Brewzilla Gen4 Discussion/Tips Talk

[SanPancho]

Regarding the calibration issue, they said they are not going to pursue that since I was the only person they've heard from. They don't beleive me and will only do so when others contact them with the same issue. I know 3 or 4 others with the same experince but for soem reason they are not contacting Kegland about it. Thus I have to live with a constant 2.5 degree difference. When I calibrate my probe thermometers, they are deadly accurate within the two ranges, so I can't see why the Brewzilla isn't. Kegland also doesn't seem to think that a 2.5 degree difference is all that significant. I totally disagree, especially after a most careful calibration. What's the pont of a calibration if it doesn't work? A lot of troulbe and time for nothing.

so when you did your calibration did it actually retain your new settings? or is the 2.5 +/- the error that remains AFTER you did the calibration?

i need to do mine but after seeing a few folks say that their calibration didn't "stick" in the machine, im wondering if its worth the trouble

 

[Bottoms_Up]

@Bottoms_Up
Your tool confirms my statement 500 foot elevation wouldn't make this reading change.

View attachment 807824

But you've since noted the typo I pointed out.

Interestingly you'd need to be at about 47000 feet for a boiling point of 111.3 F

Glad you are getting a little feedback from kegland now, kegland are a million times better to communicate with than KegKing.
I received no replies for weeks then the CEO called and said they were very busy and I should have contacted my local supplier not them at all. But local supplier can't get a response from them either.

Temperature errors and discrepancy across the brewing unit are a real nuisance.

Yes, your calculation confirms the value I got. It's only 1 degree difference, but why not put in the correct amount, sionce other errors accumulate.

Interesting, our local supplier tells us to contact Kegland not them!

 

[Bottoms_Up]

so when you did your calibration did it actually retain your new settings? or is the 2.5 +/- the error that remains AFTER you did the calibration?

i need to do mine but after seeing a few folks say that their calibration didn't "stick" in the machine, im wondering if its worth the trouble

Initially, the temperature was 7 degrees Fahrenheit out, but after the very careful (and time-consuming) 2-point calibration, it was 2.5 degrees out. Thus it is the error that remains after the calibration. The differences at each end were quite significant, and obviously incorrect. I think the boiling temperature was about 117 F! And the freezing temperature was quite below 32! So it did improve, but is still too far out, since I mostly make lagers and need extra special temperature control. Ales are not as demading when it comes to temperature cotnrol.

Tomeorrow I'm going to check the freezing point once again (this wil be the third time), since I'm wondering whether, if you're quite a bit out to start out with, doing the calibrations may just narrow the range in an iterative way. I have no idea how the calibration algorithm works (wish I did) so mayabe this is what I need to do. It's worth a check.

If that doesn't work, I'm going to do a 2-point calibration in the range in which I feel is most important (mashing temperatures). As long as that range is relatively accurate, I don't really care about the rest of the range. So, in case I do more than one mashing step, I might calibrate the range from about 120 F to 175 F. That will also include the mash out temperature.

I'll let you know if either these two approaches work.

 

[D-Max]

The boiling point at that altitude actually does change that much, that's why I mentioned it. Check this out:

Boiling Point at Altitude Calculator

Every time I've reported an issue with Kegland they dismiss me and say that "if that was true, why haven't they heard from others reporting the same problem?" The problem is that most likely most users have never bothered checking the accuracy of their equipment, or just don't bother to report it and work around it. I also work around it but feel its the responsible thing to do to always let the manufactuer know if there are issues so that they can correct it. I don't think Kegland really cares, as they now don't respond to me at all.

I've pointed out two programming errors and they refuse to admit it. I was a programmer for over 20 years and know that no programmer is perfect. I also do all my own brewing calculations (I don't use a Brewing Program) so know a little about programming. If one does a two-step calibration and enters both the freezing and boiling points accurately, the calibration program should be able to easily divide this by 100 (for Metric) or 180 (for Imperial) for the intermediate points. There is no way that an intermediate temperature should then be off by 3 degrees Fahrenheit as myself has found as well as one other person! At most one might expect a half degree or so. That other person's Brewziall was also 7 F out with the Factory calibrations as was mine and at least one other had the same issue.

