PHSI PW1R water cooler LCD hack
Our workplace recently got some fancy-pants water filtration system (the PHSI PW1R) that takes tap water and filters it, ozonates it, then cools or heats it. It’s actually pretty neat, makes for some nice fresh and ice cold water (or hot water for tea, if that’s your bag). The unit itself is pretty simple. Press a button for cold water, press two simultaneously for hot. It also has a few other buttons – one to cycle through the messages on the LCD display, another to run a system test, and some unlabeled button behind a graphic that doesn’t appear to do anything. The LCD is a standard character LCD with a nice blue backlight (ah, geeks and their blue blinkenlights).
By default, the LCD cycles through some readouts showing unit consumption in gallons, some jazz about “ATS – Auto Tank Sanitation (TM)”, and “PURE WATER!” (exclamation mark included). Of course, I want to change these to our own messages now. 
The unit has no serial ports that I could find (and I don’t think the boss would appreciate me disassembling the new water cooler to find one deep inside). After tinkering with powering up the system while holding different button combinations (and discharging several spurts of liquid in the process!), it turns out that holding down the “Display”, “Test”, and top of the two “Hot” buttons yields a management interface. From here you can change a few items, including ozone injection settings — and of course, the display!
You can scroll through the menus (and options) with the two “Hot” buttons. Items can be toggled on and off with the “Test” button, and selections can be made with “Display”. Let’s just say that it takes an eternity to set messages of any length, and you must pad messages by hand in order to center them. Now I really wish this thing had a serial port. Oh well…
Happy hacking!