PEX, Copper, or CPVC for separate shower (w/ rainhead) and tub?

[EthylOH]

Hi all,

New member here...

I've spent hours reading up on this topic, but I still can't seem to decide what my best approach is.

Right now, I'm in the middle of a full master bath remodel. My old shower/tub combo is fed with a 1/2" copper line. I have full access to all the plumbing from my basement.

In the process of demo, I noticed that I don't have shut-off valves for the bathroom water lines, so I put in two 1/2" sharkbite valves. (I can solder, but am no expert. I didn't buy sweat valves due to the fact that I don't want to run a torch 2" away from a wooden joist. Also, the sharkbites are in full view and are fastened in such a way that it is impossible for a catastrophic failure where water would be gushing out).

So my question comes down to this. What is my best approach to plumb in the shower valve, separate tub, and the sink?

If I use PEX or CPVC, wouldn't I have to move up to 3/4" with a coupling due to the fact that the ID is smaller than the copper? Or is 1/2" fine (I will be using a rainhead). How would I do this? Most PEX manifolds go from 3/4" to 1/2".

For reference, here are the fixtures that I bought:

Tub:
http://www.kingstonbrass.com/Center_Wall_Mount_Goose_Neck_Clawfoot_Tub_Filler_p/cc1t8.htm

Shower:
http://www.lowes.com/ProductDisplay...gId=10051&cmRelshp=req&rel=nofollow&cId=PDIO1

valves:
http://pro.moen.com/commercial/1-2-cc-connection-with-integral-stops/_/R-TPORTAL-ALL:8371HD

http://pro.moen.com/commercial/commercial-three-function-1-2-transfer-valve/_/R-TPORTAL-ALL:3360?next=SiteSearch.Link

 

[Jadziedzic]

Not to rain on your parade or anything, but are you aware that in the People's Republic of Massachusetts homeowners are not allowed to do *any* plumbing work - and can't even apply for a plumbing permit?

 

[Sponsor]

 

[Terry]

Normally for a tub shower running 1/2" PEX is fine. It kind of depends on how may things will be on at once.
You could bump to 3/4" over from the 1/2" copper while it is open though.

If you were running the Moen 8371 for the tub also, you would need 1/2" copper to the tub spout.

 

[EthylOH]

Normally for a tub shower running 1/2" PEX is fine. It kind of depends on how may things will be on at once.
You could bump to 3/4" over from the 1/2" copper while it is open though.

If you were running the Moen 8371 for the tub also, you would need 1/2" copper to the tub spout.

Only one thing will be on at a time in the bathroom. Either the tub or the shower.

Instead of a tub spout, I'm running the third valve to the rainhead.

So I'll have the standard shower head, a handheld, and then a rainhead above all of them. Only one can be on at a time. Do you see any problems with this setup?

And is 1/2" PEX okay to go to the tub? Is it because it's two separate lines feeding one spout?

Thanks in advance

 

[Jadnashua]

You do not want to use pex from the valve to the tub spout. You'd get a measurable, but small reduction in the fill rate of the tub if you feed it with pex verses copper to the valve(s). The magic design goal for piping water supplies is to limit the water flow velocity to a maximum of 5fps with the hot supply...that equates to about 4gpm with 1/2" nominal tubing. It's double that for 3/4" tubing. While you may be able to draw more than that, it's not a good design goal and can lead to long-term problems down the road.

 

[EthylOH]

You do not want to use pex from the valve to the tub spout. You'd get a measurable, but small reduction in the fill rate of the tub if you feed it with pex verses copper to the valve(s). The magic design goal for piping water supplies is to limit the water flow velocity to a maximum of 5fps with the hot supply...that equates to about 4gpm with 1/2" nominal tubing. It's double that for 3/4" tubing. While you may be able to draw more than that, it's not a good design goal and can lead to long-term problems down the road.

The tub spout is separate from the shower.

I made a very crude model of what I'm trying to achieve.

I guess what I'm trying to ask is what you would use to plumb this in:

I have full access from all sides.

Copper, CPVC, PEX, manifold, Tees, etc... what would you do?

Thanks!

 

[hj]

Since I do not use PEX or CPVC, my answer would be copper.

 

[Worksmarternotharder]

As far as sizing goes, CPVC is copper tube sized, and I believe actually has a slightly larger ID than copper.

PEX has a smaller ID and the fittings constrict water flow even more. If you want to stick with 1/2" and water flow is your main concern, I'd recommend CPVC.

As noted above, the difference will be small but it could be noticeable.

 

[Reach4]

As far as sizing goes, CPVC is copper tube sized, and I believe actually has a slightly larger ID than copper.

PEX has a smaller ID and the fittings constrict water flow even more.

CTS CPVC, the kind sold in stores and commonly used, is smaller ID than copper. http://www.engineeringtoolbox.com/cts-cpvc-tube-dimensions-d_1664.html

https://en.wikipedia.org/wiki/Copper_tubing

You are right on the PEX.

 

[Jadnashua]

The OD of copper, pex, cpvc are ALL THE SAME! Because the plastic tubing isn't as strong, it is the ID that is smaller. This is why you can sometimes use the same compression fittings on all of those different materials. Pex requires a reinforcement sleeve to be inserted into the tubing to allow a compression fitting, but the same one will work on copper because the OD is the same.

IOW, any plastic pipe will have a lower flow for equivalent lengths of tubing. Now, fittings do slow things down, and extraneous fittings should be avoided for multiple reasons. The beauty of pex is that you can often, and should strive for one fitting at the source end, and one at the fixture with no others in between. If the equivalent copper had numerous fittings, that added friction might offset its ID advantage.

 

[hj]

quote; CPVC is copper tube sized, and I believe actually has a slightly larger ID than copper.

If that were the case the CPVC wall would have to tissue paper thin, which is obviously NOT the case.

 

[CountryBumkin]

Only one thing will be on at a time in the bathroom. Either the tub or the shower.

Instead of a tub spout, I'm running the third valve to the rainhead.

So I'll have the standard shower head, a handheld, and then a rainhead above all of them. Only one can be on at a time. Do you see any problems with this setup?

And is 1/2" PEX okay to go to the tub? Is it because it's two separate lines feeding one spout?

Thanks in advance

It's your choice of course, but I wouldn't bother doing a rain head and a regular shower head together. The rain head is all u need. If you want more water force, the handheld spray head (mounted on track or bracket at head height) is the same as a shower head.