So my wife and I recently had our bathroom renovated, and as part of that renovation, we had the Grohflex rough-in and the Grohe Grohtherm 2000 valve/trim ("Authentic", if it matters) installed. The larger shower/spout selector lever that's closer to the wall works great- it diverts the water from shower to tub spout just fine, and regulates the water pressure on either one, depending on how far to the left or right it is moved.

What's weird to me, is that the temp lever (the smaller, outer lever) seems to also regulate the pressure- if the larger lever is set all the way to the left for the tub spout, then putting the temp lever to the left for cold water results in relatively anemic water flow. The pressure rises as we set the temperature higher, so that when it's set for fully hot, water is coming out as fast as it can.

Correct me if I'm wrong, but isn't the way this SHOULD work is that the selector lever should regulate the pressure entirely, and the temp lever should just regulate how the two sources (hot/cold) are mixed, without changing the pressure?

It's not a huge deal; how often do you fill your tub with cold water anyway? But if it's installed wrong, I'd like to see it done right.

The best I can come up with is that they didn't open the cold water service stop all the way, or maybe there's some crud in the line. Does this sound reasonable?



Links to the actual hardware pages:

Rough-in box:

[www.grohe.com]

Actual dual-function pressure-balancing valve:

[www.grohe.com]

possibly the trim is not installed correctly? grohe is a good quality valve but they are not know for being installer friendly. multiple trims fit the same rough in valve and the installation directions usually show you pictures rather than detailed verbal instructions.