Could be good...could be bad

Hi all,

working on some last supply side items to get ready for rough plumbing and i have two ways to go -

situation:

it is a laundry and bath group on a first floor, full basement underneath

Choices:
there are places i can tie into existing copper inside the wall - which means
i'd need to pressurize my whole system (60 psi air) to pass -

or

i can tie all the copper together in the basement, pressure test, and then hook into the supply in an exposed area -

So, from a pro/service point of view, do I

Use the convenient connections in the wall, or run each supply to the basement area ?

what questions am i too inexperience to ask you all? (like turning off the valve to my boiler before attempting this)

can the current fixtures hold the air pressure? and if they can't does that mean they need servicing?

i have 1/2 pex tools, so i'd also consider running copper to the basement, and pex to a manifold -
i've got a thing about pex inside walls right now, but i think it is great in the basement to get to the
point where you want to go vertical..

neither solution is terribly difficult to implement - just looking for a pro point-of-view.
and the wisdom that comes with it...(it's reverence guys, not a** kissing!)

Many thanks, as always
Pat

The supply lines are generally much easier to configure than the drains and vents. I would first question what size branch lines are being tapped and how this will effect the other fixtures in the branch? As an example, a washing machine filling would take away much of the pressure/volume going to a sink on the same 1/2" branch line.

Water pressure in a house is commonly around 60psi so anything you have installed should have no issues with the pressure of the air test.

If you can run your new group(s) back to a 3/4" line (if you have them) I think you would be less likely to starve the existing system and create flow/temperature problems. I just did nearly exactly what you are describing and ran 3/4" PEX to mini manifolds (the all copper manifolds) and then 1/2" PEX home runs from the fixtures to the manifolds which serve the new back-to-back laundry/bath.

Thanks for the replies -

the laundry would be tapping into 3/4" lines already in the wall - the bath group would be tapping into a set of 3/4" lines in the basement.

seems my concern about pressurizing the whole system is no concern - - guess i should turn off the main valve also - should be interesting!

i have a well, and small bosch hw demand system - so if the laundry is running, washing hands is about all the system will allow!

already got some good advice on the dwv system - came out great! hopefully it will hold water!