Single PID / Pump employment

So if you have read my other threads here, you know where I am in the rebuild process.

Main project R%D is the eHERMS control Box. Understanding that a 2 PID setup would be ideal, I would like to discuss a single PID, single element, 2 pump set up.

I have this....Boil Kettle Control

My question is this;
A. do I set the wort to recirq continually, and the pid controls the temp of the HLT?

B. Set the PID to just recrq the wort at temp drop?

C. I know the PID needs to moniter the mash temp, so how do I set the HLT water temp?

I plane on using mt 2nd pump to recirq the HLT water to maintain even temp throughout.

Just need a little help "seeing" the process i guess.

Thx

You should be continuously recirculating.

thargrav said:

You should be continuously recirculating.

Click to expand...

I kinda figured this, so how do i affect change in the system?

So I use a temp probe at the exit of the herms coil the mash, to cycle the element in the HLT I assume. Then is my set point is the Mash temp I need to hit, other than on or off how to i keep the water in the HLT in the taret range?

I am sure it is simple, i just cant see it....

Tim

when i get a second pump and third pid, i'll modify my plan. however, until then i plan to take the temp as it leaves my herms coil. since the temp i want will be directly influenced by the element in the hlt, i'll affect the change there.

MX1 said:

I kinda figured this, so how do i affect change in the system?

So I use a temp probe at the exit of the herms coil the mash, to cycle the element in the HLT I assume. Then is my set point is the Mash temp I need to hit, other than on or off how to i keep the water in the HLT in the taret range?

I am sure it is simple, i just cant see it....

Tim

Click to expand...

I have RIMS, not HERMS & my sensor is at the output of my RIMS tube. I'd have to assume the same for HERMS - maybe someone who has an electric HERMS will comment.

So I have it set up where the PID monitors the temperature of the water in the HLT and maintains that. One pump recirculates the wort through the HERMS coil, the second pump recirculates the water in the HLT. I do monitor the temperature at the inlet to the HERMS coil, but just for my situational awareness.

You could definitely measure the temperature of the wort, and use that to fire the element in the HLT. My suggestion would be to have it measure the temperature at the inlet to the coil (or the outlet from your MLT). Here's why - you're not concerned about the temperature of the small amount of wort exiting the HERMS coil - you're concerned about the overall temperature of the grain bed and the wort in the MLT, a much larger volume. Measuring the temperature at the outlet of the MLT will give you the overall temperature of the mash, given that the wort will have difused through the grain and the temperatures will have stabilized. The temperature of the wort exiting the HERMS coil will be much higher than that.

So, if I were you and had a single PID, I'd measure the temperature of the wort as it exits the MLT and use that to control the temperature of the HLT. Make sure to run the auto-tune because you could suffer some serious lag and ramping on a setup like that.

-Kevin

BadNewsBrewery said:

You could definitely measure the temperature of the wort, and use that to fire the element in the HLT. My suggestion would be to have it measure the temperature at the inlet to the coil (or the outlet from your MLT). Here's why - you're not concerned about the temperature of the small amount of wort exiting the HERMS coil - you're concerned about the overall temperature of the grain bed and the wort in the MLT, a much larger volume. Measuring the temperature at the outlet of the MLT will give you the overall temperature of the mash, given that the wort will have difused through the grain and the temperatures will have stabilized. The temperature of the wort exiting the HERMS coil will be much higher than that.

Click to expand...

I do HERMS, and I measure at the output of the coil.

When I was building my system and trying to decide where to put the probe, I came on there and posted a poll to see what people use and why. The overwhelming response was that the output of the coil was the way to go. (in fact, many people had originally had their probes in other locations and ultimately MOVED them to the coil output for better behavior.)

The reasoning was, ironically, the same reasoning you used, but in reverse.

If you are measuring at the inlet to the coil and your mash is too cool, the heat in the HLT is going to turn on, but it will stay on until it starts to detect "at temp" wort entering the coil. When that finally happens, you potentially have a lot of very hot water in the HLT and wort coming out of the coil (and at the top of your MLT) that is way over your desired temp.

By measuring at the output of the coil, you are ensuring that the wort that goes back into the MLT is never going to be over your set-temp. The mash holds temps pretty well, so you will settle on your set temp pretty easily.

Other internet research at the time I was building turned up a few places that were suggested to never use, and the inlet to the coil (or outlet of the MLT) was the top one that was suggested to avoid because of temp over shoots.

Anyway... just my $0.02. I do measure at coil output and when I was first using it, I had several thermometers in place. One at the bottom of the MLT, one in the middle of the grain bed, and then the one at the coil output. The variation between these three probes was never more than 1*F.

