I just got my Hansgrohe single-handle pressure-balance trim, and I have to rave about the engineering on this thing.
First, the iBox is genius. One rough-in can be used with pressure balance or thermostatic cartridges. Change your mind? No need to rip out your tilework. And, of course, the iBox is a full 3/4" and not a wimpy 1/2". It also comes with a plastic shell to direct any leaks out of the wall cavity, to save your framing. Smart.
Then, the pressure balance cartridge. Unlike other manufacturers, this one does NOT require a "double ell" or "twin ell" when used with a tub diverter spout. Of course this information was hard to come by. I couldn't find any information online except the Hansgrohe FAQ that states that one of their obsolete valves doesn't need a twin ell. I finally had to email Hansgrohe support to confirm that the new models also do not need a twin ell.
Not needing a twin ell is nice, because a twin ell restricts flow. Check this out:
Internally, that thing has a pitiful 1/4" opening for the tub spout! A lot of it has to do with preventing the shower head from spitting water when you're filling the tub for a bath. Too much flow backs up at the spout and gets pushed up the shower riser. That's because a twin ell depends solely on the water's velocity to not turn 180° and go up the shower riser. Do anything to kill that velocity, like open up the tub filler passage, and you get unwanted shower flow. So your tub must
Instead, Hansgrohe uses what appears to be a venturi. Looking at the internal passages and orifices, I can see a small hole for the upper shower output intersecting the increasing-diameter lower tub spout output. With the spout diverter open, air could actually be entrained from the shower head and into the tub spout (that's a venturi's purpose in life, after all). So now your tub filler can be full flow without risking water backing up to the shower. In-freakin-credible genius there, guys.
Now, before I start to sound like a Hansgrohe shill, I still have some gripes. Like, not just Hansgrohe, but for just about any
valve except Moen, it's really hard to find out how to operate them. I searched and searched Hansgrohe's website but could not find if their pressure balance was pull-on push-off twist-temp like Moentrol, or if it was more like Positemp, or what. Not until I actually got the thing in my hands did I find the documentation it came with that showed 6 o'clock as off, 5 o'clock as cold, and 3 o'clock as hot. Such a short throw is gonna make it hard to dial in the right temperature, vs say Positemp which has a much wider range of travel. Not only is a short throw annoying, it's doubly annoying you can't find that information until after you've already bought the valve and it's too late to change your mind.