Also, their RAPT app contains a programming error. If one sets the Brewzilla to Imperial, and checks the RAPT app, it will show the temperature in Metric - with an "F" for Imperial!! Sometimes it briefly shows the Imperial temperature but then quickly reverts to Metric. This should be a simple programming error to correct, yet the Kegland representative thanks me for bringing this to their attention by completely ignoring my email and refusing to respond.

It would be so easy to do the dilgent thing and check the program and see if there was indeed an error. There's absolutely no question that the RAPT app does contain an error. Anyone can easily check that but Kegland refuses to even so that. And logically, the calibration program HAS to contain an error. Dividing the two ranges and dividing by either 100 or 180 is a straight-forward mathematical exercise, so it should come out fairly accurate, not 3 degrees out! That simple check would elevate the credibility of the Brewzilla a lot. But they ignore single reports of issues, even if that person tells them that several others have had the same issue.

In fact, when I did the calibration for the boiling point, the Brewzilla read 219.2 F!!!! The freezing point was 26.8 F. There's no way those can be right!

@Bottoms_Up
Your tool confirms my statement 500 foot elevation wouldn't make this reading change.

View attachment 807824

But you've since noted the typo I pointed out.

Interestingly you'd need to be at about 47000 feet for a boiling point of 111.3 F

Glad you are getting a little feedback from kegland now, kegland are a million times better to communicate with than KegKing.
I received no replies for weeks then the CEO called and said they were very busy and I should have contacted my local supplier not them at all. But local supplier can't get a response from them either.

Temperature errors and discrepancy across the brewing unit are a real nuisance.

@Bottoms_Up
Your tool confirms my statement 500 foot elevation wouldn't make this reading change.

View attachment 807824

But you've since noted the typo I pointed out.

Interestingly you'd need to be at about 47000 feet for a boiling point of 111.3 F

Glad you are getting a little feedback from kegland now, kegland are a million times better to communicate with than KegKing.
I received no replies for weeks then the CEO called and said they were very busy and I should have contacted my local supplier not them at all. But local supplier can't get a response from them either.

Temperature errors and discrepancy across the brewing unit are a real nuisance.

My tupence - If you go to google earth and put the pointer on your brew area you will get the height above sea level. In my case here in NZ its 98 M which equates to a boiling temp of 99.7 degrees C

 

[mng8r]

I know 3 or 4 others with the same experience but for some reason they are not contacting Kegland about it. T

I purchased mine through MoreBeer and contacted MoreBeer directly about all of the issues I was seeing and experiencing. MoreBeer was great and exchanged the first one. They also accepted a return of the second one and refunded the purchase price, so I'm out of the game.

The last two straws were that the temp reading never got below 53C and the next morning, there was a puddle of water under the unit. It was difficult to tell where the leak was, but it wan't from one of the fittings. Perhaps it leaked around the sensor bung and that would explain why the temp readings went bad.

 

[Bottoms_Up]

I purchased mine through MoreBeer and contacted MoreBeer directly about all of the issues I was seeing and experiencing. MoreBeer was great and exchanged the first one. They also accepted a return of the second one and refunded the purchase price, so I'm out of the game.

The last two straws were that the temp reading never got below 53C and the next morning, there was a puddle of water under the unit. It was difficult to tell where the leak was, but it wan't from one of the fittings. Perhaps it leaked around the sensor bung and that would explain why the temp readings went bad.

That's a good point. Maybe most customers are reporting any issues directly to their supplier, and the supplier is not lettign Kegland know.

 

[Bottoms_Up]

Initially, the temperature was 7 degrees Fahrenheit out, but after the very careful (and time-consuming) 2-point calibration, it was 2.5 degrees out. Thus it is the error that remains after the calibration. The differences at each end were quite significant, and obviously incorrect. I think the boiling temperature was about 117 F! And the freezing temperature was quite below 32! So it did improve, but is still too far out, since I mostly make lagers and need extra special temperature control. Ales are not as demading when it comes to temperature cotnrol.

