Recirculate BK?

[Bsquared]

So I'm brewing now with a 5500w element controlled by a bcs460. I have it set at PID 212.5 but It keeps fluctuating the reading between 209 to 214. So the boil is starting and stoping.

My question is every one recirculating to avoid this? Is my temp probe too close to the element, or can make an adjustment like setting the temp to 214?

 

[MaxOut]

When I boil I run the burner wide open so PID is not needed. Either set your temp to 250 or change output to directly control it on.

 

[iijakii]

Is it possible to do a manual percentage control with BCS like us PID users do?

 

[Bsquared]

Yes I can set a %. Ill have to look in to that, I think I can program it to run as a pid up to 209 or so then switch over to % control.

I ended up setting it to 214 and it held a nice rolling boil after I was down to 11.75 gallons, I think at 12.5 I might have had a boil over issue tough with it set to 214.

 

[DFP51]

I set mine to 205 and then switch it to manual. That seems about the highest I can go without boiling over. Once the temp hits 205, I switch to manual at 60 percent. The element visibly pulses at 60 percent, but it never stops boiling.

 

[TheZer]

To get rid of the pulsing, the BCS has another setting that will reduce the time between 'element on' and 'element off'.

I think default is set at 3 seconds. So for example, at 66%, the element is on for 2 seconds and off for 1 second. Change the default from 3 seconds to 1 second, then element is on for 0.66 seconds and off for 0.33 seconds, and pulsing is less noticeable.

You may be able to reduce the default to less than 1 second.

 

[MaxOut]

To get rid of the pulsing, the BCS has another setting that will reduce the time between 'element on' and 'element off'.

I think default is set at 3 seconds. So for example, at 66%, the element is on for 2 seconds and off for 1 second. Change the default from 3 seconds to 1 second, then element is on for 0.66 seconds and off for 0.33 seconds, and pulsing is less noticeable.

You may be able to reduce the default to less than 1 second.

Good idea but I would be concerned that you would wear the contactor out quickly with such rapid pulsing. Having a rheostat dial control would allow you to keep the element output full on at a reduced power once boil is achieved would be ideal. That way you could maintain boil and eliminate the constant on/off.

Example - Have BCS directly control element full on until 212 is reached then go to another state where the same element can be controlled through a rheostat manually set at min temp to maintain boil.

I prefer a wide open boil because it is easier to calculate total boil off when you are not turning heat on and off and I leave enough room in the BK to help avoid boil over’s. When my BCS reaches 209 a buzzer is sounded for 15 seconds, at this point I monitor the BK and manually override the burner as needed until the hot break settles and then let the BCS run the burner wide open until boil is over. Same process used on hop additions. I have my burners wired through a 3 position on/off/auto switches that allow me to override the BCS without interruption of the current running processes and timers.

 

[Bsquared]

I am using a 40A SSR to control the element so rapid cycling is not a problem. I'll have to try setting that up for my next brew to reduce the on/off delay to 1 second.

 

[crane]

Look at the datasheet for your SSR to determine its response time. It should be in the 10ms range. If so you can probably go below 1 second and be fine, but if it's above 100ms I would stay above 1 second. I ran into this problem on my meat smoker when I set the pwm frequency to 100Hz. It didn't heat at all because the SSR never actually turned the output on for the hot plate. I think I ended up setting it to 10Hz.

 

[ChuckO]

I also run a 5500w element from a BCS. I let it run at 100% until the boil starts and then switch to a process that has 5% steps from 45 to 80% PWM to control the boil. I can step up/down 5% at a time this way. I have the output period set to 1 second.

 

[TheZer]

Good idea but I would be concerned that you would wear the contactor out quickly with such rapid pulsing.

Just like others above, I'm controlling a 5500W element with a 40A SSR with 10ms response, so no worries.

 

[kerklein2]

Because of physics, just set your temp to 220 or something. Manual % duty cycle would be much more desirable though.

 

[Bsquared]

Because of physics, just set your temp to 220 or something. Manual % duty cycle would be much more desirable though.

I wish Sr. Isaac could help me here, but the problem here is that the energy required to maintain a good rolling boil, over no boil, or a Mt.St Hellen's erupting boil is a very fine line. I do have the option to set a manual %, but I will most likely go the route others have mentioned and shorten the cycling time.

 

[Bsquared]

Okay problem solved, set the BCS system settings for the BK out put to monitor temp every 0.5sec and have a differential of 1ºF and set the cycle output to 0.5 sec as well. I set the BK temp to 213.5 with these settings an had a really good boil with an evaporation rate of 1 gallon/hr.