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Professional Bullshioter
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Discussion Starter #1
I don't use the stuff but, this puzzles me. Who would want to lose all that wall space of the mounted manifolds and associated spaghetti?

How does one run a whole house on a 3/4" pex line when the effective opening of the fittings is closer to 1/2" if I was guessing?

In my particular state I believe a tub/shower valve would require a 3/4" line to it due to fitting restriction.

I understand why you guys use it, and I'm sure it prolly gives the water a better taste but, I just don't care for it.

I don't see why you need all those valves when you have stops as well as main valves at each bathroom group. Or worse case, shut the whole house down.
 

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Pex doesn't have to be run as a manifold system. We run pex just like you would run copper. I don't know about your flow restriction point. Obviously it's true but we haven't had and problems as of yet.
 

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Master Plumber
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A restriction at a single point is not as big of an issue as we tend to think it is. In other words, a 100' long 3/4" pipe that has 4 restrictions to 1/2" will still carry much more column than a 100' long 1/2" pipe.
 

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The manifold can be put somewhere that it isn't in the way. I'm old-fashioned - in my house it's in the utility room next to the water heater and sump, along with a floor drain.

Mine's been in for quite a while, and it's polybutylene. I don't have pressure-balancing faucets and it's virtually impossible to get scalded or frozen when water is used somewhere else - you never even notice.

Almost two years ago, I did a bathroom remodel. I removed the tub since I didn't really need one on that floor and put a storage closet in its place. Easy enough to do: I just turned off the valves and cut off the pipes.

Here, we don't normally have valves on tubs and showers, so, with the manifold you can shut them off to work on them without disturbing the rest of the system.

I've done repairs a couple of times on a house where the lime sediment from the water heater backs up into the water lines. I can shut off the toilet line that always gets affected, open up the end of it under the toilet and put a piece over into a bucket, then turn the valve on and off to flush the line. It's happened a couple of times and the HO won't spend the money for an expansion tank on the WH, or even a check valve.

Those are just some of the reasons a manifold might be handy. Some houses have such a big basement that the space taken by the manifold doesn't amount to a hill of beans.
 

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The ports that pass through the valves can be 3/8 or smaller, the fitting for pex pipe does not effects the flow at all.
 

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My worry would not be restriction of flow, it would be putting a fitting in a position where it is vulnerable to the most corrosive thing on Earth, water in motion. I've seen copper water lines that were not reamed get eaten away inside the fitting from this, what is stopping the same thing from happening to PEX fittings?
 

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KTS next time to see this, post a picture, I myself have never seen this reaction, never really looked for it, keep in mind the brass pex fittings are thicker then your type L copper, and there brass, if that makes any difference at all. Guess time will tell, If i'm still around to know the truth, and not 6' under when the truth is revieled.
 

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The manifold can be put somewhere that it isn't in the way. I'm old-fashioned - in my house it's in the utility room next to the water heater and sump, along with a floor drain.
Nuttin' like a good old fashioned PEX installation...:laughing::laughing:


Sorry, couldn't resist.
 

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KTS next time to see this, post a picture, I myself have never seen this reaction, never really looked for it, keep in mind the brass pex fittings are thicker then your type L copper, and there brass, if that makes any difference at all. Guess time will tell, If i'm still around to know the truth, and not 6' under when the truth is revieled.
It's called impingement if you want to try doing a search for it.

There are many grades of brass and brass alloys, some of them are no better in durability than zinc. Please keep in mind, I have never seen or held a PEX fitting, so I am not passing any judgment on the quality of the fittings, merely pointing out that whenever you put a restriction on flowing water it starts to tumble, and eat away at the point of restriction from the tumbling action. Picture the Grand Canyon, it was formed in this very way.
 

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Turbulence in the pipe, is this what your talking about, don't you think even if one fails to ream the pipe, that to produce a smooth bore that the rough edge that the water flows across will wear it down at the point only, or take a smooth bore pipe, reamed, is there still turbulence at the 90 and tees as water flows around them? Not saying this is not a factor in failure of a fitting, but of all the years I've made repairs on copper pipe, I have not seen any pinhole leaks in a fitting, yes in the pipe before or after a fitting, but not a fitting, when I find a fitting leak, it's cause of a bad solder joint. I wish I had a testing facility to take pipe and fitting to run a constant flow of water 50psi to 60psi through them give or take billions of gallons of water to see a failure take place.
 