Tomeorrow I'm going to check the freezing point once again (this wil be the third time), since I'm wondering whether, if you're quite a bit out to start out with, doing the calibrations may just narrow the range in an iterative way. I have no idea how the calibration algorithm works (wish I did) so mayabe this is what I need to do. It's worth a check.

If that doesn't work, I'm going to do a 2-point calibration in the range in which I feel is most important (mashing temperatures). As long as that range is relatively accurate, I don't really care about the rest of the range. So, in case I do more than one mashing step, I might calibrate the range from about 120 F to 175 F. That will also include the mash out temperature.

I'll let you know if either these two approaches work.

So I put the theory to practice. I filled the Brewzilla with ice water, recirculated it, let it run for about 5-10 minutes until the temperature on the Brewzilla stabilized. Then I checked the temperature of the water with two accurate probe thermometers (accurate because both read the freezing and boiling temperatures accurately). I had calibrated the freezing point of the Brewzilla previously, but when I checked it this next time, it was 1.3 degrees out! It should have been accurate at that point which I had alrady set.

So, I assume that the algorithm of the calibration calculation somehow affects the first calibration point when the second one is set. So it is an iterative process. If the initial difference is a lot, then you may have to do the 2-point calibration 3 or 4 times to get it close. If it is only out a degree or two, one calibraiton should likely do it.

I will check it at room temperature later to see what the difference is this time. I haven't set the second calibration point again until I see what difference it has made so far. I assume I should be a little closer, but it will still be out a degree or a degree and a half. That is better than 7 degrees out the first time and 2.5 degrees out the last time.

 

[mng8r]

I had calibrated the freezing point of the Brewzilla previously, but when I checked it this next time, it was 1.3 degrees out!

Same thing that I found. It's accurate at the point you first calibrate, when you calibrate. Next time water temp reaches that point, the reading is not the same.

 

[Bottoms_Up]

Same thing that I found. It's accurate at the point you first calibrate, when you calibrate. Next time water temp reaches that point, the reading is not the same.

I think it indicates that the calibration has to be done several times in succession, not just once. Each time you correct one of the points, it changes the other. It does seem to get closer each time, though, so it has to be an iterative process.

Please let Kegland know. They keep telling me that nobody else has ever reported this problem to them, so they are unable (unwilling) to check it out.

 

[Bottoms_Up]

Same thing that I found. It's accurate at the point you first calibrate, when you calibrate. Next time water temp reaches that point, the reading is not the same.

Once you change one of the points, it affects the other point that you have already set. Thus you have to do the calibration several times in succession. Each time it gets closer.

Please let Kegland know as they tell me I am the ONLY person they have heard this from.

The person I spoke to is:

[email protected]

[Note - sorry for the repetition - when I checked earlier my message had disappeared so I re-wrote it. Now I see that it's back again]

 

[Bottoms_Up]

I think I now have a fix for the Brewzilla Gen 4 temperature calibration issue!

After my third attempt at trying to resolve the temperature difference on my Brewzilla, I think I sort of understand how the calibration algorithm works, at least in general. Knowing how it works is the first step of the solution. I was not able to find out from Kegland what the actual algorithm was, so I had to figure it out by logical deduction. I think the algorithm adjusts the entire temperature range rather than fix two points. Let me explain by using a simple example. I'll use the metric system as the example since there is exactly 100 degrees between the freezing point and the boiling point at sea level, so it is easier to illustrate. (For the Imperial system, it is obviously 180 degrees).

Let's say you measure your Brewzilla temperature with room temperature water, and find it reads low. This could be because the freezing point reads, let's say, 5 degrees too low and the boiling point reads 5 degrees too high. Thus there is a 110 degree range between the freezing point (0) and the boiling point (100). There should only be 100 degrees between these two points.

So you add ice water to the Brewzilla, run the recirculation arm and let the temperature adjust. The Brewzilla reads -5.0 C rather than 0. So you set the calibration point by raising it 5 degrees. Now there is a 105 degree spread between the freezing point and the boiling point rather than 110. Now when you read the water at room temperature, you are closer, but still it is out.

