I bought an old house which needs to have the water supplies replumbed (It
has the old style butyl pipe, and I am
refinishing the basement)

I intend to run 3/4" Pex from the entrance (about half way down the 40 ft
length of the house)
in about 15 feet to where most of the fixtures are located,
then right angle turn and run about 16 feet drilling thru the 2x10 joists,
then right angle and run about 6 feet to the hot water tank.
Then run the 3/4 hot water pipe back parallel to the just run cold water.

Then I would tap off with 1/2 inch pex to the various fixtures between the
joists.

Question: I would have to cross 2 five inch furnace hot air pipes when I
drill thru the joists.
Will that be a problem with pex being near or touching the furnace
pipes ?

If so what is the best way to separate them

Thanks for any info

Ray