Heating to much?


#1

Hi
Started a New brew a couple of days ago and noticed today that the brewpi heats every time the temp is a bit to low. Never seen it before. Normaly the temp from fermentation heats it up and the fridge cools it down. Its the old arduino brewpi and it has worked fine for several years. Anything I can do?


#2

Increase the minimum time for switching between heating and cooling, on the bottom of advanced settings.


#3

On the bottom of advanced settings I have “Trigger rotary encoder at every …” and I know its not that one :slight_smile:


#4

Anything called ‘dead time’ ? Have not used the Arduino version for quite a while.


#5

No. These are the settings under advanced settings/Control constants

Temperature idle range top

Temperature idle range bottom

Heating target upper bound

Heating target lower bound

Cooling target upper bound

Cooling target lower bound

Maximum time in seconds for heating overshoot estimator

Maximum time in seconds for cooling overshoot estimator

Beer fast filter delay time

Beer slow filter delay time

Beer slope filter delay time

Fridge fast filter delay time

Fridge slow filter delay time

Fridge slope filter delay time

Use light as heater


#6

Any idea?

Here’s a screenshot of an earlier brew. No heating at all.


#7

Ah ok. I looked at your chart again. Your fridge temperature continues to drop long after you stop cooling.

You are probably cooling the back of the fridge beyond what is needed and you have overshot before that cold reaches the sensor. Try moving the sensor closer to the back of the fridge.


#8

Thanks, I’ll have a look when I get home :slight_smile:


#9

Looking better :blush:
Moved the sensor to the back.
Thanks for your help :+1:


#10

Have a beer in the fermentor for about a week. How does my graph look? Seems a bit strange at the end of the graph?


#11

You’ll have to zoom in on that last part. Can’t give much feedback from this data, I need to see when it was cooling and heating.


#12

Sorry :slight_smile:


#13

I think you should try a higher kp and longer ti


#14

Pid kp? Where do I find ti?


#15

Right, arduino version. Lower Ki, increase Kp. The theory is that with kp too low, you’ll have the integrator increasing and decreasing to provide the action, which is slow. If the proportional part does more work, this is not needed.


#16

Thanks :blush:
By how much? Ki is 0,25 and kp is 5


#17

Try doubling Kp and halving Ki. Reduce Ki further if needed.