Setup for cooling of multiple Unitanks

I have the following setup today. The temperature control does not work, so I’m looking to replace the control part. I would like to learn if BrewPi could be my new control unit. I’m completely newbie so I need some help, please :slight_smile:

I have today:

  • 3 x 200L jacketed Unitanks each with a solenoid valve on the cooling jacket and a PT100 probe.
  • A control unit with a REX C-700 PID controller for each tank
  • a Lindr AS-200 cooler

The PID controllers are connected through a SSR that turns the pump of the cooler on, if any of the tanks need cooling and shots it off if none of them needs cooling.

If possible I would like to change the 3 PID controllers to a setup that I can both monitor and control online as I’m not in the brewery every day. I would also like a system that is easy to tune in and balance. My current controller undershoots the temperature with several degrees and I can’t get the settings right.

I would like to keep the functionality that stops the pump in the cooler if none of the tanks need cooling.

Can anyone help me to understand how I can setup the temperature control using BrewPi, and what I would need to buy to get it running. And will a system based on BrewPi fulfil my described requirements for a system?

Apart from the PT100 sensors, this can be implemented using Brewblox. PT100 support is some months out, and may be further delayed if supply chain shortages worsen.

Assuming a OneWire-based (temporary) solution is acceptable, an estimate for a basic setup would be:

  • 1x Spark Controller
  • 1x Spark power supply (12V DC, or passive PoE)
  • 1x Server (Raspberry Pi, Synology NAS, or Linux-based computer)
  • 2x OneWire GPIO module
  • 3x OneWire sensor (more if you want to track room temp or glycol temp)
  • Electrical wiring, ethernet cables / wifi access, etc

The Spark controller can run PID heat/cool control for all three tanks, along with control logic for turning off the pump when unused.

The server stores history data, and hosts a browser-based UI for controlling and monitoring your setup. This is done purely local, and does not rely on a cloud-based service.

If you wish to access the UI while not at home, we have a guide for setting up secure remote access to your home network.

The PIDs are initialized with sensible defaults, and can then be tuned. This does require a working knowledge of PID control theory. We’re happy to assist here if required.

If you have a Pi or a Linux VM at hand, you can install the Brewblox software, and use the Spark simulator to get a feel for the available configuration.

Hi Bob,

Thanks a lot for you reply. I’ve tried to put together a shopping list. I can’t find a Spark Power Supply in the shop. Is there one or is it a standard that I will need to find someone else?

Other than that, does the following look right?

Due to the variety in use cases, we’ve kept the power supply form factor generic. The OneWire GPIO module does not have a barrel jack, but has +/- pins for 12V or 24V DC power.
Alternatively, passive PoE using the ethernet port on the Spark itself is supported.
You only need a single power supply: a power supply connected to any of the modules will be used by all.

In your shopping list, there are two GPIO modules, but only a single module enclosure. Is this intentional?

Note that DIN rail connectors and enclosures are mutually exclusive. While still useful to have, if you’re certain that you’re mounting on a DIN rail in an enclosed space, the additional enclosures are not required.

DIN rail connectors can be attached to both the Spark, and the GPIO modules, and all modules can be attached simultaneously. You can choose to use 1, 2 or 3 connectors to attach your controller + modules to the rail.

Hi Bob,

Just a clarifying question.

As far as I understand, it is possible to control op to 8 outputs from the basis module of the Spark 4 if they use minus from the power supply. Is there a need to buy the additional GPIO module in that case? As mentioned I have 3 tanks and I only control cooling - not heating.

I missed the point about not heating. You’re correct: if you can get by with 8 GPIO pins and 4 OneWire slots, you only need a single GPIO module.

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Hi Bob,

I placed the order and will be receiving the equipment today. Just to make sure that is will have everything for installation I have some additional questions:

Control of solenoid valves:
Each tank has a solenoid valve on the intake of the cooling cap. It’s a 24V normally closed valve. Do I need an SSR between the BrewPi and each tank to control the valves?

Control of pump:
I have an SSR with low voltage as input and 230V as output to control my pump today. Can I use that to control the pump in this new setup?

The pump, and 24V solenoids are both supported, but with some remarks:

GPIO has a per-module toggle for 5V/{power supply voltage}. Directly powering your solenoids would mean putting 24V on the pump SSR input. This may or may not be acceptable, depending on the SSR.

If GPIO is 5V, the Spark can be exclusively powered using the USB-C port. This may be convenient if the Spark is mounted next to the server.

If the pump SSR input supports 24V, it comes down to what is more convenient: putting in SSRs, or giving the Spark a 24V power supply.

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Great. I already have a 24V power supply, so I should be good to go :slight_smile:

Thanks for all your quick support