Interesting logic... I think it would take longer for the mash to get up to temperature measuring at the outlet, but also reduce the risk of overshoot. Come to think of it, if you assume a near 100% efficient transfer of a 50' SS coil in the HLT with 10 or so gallons of water in it, then the output temperature of the HEX would be the same as the temperature of the water in the HLT which is what I measure so I guess I'm doing it the same as you.

I think the Kal setup (which I copied) is honestly the best of both worlds. I have learned that I can set my HLT (and thus wort output from the HEX) temp about 10* above my target temperature, and then start to ramp that temperature down to my target temperature, and I'll see a much faster change in the mash temperature overall. I'm just curious if the 'fuzzy logic' feature of the PID could do all this for us by measuring at the MLT output - ramp nice and fast, and then slow down to get to your ideal temperature... If it worked without overshoot, it would be a much faster heating operation than measuring at the HEX outlet.

BadNewsBrewery said:

if you assume a near 100% efficient transfer of a 50' SS coil in the HLT with 10 or so gallons of water in it, then the output temperature of the HEX would be the same as the temperature of the water in the HLT which is what I measure so I guess I'm doing it the same as you.

Click to expand...

Right. If the heat transfer was perfect, coil output and HLT contents would be the same.

I have only 10' of 1/2" OD copper for my coil, but I pump at a relatively slow rate compared to what my pump can actually do, so heat transfer should be pretty good.

But, I honestly have no idea what temp my HLT sits at when I am mashing. It's probably a couple of degrees warmer, but I've never measured it. I am not particularly concerned with what temp the HLT is and am just interested in the temp of my mash.

I will be using 50ft od 1/2 ss for my coil.

So end state, measure at HEX outlet, let the MLT run at whatever temp it needs to to maintainthe mash temp.

I'm planning my system now and I was intending to go the route of Walker. That seems like the most logical in my head, but i'm also learning as I go and an no means an expert

This question was timely for me!

g-love said:

I'm planning my system now and I was intending to go the route of Walker. That seems like the most logical in my head, but i'm also learning as I go and an no means an expert

This question was timely for me!

Click to expand...

Planning out the system is a lot of work, I get bogged down in trying to "see" the brew day sometimes. And This being my first HERMS, I always feel like I am missing something.

I know I ask a lot of questions here, but I always get awesome feed back.

I am going to work up some drawings pretty soon, to see if i can get a better idea of the brew day, and where things need to be plugged in, and so forth.

I think I can get the control box down to about $550 with 2 PIDs, if so I will go that route.

Tim

I personally still maintain that the output temperature from your Mash Tun is what you really care about. Who gives a rip what temperature the trickle of wort out of your heat exchanger is? You care about the overall mash. If it's possible for a PID to accurately control the temperature of the entire mash and prevent over-heating like was discussed earlier, then your MLT output temperature is what you really want.

Working off the HEX output and setting that to your desired mash temperature will get you to near your ideal mash tempearture, save for the small amount of heat loss from your MLT (which should be very slow) but it will take a long time to equalize.

Think about it - when we cool our wort after boiling - say we have 200* wort and we want to get to 70* - we don't pump 70* water through the chiller, we pump water as cold as possible through the chiller. Think about it as if we recirculated the wort back into the boil kettle - we have the exact same setup, just in reverse (cooling vs. heating) - you could pump 70* water through the chiller, and EVENTUALLY you'd drop the temperature down to 70*... but if you pump 40* water through the chiller you'll drop the temperature down MUCH quicker. And frankly you don't care if the wort coming out of the chiller is at 40* or 45* or 80* - you care if the temperature of the entire volume of wort is at 70* because THAT is your target.

Again - I recognize that there's some concern about overshoot, and I'll try and run a test on my next batch where I monitor off the MLT outlet vs the HLT water temp / what the HEX output would likely be. I think you might get faster ramp speeds, and if the PID can prevent overshoot you'll end up having a quicker overall brew day.

BadNewsBrewery said:

Working off the HEX output and setting that to your desired mash temperature will get you to near your ideal mash tempearture, save for the small amount of heat loss from your MLT (which should be very slow) but it will take a long time to equalize.

Click to expand...

It doesn't really take a long time to equalize.

If I dough in and my temp is too low, the heat turns on and boost the HLT water temp so that the wort exiting the coil is at mash temp. The temp on the coil output increases pretty fast when this is going on.

As soon as the coil output temp hits my set temp (which takes maybe a couple of minutes max) it stays constant and at my set temp as the wort from the MLT continues to pump through the coil.

At a couple gallons/min teansfer rate, all of the wort will have gone through the coil in a couple of minutes, and things are stable.

I understand where you are coming from and follow your thinking. I am just saying that the actual experience I have with my system (and others have with their similar systems) says otherwise.


EDIT: think about it this way: what I am doing is exactly what RIMS guys do from a high level. I pump worth through a heater and measure the temp coming out of the heater.

