For posterity and anyone stumbling into this topic, I threw together a very similar web app to help winterize an irrigation system controlled by Rachio using an attached air compressor. It runs entirely in your browser and does not send your data anywhere other than Rachio.
I suggest using this on a computer (not phone) which is set to not go to sleep. Feel free to submit issues / suggestions in the GitHub repo (preferred) or here, though I can’t promise I’ll be able to make updates very often.