Auto-Flush Kit works great! (just watch out if you have a touchless soap dispenser)
We installed the THU857 ourselves—it was very easy and works great. We disabled the auto-flush feature (via a button on the back of the remote) because we prefer to flush manually using the new button included with the kit to add to the remote control. This beats using the toilet lever. That said, the default setting is auto-flush if that’s what you want so it flushes when you get up off the seat and no button presses needed. And you can customize the delay to certain times to flush after you get up.
One minor issue: the instructions mention connecting the water feed hose to either a white or black port on the new 857 based on hose length, but there’s only a single black port. We just used that, and everything works fine.
A heads-up: the Toto S7 remote triggered our Simplehuman touch-free soap dispenser — likely due to overlapping infrared frequencies—causing soap to squirt unexpectedly. We replaced it with the Umbra Otto Automatic Touchless soap dispenser, which isn’t quite as sleek but doesn’t react to the remote.
Premier Bidets was excellent—low prices, fast shipping, and great customer service. They confirmed compatibility, answered questions about the auto-flush settings, and made sure we had what we needed. Highly recommend and would buy from them again.