I agree danmhippo, I wouldn't even think on using something that only lasted a day or two, been there, done that.
I know now that my top-off system in fail safe and I don't have to touch it at all except add kalk to the reactor and change the cartridges in the RO\DI unit. I can walk away from it for a month and not touch a thing.
I think we should try to use what works best and afford. My system is a little costly. The battery operated Solenoid is around 40.00, Liter Meter 250.00, Sipedon float switch 98.00, Geo Kalk reactor 100.00.
On those Kent solenoids and other pressure actuated solenoids, is there another line that has to run to the float valve or are they triggered buy the retern pressure from the water line running to the float valve?
Mark