What has happened is that by raising it 5 degrees, you are still 5 degrees out in total. Brewzilla spreads this difference by splitting the 5 in half. So now when you go to the boiling point calibration, the Brewzilla reads 2.5 degrees too high. So you set the calibration point 2.5 degrees lower. Now you have a total range of 102.5. So the range still has 2.5 degrees too much. So it divides the difference, and now, if you were to go back to the freezing temperature, it would read 1.25 degrees too low. You adjust again. Each time the total difference will be halved as to what it was before. So you can repeat the calibration again and again until you feel it is close enough. It will never reach a range of exactly 100, because you are dividing the difference by a half each time.

So the bottom line is that if your Brewzilla is only a degree or two out initially, you may only need to do the calibration once. It should be close enough. But, if you are out by, for example, 7 degrees, as I was, you will need to repeat the calibration at least 3 times, or whenever you can live with the difference.

Note that my explanation is a simplification based on observation and deduction. There may be additional factors in the calibration algorithm, but I think that it is basically how it works.

I think there might be a trick to do it just once. If you were to initially take the reading at the freezing point as well as at the boiling point, and determine the entire spread (e.g. let's say 110 degrees), then if you were to just add that entire difference (10 degrees) at the freezing point calibration (rather than the correct temperature at that point), you should end up with the right range immediately, and thus all the temperatures should line up. Or even easier, rather than going back to the freezing point again, just make the adjustments while you're at the boiling point - and lower it by the difference. That way you only have to do it once.

I haven't tried this, but if anyone does, please let us know how it turned out.

 

[D-Max]

I think it indicates that the calibration has to be done several times in succession, not just once. Each time you correct one of the points, it changes the other. It does seem to get closer each time, though, so it has to be an iterative process.

Please let Kegland know. They keep telling me that nobody else has ever reported this problem to them, so they are unable (unwilling) to check it out.

Guys. You are playing with a non linear temp probe. Yes you could write software to correct the measurement but it would be infinitely easier to use a linear resistance probe that once calibrated would stay calibrated. Step back and ask the question of "What are Kegland's plans heading forward in 2023. They have a great brewing vessel but a hopeless temperature measurement and hence control system. I'm working on my own solution which will be external to the BZ.
I repeat - First accurate repeatable temperature measurement.
Second an actual PID control unit that will control the mash temperature to my requirements. Cheers.

 

[Bottoms_Up]

Guys. You are playing with a non linear temp probe. Yes you could write software to correct the measurement but it would be infinitely easier to use a linear resistance probe that once calibrated would stay calibrated. Step back and ask the question of "What are Kegland's plans heading forward in 2023. They have a great brewing vessel but a hopeless temperature measurement and hence control system. I'm working on my own solution which will be external to the BZ.
I repeat - First accurate repeatable temperature measurement.
Second an actual PID control unit that will control the mash temperature to my requirements. Cheers.

I think the Brewzilla itself is an excellent piece of equipment for the price. Where Kegland failed is in two areas. 1) the RAPT controller; and 2) sufficient documentation. The RAPT controller does not seem to be part of Kegland but something outreached. The factory calibration is not done by using two different temperatures, but using an electrical resistance on a theoretical basis. Maybe this worked for past Brewzillas, but it is obviously not working in the Brewzillas sent out since the Fall. Are they dumping the inefective machines on the western world? They are not willing to admit this new issue and still base all their comments on previous products. I know this wasn't an issue with the 3.1.1 Brewzilla as I have several friends who have one.

The documentation is inferior. I mentioned to them about 4 months ago that there is almost no information about all the default settings and what it means. They said they would correct this and include it in the next update of the manual. I have not seen this to date. ALSO, the PID default settings are not proper for most set-ups. Luckily there are now several videos that explain what more preferred settings should be set at.

The documentation about the 2-point calibration is incomplete and misleading, likely because Kegland has no or little understanding of the algorithm that it uses to calibrate. It doesn't mention that the calibrations must be done repeatedly to narrow the range until it is within an acceptable range. Instead it seems to imply that a single calibration is all that is necessary. I have mentioned this above.

