The Auto Top Off I'd like to make.

[minfinger]

I must give credit to Weatherson for the original idea.
Rob, this was the auto Top I was telling you about. I syphons or drains out to the tank. The Kent Float valve is connected to the Kent Selinoid kit on the RO Unit and once the chamber empties, then the solenoid opens when the pressure is released. I think he siad he was using a 29G tank, but you can sue whatever.

http://home.comcast.net/~joe.michelle/images/240_construction_photos/157_top-off.jpg

http://home.comcast.net/~joe.michelle/images/240_construction_photos/158_top-off2.jpg

http://home.comcast.net/~joe.michelle/images/240_construction_photos/159_chamber.jpg

http://home.comcast.net/~joe.michelle/images/240_construction_photos/174_3rd_chamber.jpg

http://home.comcast.net/~joe.michelle/images/240_construction_photos/175_reservoir_front.jpg

[skipm]

Pretty neat idea. You would have to make sure that you had a sensitive enough check valve to allow the slight pressure that would build up when the tank was refilling to release. Of course if you just wanted a way to have the RO unit keep from cycling too regularly you could build a make up tank with a large surface area, this way 1/2" of water would be a large amount. You would also have to have the shut off solenoid for the RO unit so it wouldn't keep wasting water when the tank is full.

[minfinger]

He siad that this check valve was the best he'd ever seen and didn't cost that much.

http://www.microchek.com/html/check_valves_.html