Can PEX be installed the same way as copper?

[ckl111]

Hi,

I am getting conflicting information as to whether PEX can or should be run they same way copper pipes would.

This is for large 6-8,000 sq. ft. custom homes with 30-40 fixtures. One plumber has quoted to run PEX like copper, Teeing off 3/4" risers with 1/2" along the way.

Another plumber says this method may result in inadequate pressure since the I.D. of PEX pipe is much less than copper. The proper way to do it is a manifold system even though it will be more expensive. He also said that PEX is not rated for use with hot water recirculating systems and should not just be looped from the furthest line?

Any comments would be greatly appreciated.

 

[NHmaster]

An 8000 foot custom home with 40 fixtures and you want to cheap it out using PEX?

 

[Sponsor]

 

[ckl111]

An 8000 foot custom home with 40 fixtures and you want to cheap it out using PEX?

Actually, I don't. I have always used copper but a lot of builders are using it so I am investigating the "NEW" technology.

PEX is not simply marketed as being cheaper. It's supposed to better with scale build up, less chances of leaks because of fewer fitting, better flow, etc., etc. . I am sure it has its drawbacks too. One person told me a proper PEX system with all the manifolds and valves could cost even more than copper.

Honestly, I am quite hesitant to use PEX because even 25 year guarantees are worthless to me considering how long a house should stand.

How about this than, If it was a average size home, can PEX be run like copper pipes would?

 

[FloridaOrange]

You could, yes. The problem a lot of people have with PEX is that it is too new, it hasn't stood the test of time just yet. Just need a bad run of fittings, crimpers or tubing to cause you a whole mess of headaches down the road. As a designer I won't specify it, if a contractor wants to use PEX then he takes full responsibilty of that system. If copper is not a big deal as far as water quality is concerned I would sleep better at night with copper. By water quality, I mean that some areas (mine) have water that seems to eat copper over time. My house is plumbed with CPVC.

 

[Kingsotall]

cheap out with PEX

Don't tell that to every new house , lavish and "blow 'n go", build here for the last 10 years.

Ones that have recirc lines will be returned with PEX as well.

 

[Gary Slusser]

The advantage of PEX is in the manifold homerun system, not the branch and tee design of copper etc..

Branch and tee will barely save any time, and will reduce flow requiring larger diameters, more fittings, valving and supports.

PEX is rated for hot water, and so are manifolds.

The copper industry and plumbers wanting copper don't get into the many water quality problems that copper suffers from. But look at this 6-8000 ft house with a pinhole leak problem in copper, and then a joint leak here or there with a manifold PEX system. Which would you prefer if you had to suffer it.

 

[Redwood]

And the major disadvantage of the PEX homerun system is that recirculation is impossible so you wait & wait & wait for hot water at each fixture...

My Preference is a combination of trunk and branch with mini manifolds at the end use locations or nearby. Take a look at the link below. My Preference is on page 38...

http://www.toolbase.org/PDF/DesignGuides/pex_designguide.pdf

It will save about 1/2 mile of tubing that the hot water had to go through before it got to you....

 

[FloridaOrange]

And the major disadvantage of the PEX homerun system is that recirculation is impossible so you wait & wait & wait for hot water at each fixture...

My Preference is a combination of trunk and branch with mini manifolds at the end use locations or nearby.

That's exactly what I suggested to my brother when he was contemplating a recirc system somehow working with his maniblock system.

 

[99k]

I think trunk and branch looks much neater too ... not like a home run with spaghetti everywhere If you do copper, make sure you test your water to confirm/adjust it to be neutral so it won't eat the copper.

 

[ckl111]

And the major disadvantage of the PEX homerun system is that recirculation is impossible so you wait & wait & wait for hot water at each fixture...

My Preference is a combination of trunk and branch with mini manifolds at the end use locations or nearby. Take a look at the link below. My Preference is on page 38...

http://www.toolbase.org/PDF/DesignGuides/pex_designguide.pdf

It will save about 1/2 mile of tubing that the hot water had to go through before it got to you....

Thanks for the information. Truck and branch is pretty much the way copper is normally installed isn't it?

Problems with copper cause by water is not a problem as far as I know. Water is from a municipal source.

Wouldn't trunk and branch with mini manifolds be the remote Manifold system they talk about?

 

[Redwood]

Yes...
That's good...
Yes... on page 38 I believe..

 

[Gary Slusser]

I don't like and would never have a hot water recirc system.

Low pH acidic water is only one of many causes of pinholes in copper tubing and many 'city' water customers have pinhole leak problems. Washington DC is famous for their ongoing problems.

I think the mention of miles and a half mile of tubing are exaggerations.

 

[Redwood]

I don't like and would never have a hot water recirc system.

I think the mention of miles and a half mile of tubing are exaggerations.

If you like running the hot water and waiting for it go right ahead...
Many people are seeing the Green in conserving water.

I have seen installed systems in homes where the tubing saved could be sumed up in those units of measurement.

We call them McMasions!

 

[FloridaOrange]

I don't like and would never have a hot water recirc system.

Why not? Have you had a bad experience with one?

I think the mention of miles and a half mile of tubing are exaggerations.

Not in some of the places I design. That McMansion above is pidly compared to some clubhouses and private homes down in Naples.

 

[Gary Slusser]

Hot water recirc systems can cause water quality problems and corrosion and they increase the cost of heating water and installation costs to put them in.

IMO a much better solution for the go go speedy McMansion type people is another and possibly smaller water heater close to the point of use. And I'd turn it off until guests showed up. But that's frugal 'slow down you'll live longer' me. And the fuel and other energy costs to heat water and pump it around a building 24/7 to save a couple gallons and minutes of wait time are more expensive than the cost of the water, at least for now and into the future some.

 

[Jadnashua]

Hot water recirc systems can cause water quality problems and corrosion and they increase the cost of heating water and installation costs to put them in.

Someone did a study I read that confirmed that, but said the break-even point was about 4-hours of recirculation...if you had a system on a timer or a motion sensor, or something that would allow the system to only run when needed (most of the time), then it was actually cheaper to run recirculation than not.

 

[Redwood]

Someone did a study I read that confirmed that, but said the break-even point was about 4-hours of recirculation...if you had a system on a timer or a motion sensor, or something that would allow the system to only run when needed (most of the time), then it was actually cheaper to run recirculation than not.

Yup!
I've seen that same study...

Besides that PEX corrodes real bad...

 

[Gary Slusser]

The test also shows that more than 4 hours and it costs more to recirc than not.

Not that it doesn't exist but other than you now, I've never heard or seen any info concerning erosion corrosion in any plastic potable water line material. Unlike copper, where too much silica in the water or velocities at/over 8ft/sec cause it to fail.