Great forum. I am redoing my shower stall. It currently has seperate hot and cold controls and a showerhead from the early 1960's. If someone flushes the toilet or runs water elsewhere in the house while the shower is on, the temperature stays fairly constant but the pressure goes down.
I want to put in a handshower on a slide bar (probably Grohe Relexa Rustic 5). I am not sure what I need for valves. I have read that a Thermostatic valve help not only keep temp constant if someone else runs water, but helps keep pressure steady too. All of the Grohe Thermostatic controls say seperate volumne controls are required - expcept for the Grohmix integrated model. It seems odd to me (clearly I don't know what much about this) that you would use a Thermostatic control and then seperate hot and cold volumne controls. The shower is only 36" x36" so it seams like two roughly 8" trim units are a bit much.
What should I use in there?
There are basically 3 types of valves.
The first is the one you have... the old on/off with some basic adjustment. A little shocking when others use water.
The second and probably most common is the Pressure Balanced which adjusts hot and cold pressures to match with water usage and the resulting pressure fluctuations. Cost on these is about $100 on up and they will maintain +- 3 Degrees F approx.
The Last and The best is the Thermostatic this probably starts in price in the high $200 range on up. This physically measures the water temp and maintains it to about +- 1 Degree F.