plumb tub/shower with cpvc in bath remodel

Looking for comments on plumbing a tub/shower using cpvc (almost everywhere). Does this sound reasonable: I'm planning on using 3/4" cpvc supply lines up to 3/4"x1/2" 90 cpvc reducing ells over to 1/2" cpvc male adapters into the mixing valve. Then 1/2" cpvc male adapters out of the mixing valve up (to the shower head) and down (to the bath spout) to 1/2" cpvc male adapters into 1/2" brass drop-eared 90 ells. Using the brass drop-eared fittings to make the shower head and bath spout attachments rigid.

Also, instead of using the 3/4"x1/2" 90 cpvc reducing ells to make the turn to the mixing valve should I use 3/4"x3/4"x1/2" 90 cpvc reducing tees and put a length (how long?) of capped cpvc or manufactured hammer arrestors above the tees?

Thanks for the help!

cpvc

You may have a problem with a "leaking" shower head unless you use copper, brass, or steel pipe down to the tub spout. CPVC has a much smaller i.d., so it creates a great deal of back pressure, usually enough to force water up theh shower riser even when the diverter is not operated.

hj said:

... use copper, brass, or steel pipe down to the tub spout...

Click to expand...

Is this the only place in the setup I described where I "should" use something other than cpvc?

cpvc

It is probably the only place you "should not" use CPVC, but for rigidity purposes I would also use something else for the pipe up to the shower head.

Thanks hj!

What about the use of 'home-made' or manufactured hammer arrestors?

Home-made air chambers are known to quickly become waterlogged and provide a location for water to stagnate.

A properly installed system with moderate pressure may not need any hammer arrestors, but putting some in is not a bad idea.

arrestors

Depending on the valve, most shower valves are designed so the water is cut off gradually so an arrestor would not be necessary.

Now after reading this thread: https://terrylove.com/forums/showthread.php?t=322 I'm just unsure of how to approach this as far as copper vs. cpvc. First off - I'm in the same boat as quantum as far as home improvement goes... "plumbing is the Final Frontier for me". So, should I take it that hj's comments mean that using cpvc up to the mixing valve is good, acceptable, or bad. I understand the reasons for not using cpvc down to the spout and up to the shower head. There just seems to be alot of debate over whether to use cpvc or copper in this setup.

pvc

I am neutral as far as using CPVC to the valve. I would not use it, but many plumbers do so with few problems.