Pressure problem

[Cdnkyle]

I'm helping a friend this weekend with a plumbing project. He is switching his house from galvinzed pipe to pex and installing a tankless electric hot water heater. He is also incorporating a manifold.

He has been working at removing the pipe evenings last week, and has 3/4 pex going from the meter to the manifold.

The problem is when we hooked the shower toliet and sink up to the manifold, there was no pressure. The showers woul barely work. A trickle if you turned on both tapes and flushed the toliet.

He had decent/normal pressure before.

Here is what I think the problem is. It's 1/2 inch coming out of the meter, he goes from 1/2 to 3/4 for about 30 feet to the manifold. So far only the sink, tub and toliet are hooked up to the manifold.

Did he lose all the pressure going from 1/2 to 3/4 at the meter? He thought he would gain the pressure back when the manifold went to 1/2 inch.

Would going 1/2 from meter to manifold fix the pressure?

Let me know if pictures would help.

 

[IFIXH20]

Water service should be a minimal 3/4'' from the meter to the home. Post pics of what you have.

 

[frodo]

pressure does not change. if your city is delivering 50 psi. inless you put booster pump it is 50 psi.

what does change when you change pipe sizes is volume.

your friends home WAS fed with a 3/4'' galvinized pipe. that is 3/4'' ID.

you guys, decided you would use a 1/2'' pex line. which is 1/2'' OD, the actual ID of 1/2'' pex 1s 3/8''

my recommendation. if you so wish to take it.

is to install MINIMUM 3/4'' meter to manifold.

then, 3/4 to each fixture.

others may differ, but i do not use 1/2'' pex, accept to hook up at the fixture

 

[Matt30]

For that same reason, I also usually run 3/4" as far as I can. If I have a long run that must be 1/2", I use the Q&E expansion fittings instead of crimp rings do deliver better volume