We are a small associations of amateur brewers and we have a lot of great projects ahead. The one that concerns us in this discussion is the improvement of our fermentation process by buying 4 individual fermentations tanks. And we would like to use one (or several) Spark(s) to manage those tanks : but which set-up is the best according to actual Spark performances ?
Of course, more industrial regulatory systems exist but with less flexibility and scalability than Spark.
I’ve tried to sum up my ideas in the 3 following diagrams (the idea is to be able to manage the 4 chambers individually / The actuators are Motorized Ball Valves) :
As it is a significant investment, we must move towards the most flexible and robust solution. Every optimized or alternative set-ups will be gratefully welcomed !!
Option 1, while planned, isn’t currently possible. @Elco and co are working on a re-write of the BrewPi software to allow for multiple fermentors & other processes. I’m not sure where they’re up to with that or how long it’ll be though.
Option 2 should work if you install the BrewPi software using the Docker container method which I think is currently the preferred method of installation anyway. You’ll have to make sure each Docker container is set up to its own USB port for the BrewPi itself. That said, I think I’ve only seen people use 2 Docker containers on one RasPi. You might find running 4 pushes the RasPi too much in which case you’d need a slightly more powerful computer. I’d personally choose this option and use an old computer/laptop in place of the RasPi. That of course requires a little more Linux knowledge to get things up and running on something that isn’t a RasPi. But it’s worth remembering that an old laptop essentially has its own built in backup power supply. OK, that won’t stop your heaters/cooling going down, but you’ll still have your temp logging in the event of a short power cut.
Given what I’ve already said, option 3 is the “safest” option. It’ll definitely work. And given the cost of the RasPis against the cost of the rest of your equipment, you might find that the extra cost of 3 more RasPis is acceptable for a setup you can be completely sure will work.
You might be able to Pi Zero W as that has a network interface on it in the form of wifi. That said, it’s a less powerful device than the model 3. I’ve never used a Pi Zero before so I’m not sure if there’d be any other obstacles. You certainly couldn’t set it up by plugging a monitor, keyboard and mouse in as with the model 3. Maybe buy one first before buying any more? If it doesn’t work then you could always stick it in a drawer and tell yourself you’ll use it in a future project before forgetting about it
I’m not sure about directly driving the ball valves myself. I’ve never used the ball valves. Though I seem to remember they have have a return line that indicates weather the valve is open or closed. You wouldn’t be able to pick up that signal on the BrewPi without the control board.