All these things are very simple to correct. Yet they seem to refuse to do so for whatever reason. They seriously need to understand the RAPT technology and address certain issues with their manufacturer. Without fairly accurate temperature control, a brewing system is useless, especially for those brewing the more demanding lagers or other specialty beers. Ales are generally far more forgiving w.r.t. temperatures. Temperature should be the key to the system if they are to satisfy different brewing preferences. Even a cheap $20 kitchen temperature probe is far more accurate than this RAPT probe! Check it out at freezing and boiling temperatures! I bet it won't be out more than a degree or so. Yet the Brewzilla can be out by 6 or 7 degrees!

D-Max, you mentioned that your do-yourself assembled probe was built for less than $20, and it provides accuracy as well as accurate and effective PID functionality. Why can't Kegland do the same? They should throw out the useless stainless steel chiller - which must cost more than $20 - and exchange that cost to add to the accuracy of the temperature probe.

The whole point of brewing is specific, and accurate, temperature control. Yet that seems to be at the bottom of Kegland's priorities!

 

[SanPancho]

I think I now have a fix for the Brewzilla Gen 4 temperature calibration issue!



I think there might be a trick to do it just once. If you were to initially take the reading at the freezing point as well as at the boiling point, and determine the entire spread (e.g. let's say 110 degrees), then if you were to just add that entire difference (10 degrees) at the freezing point calibration (rather than the correct temperature at that point), you should end up with the right range immediately, and thus all the temperatures should line up. Or even easier, rather than going back to the freezing point again, just make the adjustments while you're at the boiling point - and lower it by the difference. That way you only have to do it once.

i'm game. i'll go ahead and do the calibrations in C to make it easy.

that way i'll have some data to submit when i email them about the temp problems.

on different note- how do we DIY that crappy "alert" function to actually be something you'd notice? any idea of how to turn an email into more of an actual "loud-noise-from-phone" type alert? was wondering if you could somehow turn the email into a text or something like that, maybe via google voice? set that "caller" to have a really loud/annoying notification sound. etc. really dont care about the contents of email i dont think, just want some way to make my phone do a noisy alert...

 

[govner1]

I'd look out for a 65litre brewzilla 3 and fit it with a SMARTPID, whirlpool and add in some other sensors, my modded Guten 70 works great.

Thanks but I think the Brewtools systems are much better optiooand their performance and the ability to replace individual components is a very nice plus.

 

[SanPancho]

ok, so i goofed up. thought i had alot more ice than i actually had on hand. oh well. so i modified and just tried to calibrate the mash temp range. also forgot to switch into celsius.

so -
ADC reading was 1890 at what my thermometer showed to be 138F
ADC reading of 1258 at what i showed as 170F.

that was with the pump running less than half open to get circulation and uniformity (hopefully). so those are saved. i'll re-heat tomorrow morning and see what sort of discrepancy i get at the unit's readings of 138 and 170.

 

[D-Max]

Guys. You are playing with a non linear temp probe. Yes you could write software to correct the measurement but it would be infinitely easier to use a linear resistance probe that once calibrated would stay calibrated. Step back and ask the question of "What are Kegland's plans heading forward in 2023. They have a great brewing vessel but a hopeless temperature measurement and hence control system. I'm working on my own solution which will be external to the BZ.
I repeat - First accurate repeatable temperature measurement.
Second an actual PID control unit that will control the mash temperature to my requirements. Cheers.

http://www.manoraz.com/_Uploads/dbsAttachedFiles/PT-100_Table.pdf

 

[Bottoms_Up]

ok, so i goofed up. thought i had alot more ice than i actually had on hand. oh well. so i modified and just tried to calibrate the mash temp range. also forgot to switch into celsius.

so -
ADC reading was 1890 at what my thermometer showed to be 138F
ADC reading of 1258 at what i showed as 170F.

that was with the pump running less than half open to get circulation and uniformity (hopefully). so those are saved. i'll re-heat tomorrow morning and see what sort of discrepancy i get at the unit's readings of 138 and 170.

Do you have any idea on how to interpret the ADC numbers? I know they represent the analogue to digital conversion, but what exactly do they mean?

Regarding the 2-point calibration at 138 F and 170 F, you may still have to do the calibration 2 or 3 times to narrow the range each time you clip some off from either end. Either that, or take the Brewzilla temperature at each point (as measured with your temperature probe) and take the entire difference in range off from one end. Then check. At least in theory that should bring you much closer and faster.