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Turbulence in the pipe, is this what your talking about, don't you think even if one fails to ream the pipe, that to produce a smooth bore that the rough edge that the water flows across will wear it down at the point only, or take a smooth bore pipe, reamed, is there still turbulence at the 90 and tees as water flows around them? Not saying this is not a factor in failure of a fitting, but of all the years I've made repairs on copper pipe, I have not seen any pinhole leaks in a fitting, yes in the pipe before or after a fitting, but not a fitting, when I find a fitting leak, it's cause of a bad solder joint. I wish I had a testing facility to take pipe and fitting to run a constant flow of water 50psi to 60psi through them give or take billions of gallons of water to see a failure take place.
I have unsweat joints and the fitting is fine, the top of the pipe is gone, in a v shaped pattern.
 

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Professional Bullshioter
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Discussion Starter #12
I have replaced 2" copper 90's that were between a boiler and holding tank. The circ pump was oversized. They were wore out on the ouside of the radius as well as thinning of the pipe on the 90 outlet.

I find it hard to believe a restrictive fitting will not affect flow. I would like to see a gpm test to prove this. Our code requires gross oversizing due to this restriction.

The pex fittings I have used on hydronics are compression.

You guys ever have issues with punctures of the exposed pex due to dog chewing or kids messing around? I don't know just how tough this stuff is.

Killer,
speaking to the point you made. I agree. I wonder why not stainless fittings?
 

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By the time the water flow hits any valve in the system, angle stops, faucets, there is so many sharp, rough edge corners water need to flow across/over, if there was a problem to show these would have proven prove bass will not hold up, we would know it by know. IMO I don't see problems.
 

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I find it hard to believe a restrictive fitting will not affect flow. I would like to see a gpm test to prove this. Our code requires gross oversizing due to this restriction.
And that is based on piping systems designed to have zero restrictions when properly installed, PEX is a system that has a restriction at every joint. I have to wonder how much actual installation testing was done on this stuff before allowing it to be sold.
 

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When I install pex, I try when ever possible to run the line in the wall with no joints. I try to put expansion joints in where ever possible. Pex and copper are not the same and should be run diiferently imo. You can run it the same but as previously said, you have a potential for leaks and volume drop by doing so. This is where the manifold system really shines, less joints behind enclosed walls.

Pex is popular in my area for a different reason, copper theft. It's just a diifernt system to install and should be treated as such.
 

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Pex is popular in my area for a different reason, copper theft. It's just a diifernt system to install and should be treated as such.
I'm gonna quit this thread, the stuff isn't even legal here so I have no real business commenting on it. When we need an alternative to copper we use galvanized.
 

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Grumpyplumber said:
Nuttin' like a good old fashioned PEX installation
Like I said, it's polybutylene - and that's ancient! :laughing:

When I started plumbing houses, I tried to bring the main water line up in a utility room, where you might also find the water heater, a floor drain, and perhaps a furnace. Keeping it all in a serviceable area seemed like a good idea. I hate crawling under a set of stairs in a split entry to get at the main valve or moving beds and stored stuff out of the way to get to one in the wall or a closet.

So, it just seems natural to me to put the PEX manifold in there, too. Want to drain the system to close the house down for winter? Why have the manifold across the house in a hallway?
 

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I'm gonna quit this thread, the stuff isn't even legal here so I have no real business commenting on it. When we need an alternative to copper we use galvanized.
Aw come on, be a sport & stick around...next topic: "Approved garden hose applications for residential water mains"
 

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Like I said, it's polybutylene - and that's ancient! :laughing:

When I started plumbing houses, I tried to bring the main water line up in a utility room, where you might also find the water heater, a floor drain, and perhaps a furnace. Keeping it all in a serviceable area seemed like a good idea. I hate crawling under a set of stairs in a split entry to get at the main valve or moving beds and stored stuff out of the way to get to one in the wall or a closet.

So, it just seems natural to me to put the PEX manifold in there, too. Want to drain the system to close the house down for winter? Why have the manifold across the house in a hallway?
I fully agree...just hadda make a jab over the "old fashioned PEX":laughing:
 

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There is only one thing I can say about pex, it's flie's on.gif . It has it's uses, but not for new installs and repipe's. It just make's me laugh when I do see them. Smile laughing.gif Where is the plumbing trade going when people put in pipe that Stevie Wonder can install. I'll tell you it's going down the Smile being flushed.gif
 
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