Author Topic: Copper to Pex  (Read 1916 times)

Roboturner

  • Bristles
  • ***
  • Posts: 442
  • Age: 29
  • Location: Colo-RAD-o
  • No Snacks, Just Math
Copper to Pex
« on: August 10, 2017, 04:16:30 PM »
I'm going to swap out some copper pipes in our basement with Pex (the copper pipes are in the way and some connections are corroding). It will be a few short runs, keeping the existing copper in the walls and to the fixtures.

I understand that the nominal ID of pex is smaller than copper, so I have seen some folks suggest up-sizing when moving from copper to pex to maintain flowrate. My question is for short (<50' 10' runs) will it be necessary to up-size? i havent seen a lot of 1/2" copper to 3/4" Pex adapters. Also are there any tips or tricks to keep in mind? I know part of the appeal of pex is to do home-runs to a central manifold, but this project will be more geared towards replacing short runs of copper to get them out of the way.
« Last Edit: August 11, 2017, 08:17:35 AM by Roboturner »
"I win again, just like always!"




ixtap

  • Bristles
  • ***
  • Posts: 427
Re: Copper to Pex
« Reply #1 on: August 10, 2017, 04:34:16 PM »
Have you looked online? For our boat projects, we order all of our connectors online because our preferred brand is not available locally.

I am not sure that 50' is actually considered a short run, but it is more important to be aware of how many connections are coming off of each run. ie Are you making a run to the upstairs bathroom wherein the shower, sink and toilet will all be fed by it?


Papa bear

  • Pencil Stache
  • ****
  • Posts: 519
  • Location: Ohio
Re: Copper to Pex
« Reply #2 on: August 10, 2017, 04:45:31 PM »
I have never heard of sizing up for pex and I've done a few houses, some new, some copper to pex retrofit.  I have never noticed any reduction in water flow. 

If I have access to the coupling, I usually use a push fitting. But if you are burying it, you need to solder on one of the brass barbs that the pex will crimp on to.

Good luck!


Sent from my iPhone using Tapatalk

paddedhat

  • Handlebar Stache
  • *****
  • Posts: 2053
Re: Copper to Pex
« Reply #3 on: August 11, 2017, 05:58:25 AM »
I plumbed a couple of dozen new homes with it. I ran 3/4" as trunk lines, then teed off with 1/2" to all fixtures. Never had an issue with pressure or volume. In reality, all modern fixtures are made to limit flow, so there really is no need provide excess volume to the fixture, since it won't be used anyway. If you haven't bought any tools or fittings yet, take a look at the stainless steel band clamps and pliers. Far superior to the compression band style and it needs one inexpensive tool to do all sizes of pipe.

Skills Barterer

  • 5 O'Clock Shadow
  • *
  • Posts: 21
Re: Copper to Pex
« Reply #4 on: August 11, 2017, 06:12:20 AM »
I would also make sure to measure the outer diameters of the copper, and the inner diameters of your planned adapting fittings before splicing to make sure they will fit.  If it is really old copper you may have some fitment issues. 

Roboturner

  • Bristles
  • ***
  • Posts: 442
  • Age: 29
  • Location: Colo-RAD-o
  • No Snacks, Just Math
Re: Copper to Pex
« Reply #5 on: August 11, 2017, 08:14:24 AM »
I am not sure that 50' is actually considered a short run, but it is more important to be aware of how many connections are coming off of each run. ie Are you making a run to the upstairs bathroom wherein the shower, sink and toilet will all be fed by it?

to be honest their more like 10'

yes one upstairs bathroom split and one downstairs bathroom split
"I win again, just like always!"




Roboturner

  • Bristles
  • ***
  • Posts: 442
  • Age: 29
  • Location: Colo-RAD-o
  • No Snacks, Just Math
Re: Copper to Pex
« Reply #6 on: August 11, 2017, 08:16:46 AM »
I plumbed a couple of dozen new homes with it. I ran 3/4" as trunk lines, then teed off with 1/2" to all fixtures. Never had an issue with pressure or volume. In reality, all modern fixtures are made to limit flow, so there really is no need provide excess volume to the fixture, since it won't be used anyway. If you haven't bought any tools or fittings yet, take a look at the stainless steel band clamps and pliers. Far superior to the compression band style and it needs one inexpensive tool to do all sizes of pipe.

perfect, and yes i read similar suggestions on SS crimps vs copper compression rings, so that was my thought
"I win again, just like always!"




BudgetSlasher

  • Bristles
  • ***
  • Posts: 333
Re: Copper to Pex
« Reply #7 on: August 12, 2017, 08:25:26 AM »
I've used PEX to augment and relocate runs in a copper trunk and branch system (the flexibility of PEX is a real lifesaver when threading up an existing wall). I've always used 1/2 for the run to fixtures and I have never had a complaint on the water pressure.

PEX has a smaller ID than copper, but the explanation I have heard goes like this; due to the flexibility of PEX you can make 90 degree turns using an external guide with a larger radius than a copper 90 degree elbow, which in turn reduces resistance. So, basically minimize the fittings you use and you should be ok.

