Is any special shower faucet valve necessary for this unit

"This unit". Are you talking about a specific brand and model? If replacing a shower head, they just usually screw on the spout. If you want a regular shower head AND a handheld, you install a diverter on the spout. What are your plans?

Hi John

You can install a diverter external to the wall on the SHOWER ARM to control regular shower head VS hand-held shower, or you can install a 3-port diverter internal to the wall to allow use of regular shower head only, hand-held shower only, or BOTH regular shower head AND head-held shower head at the same time. There is quite a bit more work/parts/labor involved with the latter option.

Let us know what you are thinking here...

Mark

Yes, we need to know make and model to know for sure. Most after market models do not need a new valve. the diverter is built into the unit. It activates when you press/squeeze a button on the hand held part.

You will have to use diverter to switch between two shower outlets. Diverter can be a separate valve on the wall or it can be built into the main temp/volume control valve. HansGrohe makes such multi-port shower valves and also few domestic brands offer this same option.

You can also consider installing just hand-held, mounted on adjustable height rail. This is a very popular option. In this configuration, you use regular shower faucet (valve), with single outlet ( wall union) and rail. Hand-held than acts as regular shower head and hand-held. Best such set up is by Grohe

Hope that helps

Milo