 

[SanPancho]

Do you have any idea on how to interpret the ADC numbers? I know they represent the analogue to digital conversion, but what exactly do they mean?

Regarding the 2-point calibration at 138 F and 170 F, you may still have to do the calibration 2 or 3 times to narrow the range each time you clip some off from either end. Either that, or take the Brewzilla temperature at each point (as measured with your temperature probe) and take the entire difference in range off from one end. Then check. At least in theory that should bring you much closer and faster.

well maybe im not understanding how you're doing things on each pass. from what i see you have to erase all your settings and re-enter them so im not sure i wanna do that until we establish just what exactly the math is. unfortunately i wasnt able to do 32F so my scale will be off vs someone who did the freezing/boiling set points. maybe i'll leave some water outside tonite and that'll get me close.

im guessing the adc numbers have some equivalency to a reverse temp scale. at sea level you boil at 212, so there's no way it can go higher unless you're under pressure, i.e. distilling, which 90% of folks arent doing i'd guess. so they likely set adc to zero or 1000 or whatever they wanna name it, at boiling/212f/100c. then adc runs higher the lower the temp goes, i.e. larger the difference from boiling. (difference in electrical resistance?) you can probably plot it out and figure the data from there.

in any case, here's what i had this morning after setting my calibration last nite using 138f and 170f-
display 140 and i show 138.2
display 155 and i have 152.6
display 170 and i show 169.7

so the range tightens up considerably, however its got its widest discrepancy right where i want it to be the most accurate- in the low to middle of that mash range. if the highest calibrated temp is the fixed reference point then it would make sense i guess, since the adc numbers seem to indicate boiling/212f/100c is the "start" point. and if so, maybe i should make my highest calibration point the one i am most concerned about and least likely to ever go over in a mash, so maybe like 155? hopefully that would mean that my 150s are pretty accurate, and upper 140s too.

 

[Bottoms_Up]

well maybe im not understanding how you're doing things on each pass. from what i see you have to erase all your settings and re-enter them so im not sure i wanna do that until we establish just what exactly the math is. unfortunately i wasnt able to do 32F so my scale will be off vs someone who did the freezing/boiling set points. maybe i'll leave some water outside tonite and that'll get me close.

im guessing the adc numbers have some equivalency to a reverse temp scale. at sea level you boil at 212, so there's no way it can go higher unless you're under pressure, i.e. distilling, which 90% of folks arent doing i'd guess. so they likely set adc to zero or 1000 or whatever they wanna name it, at boiling/212f/100c. then adc runs higher the lower the temp goes, i.e. larger the difference from boiling. (difference in electrical resistance?) you can probably plot it out and figure the data from there.

in any case, here's what i had this morning after setting my calibration last nite using 138f and 170f-
display 140 and i show 138.2
display 155 and i have 152.6
display 170 and i show 169.7

so the range tightens up considerably, however its got its widest discrepancy right where i want it to be the most accurate- in the low to middle of that mash range. if the highest calibrated temp is the fixed reference point then it would make sense i guess, since the adc numbers seem to indicate boiling/212f/100c is the "start" point. and if so, maybe i should make my highest calibration point the one i am most concerned about and least likely to ever go over in a mash, so maybe like 155? hopefully that would mean that my 150s are pretty accurate, and upper 140s too.

I'm not sure why you would want to erase the settings each time you do a calibration, since you want to retain the earlier calibration results. The next calibration then makes the end results closer. I have been leaving a pail of water outside overnight, which brings it close to freezing temperature. Then I just add a few blocks of ice (what you have in a couple of trays in the freezer might be enough) to get it down to freezing.

It sure would be nice to know where the fixed reference temperature point actually is. I assumed it was closer to the middle since I had similar differences at both the freezing point and the boiling point (it was initially 6.3 F degrees low at the freezing point and 7.2 F degrees high at the boiling point.

Your data of decreasing differences as the temperature increases is interesting. I do know that as you circulate, the temperature differences continue to narrow over a period of at least 10 minutes, so the differences you are seeing 'may be a reflection of time and not an indication that the fixed point is at the boiling point. So many questions!

