PEX size to use from supply to valve to diverter to fixture

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El Jefe

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I'm re-doing a shower. I have 1/2" PEX supply lines (hot and cold) coming into the bathroom. This currently coverts to 1/2" copper to a single valve and shower head.

I want to leave the 1/2" supply in place, but replace everything else. I bought all Hansgrohe valves and heads. The valve has 3/4 NPT threaded ports, and the heads have 1/2". I'd like to use PEX, because I figured it'd be easier. Since the valve is 3/4", I bought some adapters to go to 1/2" crimp-style PEX. Diagram is here.

The tubing looks small, and I understand it has a smaller inner diameter than the 1/2 copper.

Should I go with 3/4" PEX instead between the valve and diverter and b/w the diverter and heads, then downconvert to the 1/2" at the end fixtures? Or, is 1/2" Ok, given that I'm planning to keep the supply lines? FYI, I'll have a handshower, regular shower head and a rain shower (I realize I won't be able to use them all simultaneously). What would give the best result with the given supply lines and valves?

Here are some pictures - I appreciate any advice you might have :):


Supply line:

IMG_2683.jpg


The current setup, with compression fittings between 1/2" PEX supply and 1/2" copper:

IMG_2684.jpg


The new Hansgrohe valves with sharkbite coupler (which I'll use to connect supply to new 1/2" PEX), and the adapters (3/4" NPT to 1/2" PEX crimp-style, not compression):

IMG_2685.jpg
 

Terry

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Uponor as it's now called can use sharkbits, but not most other PEX fittings by other brands. Sizing on the inside is a little different.

If you are using PEX for a diverter, you better secure it well in the wall. PEX gives no support at all. That's why I mainly run copper for the valves, even if I'm running PEX to that location.
 

El Jefe

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Uponor as it's now called can use sharkbits, but not most other PEX fittings by other brands. Sizing on the inside is a little different.

If you are using PEX for a diverter, you better secure it well in the wall. PEX gives no support at all. That's why I mainly run copper for the valves, even if I'm running PEX to that location.

The diverter valve just has the two holes for fasteners. I was just planning to use those to secure it to some blocking between the 2/6 studs. But, at your recommendation, I'll do some more searching to see if there's a better way to secure it, or I'll reconsider using copper. This valve is heavy.
 

El Jefe

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Would going with 3/4" PEX in between the valves and diverter and shower heads be better than 1/2"? Better performance (pressure), or even better supporting structure to the diverter?
 

El Jefe

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Uponor as it's now called can use sharkbits, but not most other PEX fittings by other brands. Sizing on the inside is a little different.

What's the best way to connect the Uponor to the Lowe's variety PEX B?
 
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Terry

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What's the best way to connect the Wirsbo to the Lowe's variety PEX B?

The two don't convert. You would either use a sharkbite that uses the OD of the tubing, or you would use a Uponor fitting installed with expander, perhaps a male adapter and then a female to that from the Home Depot tubing.
The Sharkbite is going to be the easiest of the two.
I keep Uponor on the vans, with the Milwaukee expander.
 

Jadnashua

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3/4" valves cost more than 1/2" valves, and with 1/2" PEX supply lines, won't do anything more for you except take extra money out of your pocket. They only provide a benefit if you can supply them with larger pipe all the way back to the main supply. Usually (there may be exceptions), the trim choices between the two (1/2" or 3/4") are identical. 3/4" PEX is only slightly bigger than 1/2" copper on the ID, and may be better to run from the copper supply lines than 1/2" PEX. But, on a single shower head, 1/2" PEX can flow more than any single head (as long as you have not modified it) can use, so you should not see any difference in performance. The larger valve and supply line comes into its own when you are requesting a greater volume, like two or more heads running simultaneously.
 

Vegas_sparky

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You'll have the volume from mixed hot and cold. I'd go copper between the two valves, and pex to the heads. It will help stregthen/support the two valves, and you'll know that piping won't be a restriction.
 
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El Jefe

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You'll have the volume from mixed hot and cold. I'd go copper between the two valves, and PEX to the heads. It will help strengthen/support the two valves, and you'll know that piping won't be a restriction.

I picked up the tubing today. Took me about 45 minutes of staring to figure out what I thought I needed. I flipped back and forth on what size, material, etc.

I ultimately decided to use 3/4" PEX from the supply to the valve (not all the way back, just to the supply lines directly under the floor). I realize this probably was stupid and unnecessary. After that, I'll do as some have suggested and use copper between valve and diverter. I went with 3/4",simply because the ports on both ends are 3/4", and I figured part of the reason for it is rigidity, so the larger copper couldn't hurt. From the valve and diverter to the heads I'll use 1/2" PEX with crimp rings. The rain shower will come out of the bottom port of the main valve, so I got two 90 degree PEX guide curve things so I can loop it 180 degrees upward into the attic without having to cut the PEX and create an elbow.


For the supply lines, I got a sharkbite that will convert from the 1/2" PEX (hopefully, since I wasn't sure how to determine if it would fit the Uponor or not) to the 3/4" PEX. As I said above, I'm guessing the 3/4" wasn't necessary, but the little 1/2" PEX looks so tiny. It's like looking at a .22 caliber barrel compared to .40 S&W. It just looked powerless, so in a moment if irrationality, I grabbed he 3/4" PEX for that run. If it was a waste of money, I can live with that. But, if it will actually degrade the performance, please do let me know and I'll go back and get some more 1/2" PEX and connections.

Thanks for your help.
 
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Jadnashua

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3/4" pex should not be a problem, and will be easier to deal with a 3/4" valve since you don't have to convert the size first for the fitting. That pex will maintain the volume available from your 1/2" copper supply line. Keep in mind, that pex gets even smaller when you insert a fitting into it, but short sections do not have as much effect as a long section of pipe that is smaller (but it is still a restriction). The 3/4" valve was probably overkill for one head running at a time, but would be welcomed for more.
 

El Jefe

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Thanks. I probably would have bought a 1/2" valve, but as far as I could tell the Hansgrohe iBox is only in 3/4", and it's their universal system for all their valves and trim.

I was leaning towards a Moen set for a while that had a 1/2" size.

At any rate, I'm glad the short run of 3/4" PEX won't wreck anything.
 

El Jefe

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So, hopefully this is what you meant. I first soldered the copper tube and the threaded fittings, then screwed on the valves.

image.jpg
 
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