Pex question.... repipe....

house is copper, built in '62.
raised floors, crawl space.

sewer is cast iron, 3" main. pretty good condition, aside
from the ficus tree in the front yard that is in mortal peril
if it screws with my sewer main. i'm largely leaving it alone,
with the exception of a toto in wall toilet.

now, the copper.... not in very good condition. southern
calif water, never been a water softener on the house,
so, it's time to repipe. T's and couplings are weepy, with
lots of evidence of seepage.

1" feed from the meter, 3/4" copper from shutoff on the front
of the house.

now, the strategy.... i'm going to use a manifold for both hot
and cold water, located above and in front of the water heater,
not blocking it. individual 1/2" pex for each device, with a ball
valve on the manifold. pex and fittings are uphonor, with a
milwualkee pex tool for connection.

no tees or splices except at the manifold, and the connection
to the device. stubs thru the walls in copper.

now, the questions... should i put 1" pex instead of 3/4" to the
cold manifold? manifolds are 6 port, with 3/4" at one end, and 1"
at the other, so i can go either way.

i have 10 cold, and 8 hot taps on the manifolds. ball valves on
each tap, in case things don't go well. uphonor ball valves for
the shutoffs, seem to be made of unobtanium, judging by the
price.

as i was going to go under the house in 1", i want to run 1" all the
way thru the house underneath, out to the backyard. there is a pool,
and i want a full 1" to the pool fill.

so... the questions come to these:

3/4" or 1" to the cold manifold? hot obviously is 3/4" off the heater.
if i use an 18" flex connection to the water heater, can i go directly
to pex?

was going to use 1" brass schedule 40, cut and threaded, thru
the wall into the crawl space, then transition to pex inside.
is this acceptable?

this is really stupid to ask, but i don't know...
for the pex run to the pool fill, do i have to change to change to
pvc to run bedded in sand under the pavers around the pool, or
is pex legal in such a situation? i was going to use schedule 80 pvc,
but after looking at the pex, it seems pretty indestructible.

for gluing up domestic water in pvc, what's best? christie's red hot blue glue and
primer, or is there something better?

anyway, thanks for any feedback.

quote; for the pex run to the pool fill, do i have to change to change to
pvc to run bedded in sand under the pavers around the pool, or
is pex legal in such a situation? i was going to use schedule 80 pvc,
but after looking at the pex, it seems pretty indestructible.

Nomrally, you do NOT need anything larger than 1/2" PEX to the pool filler, and NOWHERE in the discussion about the pool filler do you mention the REQUIRED antisiphon backflow prevention valve, which MUST BE located at least 12" above the pool's deck, unless the pool fill is an above the pool nozzle.

hj said:

quote; for the pex run to the pool fill, do i have to change to change to
pvc to run bedded in sand under the pavers around the pool, or
is pex legal in such a situation? i was going to use schedule 80 pvc,
but after looking at the pex, it seems pretty indestructible.

Nomrally, you do NOT need anything larger than 1/2" PEX to the pool filler, and NOWHERE in the discussion about the pool filler do you mention the REQUIRED antisiphon backflow prevention valve, which MUST BE located at least 12" above the pool's deck, unless the pool fill is an above the pool nozzle.

Click to expand...

fair 'nuff.. i didn't mention it, 'cause it wasn't in the scope of what i needed to know...
there will be a backflow preventer... i just wanted to be able to fill the pool quickly,
assuming any water is left in calif to fill it with.

the pool has a bit of unconventional plumbing, so i'm not using a standard auto filler.
the pool has 8 gate valves arranged in a "H" manifold, so the pool and attached jacuzzi
can be configured a number of ways.... normal heating and filtering mode is, water is drawn
from the jacuzzi bottom drain, and jets, filtered, heated, and returned to the bottom drain
in the pool, where it heats from the bottom up.

the water spills over the wall separating the jacuzzi from the pool, into the jacuzzi, which
causes any surface leaves and dirt to end up spinning in the jacuzzi, where they collect
in a corner, and one scoop with the net cleans the entire pool.

i have a 400k btu heater, with a cartridge filter, and liquid acid and chlorine feeder to
maintain proper PH and chlorine levels.

in jacuzzi mode, water is drawn from bottom drain, filtered, heated, and returned to
jacuzzi jets. one of the jets is a dummy, and feeds pool water to a 2" standpipe near
the pool equipment, with a proximity sensor to sense the level, and open a solenoid
valve, when the pool is circulating in heating mode. this lets me maintain the water
level in the jacuzzi within about a half inch.

the purpose of all of this is to allow me to heat the pool for a reasonable amount of
money. i can turn on the pool heater friday morning, and the pool will be heated about
20 degrees in about 5 hours, and be warmer at the bottom than the top. you can turn
off the heater, and it'll stay comfortable for the weekend. 8 hours running will put the
entire pool at about 92. but... it's a 2" gas line feeding the heater, and it sounds like
a big block with a 4 barrel when it lights off... a rumble that sounds like a lot of gas is
getting burnt.

but my question is.... is my manifold and drops adequate with 3/4" or do i need 1"
to feed them?

thanks for taking the time to reply....

On the cold side, I only run a one bath home with 3/4"
Add a second bath, and it's 1"

The hot can be 3/4"
You don't have hot to the outside bibs or to the toilets.