I’ve got fairly weak water pressure throughout new home. Especially on Hot side. Been in the crawl space a bunch lately. Most of the plumbing underneath is newer pex, but plumbing was not replaced in walls, so pex 90s into steel pipe that rises into walls to feed all faucets. Been thinking those steel runs are likely becoming clogged with deposits limiting flow at point of exit.

But hooray, there’s more context:

The supply enters house with 1/2” steel for maybe 10 feet before transitioning to 3/4 pex for main run. Cold supply branches from the 3/4 line with 1/2 pex to hit those faucet risers. Hot line is 1/2 the entire way.

If I upsized that 1/2 main hot line to 3/4, would that boost flow at faucets? Or do the 1/2 pex and steel choke points at the end of each line negate that added volume at the end anyway?

TLDR: seems like larger 3/4 pipe volume in middle of cold water supply run adds water pressure at faucet even though beginning and end of run are 1/2 inch. Is that how water works?