How to control the boil with a heating element

gunner65 said:

Just a thought you have to replace one of the capacitors in that circuit to slow down the timer in order to control otherwise the pulseing is way to fast for boil kettles. Do a search as I cannot remeber the exact value of that.

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Are you talking about the Bakatronics PWM kit or Walker's design?

wilserbrewer said:

Interesting finding...."I could have just plugged it in and let it roll."

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In that post, Walker didn't specify his boil volume.

And 2 posts later he mentioned that 100% power results in a "Violent Boil" that shakes his entire stand.

Oooh... lookie here. Would this one work without an SSR? According to its rating, it would work for a 4000w or lower element at 220v.

bgrubb7 said:

Are you talking about the Bakatronics PWM kit or Walker's design?

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Bakatronics

NTabb said:

Guys,

I'm building an electric setup very close to Kai's, but I'm using the BCS-460 instead of a control panel. (by the way Kai, I'm going to owe you alot of beer for that info) My question is how do you control the boil with a 5500W element? If I wanted to brew a small 6 gallon batch I would have to imagine the boiloff would be too much without some type "dimming" solution.

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I have the BCS-460 controlling a 5500 watt element and it is super easy to control the boil. I can boil 5 or 10 gallon batches and control a hard or light rolling boil.

The simplest way I found was to set the target temperature for the boil kettle and set the control to 'PID' instead of 'duty cycle'. When I set the temp to 208, I get a nice rolling boil. The BCS allows you to set this value on the fly so it is easy to adjust the boil as needed.

NTabb said:

Any suggestions on what PID I could use?

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The BCS 460 is the PID, so having the BCS controlling a pair of SSRs is all you need to control the heating element.

Brent

bzomerlei said:

I have the BCS-460 controlling a 5500 watt element and it is super easy to control the boil. I can boil 5 or 10 gallon batches and control a hard or light rolling boil.

The simplest way I found was to set the target temperature for the boil kettle and set the control to 'PID' instead of 'duty cycle'. When I set the temp to 208, I get a nice rolling boil. The BCS allows you to set this value on the fly so it is easy to adjust the boil as needed.



The BCS 460 is the PID, so having the BCS controlling a pair of SSRs is all you need to control the heating element.

Brent

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Brent,

You may find that controlling the boil by temp is not real reliable. The problem is that there is no temp difference between rolling boil and violent, off the hook boil. When water reaches boiling temperature, it converts to vapor (steam), and doesn't get any hotter.

Duty cycle will allow you to adjust the boil by adjusting the amount of energy going into the kettle. With my BCS, I find that once I reach boiling, I set the duty cycle to about 65% with a 5500watt element to maintain a nice rolling, vigerous boil.

Ed

gunner65 said:

Just a thought you have to replace one of the capacitors in that circuit to slow down the timer in order to control otherwise the pulseing is way to fast for boil kettles. Do a search as I cannot remeber the exact value of that.

Click to expand...

If you are talking about my PWM circuit...No, you don't need to slow it down. You can pulse that sucker WAY faster than I'm doing it with that circuit and it will work.

In fact, I wish I would have made mine pulse faster than it does. Mine pulses ever 2.3 seconds. If I run it it half power, that's 1.15 seconds on and 1.15 seconds off, and you can literally see the boil pulsing in the kettle. VROOM-off-VROOM-off-...

wilserbrewer said:

Interesting finding...."I could have just plugged it in and let it roll."

Click to expand...

Ohio-Ed said:

In that post, Walker didn't specify his boil volume.

And 2 posts later he mentioned that 100% power results in a "Violent Boil" that shakes his entire stand.

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I pretty much always make 5 gallon batches. My boil volume at the start is about 7 gallons.

I have a single wrap of reflectix around my kettle (a converted sanke), and I can run the element (5500W) at 100% and nothing splashes out of the kettle at all. Yes, the boil is very strong, but it does not erupt.

And, yes, it does make my whole stand shake, but that's because my stand is a piece of crap. It's just an old lab table with thin square legs and no bracing down low on it, so it likes to shimmy back and forth. I need to put some braces at the bottom to stop this because I'm sure it's not good for the table's longevity.

bzomerlei said:

When I set the temp to 208, I get a nice rolling boil.

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I would argue that your temp probe is inaccurate. Wort shouldn't boil at 208*F.

And, like Ed mentioned, the temp of a boil is a constant. It doesn't matter if it's a nice gentle simmer or a table-shaking steam pumper.

Ohio-Ed said:

Brent,

Duty cycle will allow you to adjust the boil by adjusting the amount of energy going into the kettle. With my BCS, I find that once I reach boiling, I set the duty cycle to about 65% with a 5500watt element to maintain a nice rolling, vigerous boil.

Ed

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Ed,
So far I have done three batches, two 5.5 gallon and one 11 gallon, and the PID control based on the temp set point seems to work pretty well. It could be the placement of my temp probe, it is not right next to the elements so there is a small but measurable delta in the temp of the wort as I approach boiling temp. I'll keep an eye on it though.

Two questions:

• Do you find that you need to tweak the duty cycle percentage based on boil volume? My starting boil volume is usually 7 gallons and finishes around 5.6 gallons. It seems like less volume would take less energy.
• Do you set the duty cycle via state change in the BCS?

bzomerlei said:

Ed,
So far I have done three batches, two 5.5 gallon and one 11 gallon, and the PID control based on the temp set point seems to work pretty well. It could be the placement of my temp probe, it is not right next to the elements so there is a small but measurable delta in the temp of the wort as I approach boiling temp. I'll keep an eye on it though.

Two questions:

• Do you find that you need to tweak the duty cycle percentage based on boil volume? My starting boil volume is usually 7 gallons and finishes around 5.6 gallons. It seems like less volume would take less energy.
• Do you set the duty cycle via state change in the BCS?

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Yes, I have adjusted the %.

I have my BCS in PID mode until the BK reaches 209f (I think), then switch to Duty Cycle. From that point, I usually run the Boil in Manual Mode on the BCS, so it's very easy to adjust.

Ed.

Walker said:

I would argue that your temp probe is inaccurate. Wort shouldn't boil at 208*F.

And, like Ed mentioned, the temp of a boil is a constant. It doesn't matter if it's a nice gentle simmer or a table-shaking steam pumper.

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My probes were calibrated and the new Steinhart-Hart Coefficients put into the system. However, there are two factors that impact why I get a boil at this set point. First, as mentioned earlier in this thread, exact boil point is base on atmospheric pressure, since I am 500 ft above sea level, I'm boiling a a slightly lower temperature, like 211. The second factor is that this the the set point for the PID control. Once I am within 2 degrees +- of this set point the PID control cycles the power on/off in an attempt to hone in on the exact temperature. It is possible that the set point I selected is effectively resulting in a 65% duty cycle like Ohio-Ed uses above.

When I look at the data log, the recoded temp in the boil kettle is moving between 210-211 during the boil even though the PID set point is 208