Radagast

  • Pencil Stache
  • ****
  • Posts: 637
  • Location: West of the Mountains, East of the Sea
Re: Copper to Pex
« Reply #8 on: August 20, 2017, 03:37:16 PM »
Stopping by late to say: No. The same nominal size PEX should make an insignificant flow/pressure difference vs. copper. PEX should be a little smoother/ have less resistance inside and will not require as many sharp bends. Plus, 10 ft is a very short distance, especially considering the low flow rates of household fixtures.

Roboturner

  • Bristles
  • ***
  • Posts: 442
  • Age: 29
  • Location: Colo-RAD-o
  • No Snacks, Just Math
Re: Copper to Pex
« Reply #9 on: August 21, 2017, 03:38:25 PM »
Thanks all, you've satiated my concerns
"I win again, just like always!"




ncornilsen

  • Pencil Stache
  • ****
  • Posts: 627
Re: Copper to Pex
« Reply #10 on: August 22, 2017, 08:01:12 AM »
Thanks all, you've satiated my concerns

If you have any concerns at all about rats getting near your pex, reconsider.

I had a rat get in my garage and at holes in the pieces of unused PEX I had slated to be installed... they like it for some reason.

Roboturner

  • Bristles
  • ***
  • Posts: 442
  • Age: 29
  • Location: Colo-RAD-o
  • No Snacks, Just Math
Re: Copper to Pex
« Reply #11 on: August 22, 2017, 11:33:29 AM »
Thanks, its along the rafters so shouldn't be an issue (and we dont have rats thank god)
"I win again, just like always!"




Spork

  • Walrus Stache
  • *******
  • Posts: 5759
    • Spork In The Eye
Re: Copper to Pex
« Reply #12 on: August 23, 2017, 10:20:44 AM »
So, yeah, rats are a real concern with pex.

My uncle had to replumb his entire house due to rat damage.  This includes tearing out sections of drywall to get to the pex in the wall.  They literally chewed every single segment of his plumbing.

This shouldn't stop you from using pex, but it should make you go nuclear really fast if you ever hear skittering in the attic.  And yes, rats are very easy to get and can be very hard to get rid of.  We had a neighbor that was a food hoarder.  There was a hail storm and she had her roof replaced.  Following that, every house for a block each direction had rat problems.  I trapped or killed over 30 in my house in about 3 months time.
Some will sell their dreams for small desires
Or lose the race to rats
Get caught in ticking traps
And start to dream of somewhere
To relax their restless flight

Wanderer10

  • 5 O'Clock Shadow
  • *
  • Posts: 5
  • Age: 30
  • Location: Buffalo
Re: Copper to Pex
« Reply #13 on: August 28, 2017, 09:07:35 PM »
Wow. Rats eating your Pex. That is one of the worst things I have ever heard!

BTW I know plumbers who do upsize pex because of the smaller interior diameter. They use 1'' for the runs and t off with 3/4. Unless you have really low water pressure, this seems unnecessary to me. They do it just in case. I redid my whole house with 3/4 runs and 1/2 at the fixtures and it's fine.

paddedhat

  • Handlebar Stache
  • *****
  • Posts: 2053
Re: Copper to Pex
« Reply #14 on: August 29, 2017, 05:18:58 AM »
Wow. Rats eating your Pex. That is one of the worst things I have ever heard!

BTW I know plumbers who do upsize pex because of the smaller interior diameter. They use 1'' for the runs and t off with 3/4. Unless you have really low water pressure, this seems unnecessary to me. They do it just in case. I redid my whole house with 3/4 runs and 1/2 at the fixtures and it's fine.

I had a customer who demanded 1" on a new house, and even paid for a loop system of 1"  that didn't have a dead end, but was essentially a ring of pipe on each floor that the fixtures were tapped into. This was all supposedly to keep pressure and flow up. The house was new, and on a private well. Given the comparatively low pressure and volume available on a small rural well, and the limitations imposed by modern low flow fixtures,  IMHO, it was a waste of pipe and money. I did dozens of new rural homes in 3/4 and 1/2 PEX and only heard a complaint once regarding garden hose flow. I tested the flow rate and volume against the well specs. and the 1/2" line delivered all the well was capable of producing. Turns out the customer was used to washing his car in the city, where he needed a regulator on his incoming water line to keep the municipal pressure from blowing his plumbing system apart. His rural well was only producing 1/3rd of that pressure.

BudgetSlasher

  • Bristles
  • ***
  • Posts: 333
Re: Copper to Pex
« Reply #15 on: August 29, 2017, 06:17:39 PM »
Thanks all, you've satiated my concerns

If you have any concerns at all about rats getting near your pex, reconsider.

I had a rat get in my garage and at holes in the pieces of unused PEX I had slated to be installed... they like it for some reason.

Great, I just ran pex earlier in the week to relocate the kitchen sink . . . I was drilling blind behind the drywall (between the studs) and when I finished there was a dead mouse impaled on the drill bit . . . and six more quickly relocated into the shop-vac.

I guess I should leave a generous portion of rodicide in the stud bay before I close it back up.