For maintaining temperature - absoloutely. If you dough in at the right temperature and the calculations all work out and your mash drops to within a degree or two of your desired temp and you don't want to change it, I'll agree that it shouldn't take more than a few minutes to equalize everything.

If you're doing a step mash with a few different temperatures, you'll probably get faster temperature changes by heating the HLT above your target temperature, and letting the heat transfer not only heat the wort, but cool the water in the HLT, and have both of them settle on the right temperature. Hopefully the PID will be able to do this.

We're debating a relatively small amount of time really, so this is more of a gentlemen's discussion vs. whether one should do it one way or another at this point - I think both methods would work fine, IF (and that's a big IF) the PID can learn the heating profile enough to take advantage of heating the HLT a little above your target temp and letting it cool back down while the wort and MLT heat up. If the PID can't effectively do that, then the debate is moot and measuring at the MLT / HEX outlet is the only way to go.

Did you just call me a gentleman, you son-of-a-*****!?

OK, so due to some issues at hand, a 1 PID system is back on the table.
IF someone could direct P-J to this thread I really wold like his help on this.

As it would look:

240@30amp supply
3 x 15 Gallon SS pot eHerms
HLT w/ 5500w 240v element and 50 SS HEX
1 PID with RTD
Boil Kettle with 5500w 240v element (I already have a BK Controller from High Gravity)
would be nice to have an outlet to plug the BK Control into in the box
switchcraft connectors for power from the box to the element.
i have one pump, and will ad a second so the ability to control 2 pumps would be nice as well

Also, i was planning on using the kit from Ebrewsupply, so a shopping list would be very helpful.
I could do more for my self if I was home, but beiing deployed to Afghanistan is making searching a lot hared.

agani thx for your help

Tim

Yes, so the 1 PID system is how I am going to go. With a $300 prebuild control for the Boil Kettle, I cant justify the extra $$ on the 2 PID Control.

So, the plan is -
1 PID/RTD monitering the mash temp at the exit of the HEX, controlling the element in the HLT.
2 pumps; 1 recirq the HLT water 1 Recirq the Mash.
2 110v outlets for the pumps
1 220 outlet for the element.

That sound about right? Did I miss anything?

Tim

Just a thought on the where to measure the temp, correct me if I'm wrong but I think both walker an badnews are controlling 2 different ways. I think walker is using the output temp to control the hlt temp, when the output temp is low the hlt gets hotter. badnews, on the other hand, is maintaining the hlt to a specific temperature. Which means the output of the coil should be fairly close to the temp of the hlt. That bein said the coil input is only being measured for info and should read closely to what the overall mlt temp should be. If that's the case, I think it's just 2 different ways to skin the cat

mrwizard0 said:

Just a thought on the where to measure the temp, correct me if I'm wrong but I think both walker an badnews are controlling 2 different ways. I think walker is using the output temp to control the hlt temp, when the output temp is low the hlt gets hotter. badnews, on the other hand, is maintaining the hlt to a specific temperature. Which means the output of the coil should be fairly close to the temp of the hlt. That bein said the coil input is only being measured for info and should read closely to what the overall mlt temp should be. If that's the case, I think it's just 2 different ways to skin the cat

Click to expand...

I believe you are correct, I ahve decided to measure the output of the HEX, to drive the MLT.

I will have an dial thermo on the HLT to keep an eye on the temp.
It would be easy enough to add a T and connection, and run the system both ways, and see what i like better. All my pots will have dial thermos...so compairnig temps would not be that hard.

Tim

I you buy a big enough enclosure, you can leave some space for a second pid later. Or if you want one of them to just read temps, there are a lot of controllers that are a lot cheaper than the auber ones that can just display temp. And you can definitely switch it up down the road to try it the other way. I currently maintain the hlt temp the same way as bad news and it works pretty well. I'm am still dialing it in though. Since I have 2 pids I can easily move the t my rtd is in to another spot

I have a cheap PID that does C only, The box will be just big enuff for 2 pids, but I wont hook it up for a while.

My RTD will have QDs so I can just move them around as I want

I use the output of my herms coil to control my HLT elements. I monitor the temp of the mash tun output. I agree with Walker that using the mash tun output temp to control the HLT elements would result in significant mash temp overshoot. I currently do 30 gallon batches and there is a big lag time between changes in herms coil output temps and changes in mash tun output temps. I used to do 15 gallon batches and it was much easier to change the mash temp with the herms.

Yes, I am sold on the new direction of the control box, later I will make it a 3 pid system, with one PID for the HLT, HEX output, and Mash Temp.
But for now...this will do well I think.

bad thing is, it is still 9 months away...buying all the parts so when I get home, I can put it all together.

T