My thoughts are still too much grain particulate in the wort. You need to clarify the wort more before boiling.
Just an update on this, after reading the suggestions from the posts i just redid the high gravity batch and set the max output on the PID to 80% and replaced the element with a brand new Camco ULWD element (http://www.amazon.com/dp/B000BPG4LI/?tag=skimlinks_replacement-20)
I again had minor scorching, only a few parts of the element had black scorch build up on it but there is a slight but noticeable burnt taste to the batch... it must be the particulate in the batch from not sparging..
To sum up.
Three scorched high gravity batches
Element was checked post mash so it is definitely happening during the boil
Fine mesh BIAB from http://www.biab-brewing.com/
Element set to max 80%
Brand new element
I appreciate all the input to date.. any suggestions now?
What's the cycle time on your PID set to? If it's set to e.g. 10s, and you set it to 80% power, then you'll get full power for 8s, followed by no power for 2s. 8s at full power might be enough to heat the element enough to start the wort scorching. You should be able to see the cycle time by watching the Output LED flash in Manual mode.
Reducing the power via phase angle control (SSVR) or a fast PWM (Auber DSP, if I've understood how that works correctly) gives you true low power operation, rather than a slow on/off pulsing.
what were the ingredients of the wort? gravity? and whats your process? do you recirculate during the mash (This increases efficiency and makes the wort clear if done correctly) and yes many people do this with BIAB as well since I would think the liquid around the element is otherwise more confirned and stratification and scorching is more likely.
I cant remember but are you placing the bag directly onto the element or do you have a false bottom to keep it away from the element surface... If I remember you did state that the wort is scorching AFTER the bag is removed but I just dont see how...then again we dont know what the gravity of the liquid is in question.
Personally I dont know why you would go with a 5500w element instead of a 4500w element they are the same size and unless you are brewing 15 gallon+ size BIAB batches it is overkill and the higher watt density is more likely to cause problems like this than the 4500w.
I use 4500w elements and bring my HLT with 15 gallons in it from 55 to 163 in about 30 minutes... and I get a very vigorous boil on 11.5 gallons with my pid set at 75% (1 gallon per hour boiloff)
My thoughts are still too much grain particulate in the wort. You need to clarify the wort more before boiling.
What's the cycle time on your PID set to? If it's set to e.g. 10s, and you set it to 80% power, then you'll get full power for 8s, followed by no power for 2s. 8s at full power might be enough to heat the element enough to start the wort scorching. You should be able to see the cycle time by watching the Output LED flash in Manual mode.
Reducing the power via phase angle control (SSVR) or a fast PWM (Auber DSP, if I've understood how that works correctly) gives you true low power operation, rather than a slow on/off pulsing.
+1 regarding the Auber DSP controller for boil kettles. I just switched my system from a pulse-width modulator to the DSP last month and I have to say that I think the DSP is better...plus it has a nice little readout of what the % power is set at. Great unit.
That device is PWM. The frequency is 100/60 Hz and the duty cycle is based on the dial, 0-100%, with a resolution of 1%.
I like the device, I'll probably use it myself when I rebuild.
I used both a PID and this device for my control panel. I haven't really used manual mode in the PID so I can't compare but I really like the knob on this device. I'm doing single vessel recirculating eBIAB btw.
On my 4352 I set the cycle time to 1 sec which is no problem for an ssr and raise SV till I get a good boil which for me is 213. Why not let the PID do the calculations?
OK think this out for a second before you take some customer service reps or marketing reps word as gospel....Wort was only 2 row and 7% amber malt, the bag is too fine and i can't recirculate the wort during the mash anymore. The original intent was to recirculate but the bag won't allow it.
Wort is 100% no question scorching during the boil, as i said this is easily verified by draining the kettle and checking the element prior to the boil which i have done both times.
Preboil gravity both times was 1.065, both were 90 min boils.
In regards to the 4500 vs the 5500 there is no difference watts / square inch... this keeps coming up but it isn't an issue. Directly from the Camco catalogue
"Ultra low watt density: burns at 50 watts per square inch - Resists dry firing -
Best when water has high mineral content - Heats in lime and sand buildup that would burn out ordinary elements"
ULWD is a classification of elements that all have 50W/sqin
LWD is a classification of elements that all have 75W/sqin
Standard is a classification of elements that all have 150W/sqin
Because the PID isn't doing and can't do the calculations when the liquid it's controlling is going through a phase transition. As the liquid it's controlling the temperature of passes through boiling point, there's no change in temperature as you add more heat. The feedback loop the PID is operating fails at boiling point.
By setting the SV to 213, assuming your boiling point is in the typical 211 to 212.5 range seen at sea level (it varies with the air pressure and wort composition), you've really just set your element to be on full power, except when the convection of the wort causes temperature fluctuations at the sensor. This doesn't achieve the aim of reducing the power supplied to the wort to maintain a steady boil. Now, you may be lucky in that the fluctuations at the sensor caused by convection do a reasonable job of controlling your boil, but that's going to be very variable, based on the wort type and anything that causes variations in bubble formation during boiling. Change something in your kettle, and you will likely get a very different average power supplied to the wort and different boil-off rate.
