Okay to use Pex B for a new addition?

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I am down to the last part of my room addition; the supply lines. I have always used copper, but my friend has a Pex B crimp tool and I know it would be a huge time saver, plus less time in the crawl space. I currently have 3/4" supply coming into the house that feeds the water heater. Every fixture in the house is supplied with 1/2" copper. I measure 80 PSI on a outside water spigot and the water pressure in the existing second floor showers is great; one of which is a dual shower head.

The new addition is a full bath with a dual shower head as well: "1.75 gpm maximum showerhead/handshower flow rate at 45 psi". I planned on tapping both hot and cold off of existing 1/2" copper, which would then travel 15', then split via a tee and supply the vanity and toilet in opposite directions. Past the vanity, in the same direction another 10', is the shower, then up to the valve. To be safe, should I just sweat with copper or will Pex B give me the good performance.
 

Reach4

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You usually want 3/4 pex for the cold before it splits to tub/toilet/lav. You want 1/2 for hot. Ideally you would use 3/8 if only carrying water to the lav, but 1/2 if carrying water to both tub and lav. Very few use 3/8, because it adds to the expense. The point of 3/8 would be to get hot water to the lav quicker.

PEX is supposed to be supported every 32 horizontal inches.
 

John Gayewski

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I think before I did what you are thinking, I would see what my dynamic pressure measured. Meaning while the water is running how much pressure is measured. You'd have to make a test rig.

There's not a 3/4" line you can get into?

Your gonna have a long wait for hot water it sounds to me.
 
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I have decided to run diagonal lines to reduce the waiting time for hot water. When running through joists, should I use abrasion plugs?
 

John Gayewski

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I have decided to run diagonal lines to reduce the waiting time for hot water. When running through joists, should I use abrasion plugs?
Yes, if by abrasion plugs you mean what I think you mean. I guess I haven't looked to see what they are actually called.
 

Fitter30

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Hot water to shower try not to come off the side outlet ( bull) of a tee for less pressure drop. one isn't bad but have three or four is another story.
 

Jeff H Young

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Breaking the unwritten rules of angling pipe isnt a big deal diagnol might not look the greatest but if you want to do that and eliminate 90s and length is shorter its your house Boss!
 
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Breaking the unwritten rules of angling pipe isnt a big deal diagnol might not look the greatest but if you want to do that and eliminate 90s and length is shorter its your house Boss!
yeah... I'm OCD, but I could really shorten the run. It's in a unfinished part of the basement that will never be finished so I figure why not.
 
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Hot water to shower try not to come off the side outlet ( bull) of a tee for less pressure drop. one isn't bad but have three or four is another story.
I plan on 1/2" copper tee, to pex, then straight run to the shower with 1/2" PEX. I could always replace with 3/4" if the flow or pressure is off.
 
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Yes, if by abrasion plugs you mean what I think you mean. I guess I haven't looked to see what they are actually called.
I have decided to definitely run the hot run diagonally. I was hoping to drill the holes diagonally as well, but that is not looking like an easy thing to accomplish. I wanted to drill them at an angle so that I could use insulation pipe to protect the PEX. How necessary is this? I see every answer under the sun on forums.
 

John Gayewski

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How necessary is what? Insulation? It's not necessary, but would be better. Protecting the pex? It will likley take a long time for the pex to wear a hole in it from pennatrating wood. I'm not really sure it would wear a hole in it, but I would sleep better knowing mine was protected.

I check mine in my basement every once in a while to see if I can see signs of wear from going through a wood floor with no protection. But at work I always protect it.
 
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