I sure wish I knew what actual algorithm is used, and what the fixed point is. It would add much more understanding of the factors influencing the calibration.

 

[agentbud]

I wonder if it would be worthwhile or do any good to ask Kegland if they would care to join in this forum conversation. If it was my company, I sure would.

 

[Bottoms_Up]

I wonder if it would be worthwhile or do any good to ask Kegland if they would care to join in this forum conversation. If it was my company, I sure would.

I've mentioned to them that there are several people having similar experiences on a forum I'm on, and offered to let them know the link. They were not interested. They seem to rather not know if there are issues, and will only consider them if more than one person notifies them about the same issue.

 

[Bottoms_Up]

Based on the following, the "fixed" reference point does seem to be towards the middle, where the linear "correct" line ("ideal response") intersects with the linear "incorrect" line( "actual response"):

Calibrating Sensors

However, this can't be correct, since it would indicate that the mid-point temperature (i.e. about 122 F) remains correct, which does not seem to be the case, although I never specifically checked it at that temperature. Even if it wasn't the mid-point, if the two lines intersect, then it has to be correct somewhere in the range.

 

[Bottoms_Up]

Based on the following, the "fixed" reference point does seem to be towards the middle, where the linear "correct" line ("ideal response") intersects with the linear "incorrect" line( "actual response"):

Calibrating Sensors

However, this can't be correct, since it would indicate that the mid-point temperature (i.e. about 122 F) remains correct, which does not seem to be the case, although I never specifically checked it at that temperature. Even if it wasn't the mid-point, if the two lines intersect, then it has to be correct somewhere in the range.

It could be that the two slopes don't intersect at all:

Source:
The two-point calibration procedure - ppt download

 

[SanPancho]

I'm not sure why you would want to erase the settings each time you do a calibration, since you want to retain the earlier calibration results. The next calibration then makes the end results closer. I have been leaving a pail of water outside overnight, which brings it close to freezing temperature. Then I just add a few blocks of ice (what you have in a couple of trays in the freezer might be enough) to get it down to freezing.

It sure would be nice to know where the fixed reference temperature point actually is. I assumed it was closer to the middle since I had similar differences at both the freezing point and the boiling point (it was initially 6.3 F degrees low at the freezing point and 7.2 F degrees high at the boiling point.

Your data of decreasing differences as the temperature increases is interesting. I do know that as you circulate, the temperature differences continue to narrow over a period of at least 10 minutes, so the differences you are seeing 'may be a reflection of time and not an indication that the fixed point is at the boiling point. So many questions!

I sure wish I knew what actual algorithm is used, and what the fixed point is. It would add much more understanding of the factors influencing the calibration.

The fixed point has to be boiling at sea level. It’s the only logical answer because unless you’re using pressure there’s no way to go over that temperature by boiling. It’s as close to a constant as you can get. And the adc numbers increase as you move away from it which seems to correlate with it being the reference point.

As for doing second round of calibration you might need to screenshot yours as I didn’t see anything that looked like I could add another reference temp when I got into that menu. Just the saved data from my calibration.

 

[Bottoms_Up]

The fixed point has to be boiling at sea level. It’s the only logical answer because unless you’re using pressure there’s no way to go over that temperature by boiling. It’s as close to a constant as you can get. And the adc numbers increase as you move away from it which seems to correlate with it being the reference point.

As for doing second round of calibration you might need to screenshot yours as I didn’t see anything that looked like I could add another reference temp when I got into that menu. Just the saved data from my calibration.

Regarding the second round of calibration, you simply add freezing ice water, then check it with an accurate probe thermometer. Then add that value into Calibration Point 1 once again as you did the first time. This changes the slope of the line each time you do it, and so it gets closer. The calibration points are retained each time, so you don't want to erase them at all, as they're used for the next calibration. It is an iterative process where the slope becomes closer to the ideal each time you do another calibration.

