problem with putting the controller probe mid mash is that your burner could overheat the wort before it gets to the probe.

Let's say you get your system set up, you mash in and things are chugging along at 152. 10 minutes in to the mash, the burner kicks on to add some heat and blows some carmalized sugar or rust out of some of the holes and suddenly is putting out a bit more heat. If it is heating faster than your pump is pumping, it will quickly get the wort over170 before it gets to the probe to shut the burner off.

I know this is theoretical, but the best way to insure you never overheat your mash is by monitoring the outlet of the mash tun.

My first try at my electric experiment, I had the controller at the output. Everything was fine until the system called for more heat. The heating element was able to heat much faster than the wort was moving through the system. When the probe finally reached set temp, the mash temp continued to rise to 13 degrees over my set temp due to the much hotter wort being dumped on top.

Anyway, that's been my experience so far.

Linc
 
i don't really have much of a problem leaving the pumps on. It's not going to hurt it, and have you seen how clear your runnings get after 20 minutes or so? Holy Cow!
 
That was my thought to is the grain bed makes a great filter with 60 minutes of recirc, I'm not sure how much less filtering there might not be if the pumps shut off occasionally. Something tells me the difference might be minimal.

Linc
 
Let's say you get your system set up, you mash in and things are chugging along at 152. 10 minutes in to the mash, the burner kicks on to add some heat and blows some carmalized sugar or rust out of some of the holes and suddenly is putting out a bit more heat. If it is heating faster than your pump is pumping, it will quickly get the wort over170 before it gets to the probe to shut the burner off.....

Linc

Yeah, this is definitely the weak link in the process. I'm not sure how much wort per minute I can pump through the dip tube, but the pump is rated 7 GPM, so at full speed it wouldn't take long to get to the probe. I think keeping the flame throttled way back would be key to preventing big overshoots.
 
The only problem with putting the controller probe mid mash is that your burner could overheat the wort before it gets to the probe.


Linc

I had that exact concern, which is why I had three separate locations for readings. After seeing that the middle of the mash was the most stable and consistent even when the burner was on and the exiting wort was 4-5 degrees hotter than the middle of the mash, i decided that was the best place to take the reading. As opposed to the top or bottom which had the biggest variance. I figure my burner MIGHT fire up only 1-2 times during a mash. The middle mash temp reading only differing 1-2 degrees from my exiting wort also told me that my pump was doing a fine job of recirculating efficiently enough not to allow scorching to occur on the bottom.

I will have more results after Saturday when I brew my 3rd batch in 6 days. I really think brewing that frequently on a new system gets it really dialed in, cause I can remember batch to batch the nuances and make the changes. Im confident that Ill have this damn close if not exactly how I want it after this weekend....Then I can REALLY start making some beer. I'm gonna need some more carboys...or maybe the nice 15 G Stainless Conical... :D
 
Ironic you mention the pumps on auto idea. As soon as I realized I was going to move the probe to the middle of the mash, it hit me that if i do so rewiring I could have the pump stop when the burner does. And likewise, turn on when the burner does. NO need to conitnue recircing if the fire isnt on...

Can you give me a rundown on how I would wire the on/off/on switches? I'm working on it now, but am not sure.
 
Can you give me a rundown on how I would wire the on/off/on switches? I'm working on it now, but am not sure.


pretty straight forward

switch will be on the black (hot) wire. Just run it inline with whatever you want switched on/off. It will either allow the circuit to be open or closed turning it on or off

However.....if you are talking solenoid switches, well the LOVE temp controllers provides the power for those, not the bus directly. Pin 11 I believe is the one you run to the ASCO. Simply take the output from pin 11 and put a switch inline.
 
pretty straight forward

switch will be on the black (hot) wire. Just run it inline with whatever you want switched on/off. It will either allow the circuit to be open or closed turning it on or off

However.....if you are talking solenoid switches, well the LOVE temp controllers provides the power for those, not the bus directly. Pin 11 I believe is the one you run to the ASCO. Simply take the output from pin 11 and put a switch inline.

Thanks for the help. Makes sense now.
 
Ironic you mention the pumps on auto idea. As soon as I realized I was going to move the probe to the middle of the mash, it hit me that if i do so rewiring I could have the pump stop when the burner does. And likewise, turn on when the burner does. NO need to conitnue recircing if the fire isnt on...

hopefully I will test this theory out this weekend, but......

wouldn't leaving the pump on without the fire going allow your grain bed to obtain a more consistent temp?
 
Back
Top