Automated/closed system HERMS brewpi

So I’ve been watching Elko’s thread over at homebrewtalk, where he’s planning a brewpi-based partially automated herms system. I’m watching intently because I’m in the market to buy a new home brewery, and I’m trying to decide between something like a Kal-clone, or this. If I go with this, how do I incorporate volume / level sensors? The other part is I want to buy kettles from Stout, which are all pre-welded. If I don’t think about this now, I’ll need to make holes in otherwise beautiful welded kettles, and this I’d want to avoid.

Thoughts anyone? Are the volume sensors really needed? Could I avoid using volume sensors if I use a lauter grant? Of course I don’t want to overflow anything or run my pumps dry.


Volume sensors will not be a needed option, just a premium upgrade.
I still have to prototype mine and I don’t want to stop brewing until I have them ready.

Without the volume sensors, I’ll just have to watch the volumes manually. A float sensor could also work, it is just less flexible because you cannot measure volume, only fill up to a pre-set target.

Those Stout kettles look nice. Don’t make holes when you don’t need to. I don’t think buying the Stout or an undrilled pot will make a difference regarding the volume sensors: they both do not have holes for it.

I suppose there are a few ways to accomplish a system that is intelligent to the amount of fluids are contained in the vessels. I know that someone once mentioned flow sensors to you, but you brushed that off. What are your feelings on flow sensors, and why do you think dual pressure sensors are better? I ask about the holes for those since I can have Stout weld fittings onto the kettles if I ask, but I’d need to understand beforehand if it’s the right idea. I know I’m getting ahead of you but I’m as excited about a new brewery as you are, I’m sure.

My problem with flow sensors is that the for example cannot measure boil-off.
Most of them have also have a sort of propeller inside and just count revolutions. Having that propeller inline will cause issues with small bits in the solution and limit the flow. They might work to measure the clean water coming in, but after that, you will have to track where water is going.

Things are easier if you have a sensor in each kettle that tells you the absolute volume, instead of a flow rate.

Ok I understand now what you mean about the drawbacks of using flow sensors. So might you tip your hand and let us know what you had in mind for a volume sensor in the kettles? There are so many ways to accomplish this, but few are suited to something like a mash tun that will have grain and liquid in it. Have you ever seen these so-called eTape liquid measuring sensors?

I would like to experiment with freescale pressure sensors on a tube going down into the beer. These will be connected to an aquarium pump to ensure that the tube is always full of air. The beertroller guys experimented with this.

I hope we can make it accurate enough to do a pressure (water column) measurement at two known heights and deduce the density of the liquid from that.

My HERMS implementation plan is to use a stainless float valve (ala Blichmann autosparge, but sourced from Aliexpress) to maintain the desired fluid level in the tun and vary the pump outlet valve to reach the desired HERMS outlet temperature. Step mashing can be accomplished by setting the HLT to the next step setpoint in time for it to ramp before starting the step. Though if the system is responsive enough, the HLT ramp could be accomplished concurrently with the mash step.

As far as volume measurement goes, a small floating magnet in the sight gauge and a pickup of some sort stuck on the outside of the tube would be simple, easy to convert to a digital value, and have the effect of insulating the volume measurement from the rolling surface of a BK.

I assume the reason for volume measurement is to control boil-off in order to hit the desired post-boil volume. Another solution would be to enter the pre-boil volume and desired volume manually and calculate the energy required to reach the desired volume over the prescribed amount of time then set the PWM duty cycle to achieve those results. This would require measuring the Voltage and Amperage going to the coil and using those numbers to calculate the wattage which would be used in a loop to continuously vary duty cycle throughout the boil. Sensors for atmospheric pressure, humidity, ambient temperature would help provide more consistent results as the energy of vaporization varies with those parameters.

Do you have a alpha herms software for herms setup available for the spark?

@Elco seems planning to implement the system described on the BrewTroller homepage.

BrewTroller is not in business anymore, but they seem to plan a kickstarter campaign for a re-launch…

Here’s a rundown of various process fluid measurement techniques. Just have to determine what would work best.

would it be possible to rewrite todays code, so that we can get a brewing pid controller?

This way we can start using the Brewpi for brewing at once, and implement the automated system when it is ready?

That is exactly what I am doing. Controlling the valves will come later.

so there is possibilities to have 5-10 minutes steps in the temperature profile today?

Yes, you can use a decimal point in the days.
It just needs a small code change to allow you to enter 10m instead of 0.007.

So if anyone is looking for a small javascript challenge…
The profile is stored with datetimes, so it is just converting the string 10m or 2h10 to a date in Javascript and putting it in the last column.