Yup, you're right. Because my controller is a ramp/soak I didn't get that nice PWM the other controllers have so the 1 sec cycle achieves the same results and yes the boil sits at 211.5 which is 1.5 off SV so the PID is cycling the element maintaining a steady boil.
OK think this out for a second before you take some customer service reps or marketing reps word as gospel....
A camco doesn't make the elements with there name on it they are a distributor that has other manufactuers make the stuff they label as thier own in many cases as well as this one. (my ace hardware branded elements are made by the same oem manufacturer and are identical in every way.)
B , both the camco ripple 4500w and 5500w elements share the same dimensions... they are both 14.6 overall length and the elements are the same diameter.... so therefore they both have the same surface area, Now the straight "non ripple" elements camco also markets as ulwd are much shorter than the ripple elements and have less sq inches of element surface than the ripple units.....
Now please explain to me how since the ripple units have the same sq inch of surface area but different wattages applieto that surface area how the watt density can be the same between the 2 ripple units let alone the straight vs longer ripple units as you say they told you.
Also I would like to know how camco can say the same about the smaller 11.22 length 4500 and 5500w elements they market as ulwd when there are lwd elements with more surface area and the same wattage? Can the lime life surface really lower the wattage applied or are they just marketed that way because they are less likely to acquire mineral build up from hard water ?
What is the part number of the Auber manual control and do you wire it up to the same SSR as the PID to the same inputs? That is a nice looking setup.
One thing we all need to remember is that these water heater elements (either LWD or ULWD) are intended to heat water in a tank pressurized to 60 or so psi. At a typical hot water tank pressure the boiling point of water is just under 300F. The point being that they are not designed to boil but rather heat water.
......
Since PID control will not work in the phase change realm of boiling, we have no choice but to reduce to a low CONSTANT power level that limits the surface temperature of the element during boiling.
My two cents for this very interesting conversation.![]()
I'm dying to know the MODEL NUMBER of the element. Several times the OP mentioned he polished it up until it was "shiny". My Camco 5500w ripple element, 02962/02963, is dull gray. It was never shiny. My understanding is that the shiny coating is only found on LWD or normal WD elements. It's also something to avoid as it comes off in the wort environment (based on reviews I've read).
I can't say whether the watt density is the difference, but I've never seen a shiny 5500w ripple element before. I'm just trying to eliminate variables here.
From what I understand and the way mine work it wouldnt cycle through anything if this was the case? it would just stay on at 100% duty cycle while attempting to reach the unobtainable setpoint in the most efficient way.... and with say 5 gallons and a 5500w element that would lead to an extremely violent boil and hotter a hotter element surface right? I generally boil at 65-70% with a smaller 4500w element and 6.5 gallons...
http://www.auberins.com/index.php?main_page=product_info&cPath=2_30&products_id=444
DSPR1
I do have them both controlling one SSR. That's what the 3 selector switch is for. I have it wired to use either the PID or PWM. I used 3 sets of NO contact switches to wire it. 1 set for power, the other 2 sets for the + and - terminals of the SSR.
My setup is a modified scaled back Kal clone from theelectricbrewery.com
I used both a PID and this device for my control panel. I haven't really used manual mode in the PID so I can't compare but I really like the knob on this device. I'm doing single vessel recirculating eBIAB btw.
mine increases to 100% output within a matter of minutes....I tried it yesterday but Im using a different pid with different setting set for pid operation. I would think setting your up the way you have it would make it work less efficiently for other processes and if you only use it for the boil it makes more sense to me to just spend the $20 for a pid with manual mode and avoid all this but if it works for you thats cool its your system after all...The PID calculates a precise power output based on an algorithm that considers the system, time off setpoint and number of degrees off setpoint. These parameters are set in auto tune when you set up your controller. Two other parameters to be concerned with are HY and T. Hy is hysteresis and tells the controller how much the PV can deviate, I set mine to 0. T is cycle time which for an ssr is 2. What does this mean? Let's say the PV is .1 below SV and the PID has calculated 10% power, the element will come on for .2 seconds and be off for 1.8 secs (t=2sec). :hs: 10% duty cycle :hs:
As I said earlier I set mine to 213 for a nice boil based on my parameter settings and a 90 minute boil. A longer boil could be a problem as I (PID) would start increasing the ramp over time
mine increases to 100% output within a matter of minutes....i tried it yesterday but im using a different pid with different setting set for pid operation. I would think setting your up the way you have it would make it work less efficiently for other processes and if you only use it for the boil it makes more sense to me to just spend the $20 for a pid with manual mode and avoid all this but if it works for you thats cool its your system after all...
$20...
I mill finely, BIAB, and squeeze the bag. I get a ton of break material in the kettle post-mash / pre-boil.