Plumbing Question: Copper or Pex for main run
 

I'm moving my water heater into to the attic. Just bought a tankless and this will free up a whole 5x5 closet that I will make into a pantry.

I ran 3/4" copper pipe up the wall from under the house to the attic and will terminate at the water heater.

For under the house (crawl space), would it be best to run 3/4 copper for the length of the house and then convert to PEX via a multi-port manifold or run pex the whole way?

I previously ran a pex line when I built a new laundry room but I seem to hear the pipe flex and knock from time to time. My thought is to run a long copper pipe and then branch out using pex.

Just wondering what the experts would do, I have very little plumbing experience. It's not required that I do anything but tap into the existing plumbing but with my house being almost 70 years old, I'm tasting rust in the water and want to slowly replace all the pipes.

Pvc?

Pex is fine but I wouldn't put it in my house nor my client's. I just don't like the thought of water running through plastic. Plastic is made of chemicals. In some of the hotter climates, when the water is first turned on in the shower, that water smells like plastic.

Personally, I do 1 "copper as the main line. Is the main on the street 1"? How bifg is the house?

Copper.
Rats like to gnaw on PEX.
I find copper just as easy to work with as PEX. So the only real advantage to PEX is price point - which tends to take a back seat when my house is concerned.

Oh yeah, forgotten to mention the rats issue.

I'm not real fond of Pex yet, but I hate copper. I have leaks (OK A leak so far) due to corrosion of the copper pipe. I would run PVC for as much of the piping as I could, and use PEX for the rest. No more copper in my life.

Mr Wdfifteen, one of the main reason they leak is at the joint where the stupid plumber use flux to cool the joint and did not wipe of the excess flux. It is not the copper, its human error also known as goddamnlazy bastards

The main line coming into the house is 1" so I guess I should use 1" copper until I convert down to specific areas. I used 3/4" copper up the wall to the attic because the tankless heater uses 3/4" but I have not yet connected anything under the house.

This is a project that's going to take a little time because I hate crawling under the house. However, straight copper (at least from one end to the other will be much easier to handle).

CPVC for potable water, not pvc. I've seen copper corrode & get pinhole leaks, as soon as 1 year after installation, especially with well water.

I don't know what kind of mice problems you guys have in other parts of the country, but jeez, use pex and get a cat!

We switched over to CPVC and/or Pex depending on the job, over 10 years ago, no problems.

Make sure you take come soapy water filled spray bottle and a rag to clean out the joints when its still hot. If not, the flux will eat through in 5 years.

This is what I have always done for people. Run a 1" line and bypass the regulator to a back spigot so you can really blast the birds from the neighbor's roof. Great for cleaning instead of spitting water out of the hose. Run another 1" near the end so branch lines can be run off it. I usually run 3/4" branch line and narrow it down for the faucets in the kitchen and faucet for the bathroom sink. 3/4" straight to the shower valve. Many valves accept 3/4" now. I know, I know, only 1.6 fpm goes through. So 1/2" is really enough but I don't like it because i have to narrow it down only to have to open it up for 3/4" again.

Cpvc is only allowed under special circumstances in LA, maybe the state?

Ditto on most of this. With well water, many people in this area develop pin holes in copper - inside walls and ceilings, argh. CPVC in my place has held up perfectly for 39 years now, although I've got some new branches in PEX. I have a cat.

The union plumbers that taught me say only copper unless you truly are forced to use Pex. There are some places where putting copper is pretty tough, and some types of faucets and stuff are Pex or Pex-compatible only (Grohe high end fixtures have 1/2 npt but do not allow any heat for about a mile away....sort of awkward to use copper in that case).

Do the job right, clean, flux, solder, clean...no issues unless you have something like HW recirculation and get erosion.

Dennis

There is no perfect piping. It depends a great deal on your makeup water and whether it tends to be hard, soft, or corrosive. Corrosive well water is a big problem for copper so if you use it you need to get the saturation index up so it is slightly scale-forming and test your water often. This will coat the inside of copper piping and guard against leaks.

CPVC is a pretty good choice if it is legal to use in your area for potable water. Durable, easy to work with, completely resistant to corrosive water.

Pex is cheese flavored and rodents just love the stuff. Tract home builders use it because it is fast and cheap but rodent protection is a must.

Copper generally works great in SoCal and AZ because our water tends to be scale forming offering a lot of protection. It's not cheap but very durable. I choose this here but would hesitate in the NE states or on a well due to potential corrosion.

Regarding problems with rats...........you don't always have to get a cat.

Did you know that Queensland Heelers are part Rat Terrier?

Kill two birds with one stone - rescue a Heeler (or 10) from your local shelter and maintain a rat free zone on your property! :)

https://scontent.ftpa1-1.fna.fbcdn.n...62&oe=56B66208

The house I bought had a lot of CPVC in it and I've been slowly upgrading to copper. The CPVC hasn't given me any problems, although the stuff I have replaced was extremely brittle, which makes me a tad nervous- will be happy once it's all gone. I use the middle grade of copper "L" to make me feel better.

Not the case in my situation. My horizontal run 3/4 copper pipe corroded through at least 12" from any joint. I was shocked to learn that the expected life of modern copper has gone from a projected 50+ years to only 20-25 years. My house is 22 years old and the copper has corroded through.

We generally don't have problems with copper in my area and is very commonly used (until the advent of Pex). My 70 year old house has galvanized pipes that are starting to produce rusty tasting water in bathrooms that are not used very often.

I don't have a problem using copper and since it's my house and I will be here for a long time, I want to do what's right. Since I'm not a plumber, it will be a long term project but room-at-a-time is ok with me. I'm just going to start with the foundation (i.e., main lines for hot/cold and water heater). In the process, I will setup for branching out to rooms.

As far as mice & rats.....I have two cats and several in the neighborhood - I don't ever have mice or rats, ever.

I would never use plastic pipe for anything under pressure inside a house. Regular Type M copper pipe lasts for ever in the southwest but if you live somewhere that you worry about copper corroding, use Type L or Type k.

Is Pex holding up in your region or are there similar life expectancies for Pex as you are seeing for copper?

Dennis