 

[agentbud]

Just spit balling here.... when you do your calibration, where in the cooled/heated liquid are you placing the external temp probe to get the "accurate" reading? If it is being placed in the middle of the malt pipe, I wonder if the temps would be closer if you tested down at the bottom of the boiler right next to the built-in probe. In other words, is the problem with the temp difference actually a problem with the probe or rather a problem (as has already been discussed elsewhere) with the way the liquid circulates and is drawn straight to the drain hole instead of out next to the probe. I know kegland has recognized this to be an issue and is releasing a heat exchanger plate (HED) that will force the circulating liquid to go out to the edge and down past the sensor, in theory to provide a more even temp throughout. I don't think the HED has been released in the US yet but it would be interesting to hear from someone who gets one if that helps with the temp differences without having to do a calibration.

 

[Bottoms_Up]

Just spit balling here.... when you do your calibration, where in the cooled/heated liquid are you placing the external temp probe to get the "accurate" reading? If it is being placed in the middle of the malt pipe, I wonder if the temps would be closer if you tested down at the bottom of the boiler right next to the built-in probe. In other words, is the problem with the temp difference actually a problem with the probe or rather a problem (as has already been discussed elsewhere) with the way the liquid circulates and is drawn straight to the drain hole instead of out next to the probe. I know kegland has recognized this to be an issue and is releasing a heat exchanger plate (HED) that will force the circulating liquid to go out to the edge and down past the sensor, in theory to provide a more even temp throughout. I don't think the HED has been released in the US yet but it would be interesting to hear from someone who gets one if that helps with the temp differences without having to do a calibration.

Unfortunately, the boiler area is not accessible for direct measuring, so one has to check the liquid in the malt pipe. But before doing that, I have the recirculation pump on full blast and let it recirculate for at least 5 minutes until the temperature stabilizes. It might be a few tenths of a degree different than the area around the probe, but I don't think it should be significant after it has recirculated for some time. It does change during those 5 minutes. Also, recirculation is much better without the malt pipe and screen also inserted, so I do the calibrations with just water and no malt pipe, and about 10 liters of water for more consistency.

I am waiting for the heat exchange plate to become available here. That will certainly help when the malt pipe is inserted along with the grain. But I don't think the difference will be as noticeable when only water is used without the malt pipe.

 

[Bottoms_Up]

So correct me if my understanding is wrong. The ADC numbers are digitial numbers that convert the resistance readings from the temperature probe, which change with temperature. From the freezing point to the boiling point, the resistance changes in a relatively flat line (only slightly curved) but outside that range it curves more dramatically. So the algorithm matches each ADC number with an assumed temperature.

The factory calibration assumes a certain ADC number matches the freezing point and another matches the boiling point. The intervening ADC numbers are assigned a temperature reading based on that line (or slight curve).

In reality, those resistances may not be quite right for whatever reason, so a 2-point calibration has to be done.

At the freezing point, the ADC number that happens to be reading at that temperature gets assigned to 32 (when considering the Imperial measurement).

When one now goes to the boiling point and assigns the ADC number registered at that temperature to 212 (assumed at sea level), we now have two points of the range defined. All the intervening points are assigned temperature values according to the interpolation of the straight line or slight curve between those two points.

Thus, theoretically, if this understanding is correct, there should be no need for a second calibration at all.

But this is not the case. In practice, the result of the first calibration can still result in incorrect temperature readings. In practice, a second calibration does improve that significantly.

From my own experience, the ADC number at the boiling point is about 3920, and the ADC number at freezing point is about 630.

So where is my understanding not correct?

 

[D-Max]

Based on the following, the "fixed" reference point does seem to be towards the middle, where the linear "correct" line ("ideal response") intersects with the linear "incorrect" line( "actual response"):

View attachment 807929

Calibrating Sensors

However, this can't be correct, since it would indicate that the mid-point temperature (i.e. about 122 F) remains correct, which does not seem to be the case, although I never specifically checked it at that temperature. Even if it wasn't the mid-point, if the two lines intersect, then it has to be correct somewhere in the range.

I repeat - A linear output from the temperature measuring probe removes all the issues you are talking about. Yes you can program corrections for a non linear probe but that's messing with their setup. Any input into their program would not correct the temperature control function that we are all experiencing problems with. The solution is to collectively take their hand and gently guide them to the requirements of actual brewers, their customers. Results for them, increased sales and increased profits but most important, happy brewing customers. Cheers