Is it worth running 3/4" PEX?

Howdy Y'all,

I am adding a new bathroom (toilet, shower and lav) on the second floor of a VERY old house. (1850's) At some point in the recent past, the previous owner had all the plumbing redone in 1/2" PEX. (A few lengths of 1/2" copper still exist in a few places). The whole house is 1/2" starting from the precharged tank and hot water heater all the way up to the main bathroom on the second floor. (And the main floor bathroom, kitchen, washer)

My question is this: to get H+C upstairs to the new bathroom I plan on tapping off from the existing 1/2" lines in the basement, and I don't know if it's worth going to 3/4" PEX for a 14' vertical run, then back to 1/2" copper to make the connections for the fittings. Will there be a noticeable difference in volume / pressure by using a 3/4" section? Or should I just stick with 1/2" throughout?

Thanks in advance...

M

Don't think so in that long of run. Upsizing a pipe like that only helps on really high or long runs, not sure where the trade off would be, but not at 14'. However for a full bath upstairs you should run to a 3/4" source and run 3/4" especially in PEX. Unless you run a home run system off a manifold.

Before someone else says it, watch for lawsuits on some PEX systems. Wirsbo is by far the most proven system out there.

My unprofessional thoughts are don't bother unless you have a 3/4" supply line somewhere you can tap into. Note, though, that 3/4" pex is only a little bigger ID than 1/2" copper. One of the advantages, though, is that it has less friction and fittings so a smaller one can end up with the same flow as equivalent copper.

Thanks guys.

I guess I'll go with 1/2" PEX then. The rest of the house is Wirsbo, so I'll stick with that.

As for a manifold, I was thinking about having a manifold in that new bathroom, then spur off to each fixture. This way, the only PEX connections would be at the fixture and at the manifold; no underfloor connections or in wall connections. I'd feel more comfortable knowing that all connections are easily accessible. Good idea?

Cheers,

M