The differential pressure based volume sensor is kind of tricky to use and have a lot of “moving parts” so we designed a volume sensor based on the fermenter weight instead.

The scale is a standard bathroom scale capable of 180 kg that is stripped of all electronics except for the 4 pressure sensors that is connected to a HX711 break out board that in turn communicates with our fermenter computer (RPi) like everything else 🙂 The raw pressure data is then communicated to HASS for conversion to weight.

In HASS we can set (current) SG that in turn gives us volume from weight. We can also tare the scale and put in offsets if we mount accessories (with known weight) on the fermenter after tare.

The pressure sensors are extremely linear (as physicists we loves an R-square of 1.000) and are very stable over time.

We can actually use the weight of the fermenter as a measure of SG, not absolute SG but relative any way.

The sudden drop in absolute weight is due to krausen leaving the fermenter through the blow off tube 🙁 But the weight is still usable as a measure of fermentation activity!