Water flow control


#1

Hi All,

Is it possible for the BrewPi to maintain temperature via flow rates? If so what pump would/are people using and how did they go about doing it?

Cheers


#2

Most pumps can only be turned On/Off, but if you let BrewPi control the On/Off percentage with PWM, it works well. I am using this to control the temperature of my conical.
For example: 10 sec on, 50 sec OFF, repeating every minute. The ON percentage is determined by the PID.


#3

Does anyone have details on possible setups for this? I was thinking about something like https://community.brewpi.com/uploads/default/original/2X/b/b4a5248bf17f18529180bd5a69ccfb3f6a6cc396.png, with a water reservoir in a fridge, and a pump that sends cool water through an immersion chiller permanently built into my fermenter.


#4

That’s my setup.

I have set the beer-to-fridge PID to 0, 0, 0. That causes the fridge setpoint to be equal to the beer setpoint. (because the actuators are coupled to fridge temp). Then you can run with only a beer sensor (because the fridge sensor will fall back on the beer sensor is no fridge sensor is found).

With the PID for the heater and cooler, you can then adjust your control algorithm.
I use a 10 min cycle for the pump, with a minimum on and off time of 10 seconds.

However, based on my setup (with a very powerful upright glass door freezer), I do not recommend the reservoir in fridge approach. It is fine for keeping the beer around 20C, but for cold crashing the heat exchange between fridge air and glycol reservoir is not efficient enough.

Think of it like this: you have a very big radioator to the hot air outside the fridge and a smaller radiator to the cold air inside the fridge. Your equilibrium will be somewhere in between outside and fridge temp, you cannot reach the fridge temp with the beer. I would recommend a glycol or beer line chiller that can cool the liquid directly, instead of putting the liquid in a fridge. I have now added extra insulation to my conical and with the fridge around 1C, I still cannot get the beer lower than 8C.
With a cooler that can cool liquid directly, you will have no problem cold crashing to 1C.

Here’s a photo of my setup:


#5

Hi Elco,
Do you have any news on when the 24 V brewing pump will be back on stock
Cheers Ken


#6

Maybe resurrecting a 5 month old thread is not the best way to ask this question, but the pumps are in production and are expected to ship to me on October 16. So they’ll be in stock again around October 25 if there are no delays.


#7

I built something similar; as we have 10 fermenters to cool, I sealed up a 50gal freezer, and installed 50’ of 1/2" copper tube that we run a small glycol bath through. THEN, we put a 1/2" PVC pipe as a supply rail for the 34f water supply. Each fermenter has a valve that opens when the PID reaches temp, and another 1/2" pipe acts as the return line to the freezer :slight_smile: