Oversizing PEX runs

[boober]

I am replacing the entire plumbing system of my house. I currently have 50 year old galvanized system, that is rusting through and has exceptionally poor pressure. I recently bought all copper piping(M) in 3/4 and 1/2 sizing (prior to its astronomical price jump) but am having second thoughts about using it. I am considering using PEX as a more simplified solution. Having read some concerns about PEX and decreased flow do to fittings, what would be the concensus on using the next step up for each pipe- ie using 1" in place of 3/4", 3/4" instead of 1/2", etc...? I am leaning toward the Wispro expander tool for the connections. Any opinions on this (and or the Wisbro expanding tool itself...)?
Also, there was concern noted about biofilm developing, has anyone had experience with that?

Any help is most appreciated.

 

[Jimbo]

Because PEX sizes are called out at OD and copper as ID, then in general you need the next size up from the copper size to get the same GPM.

 

[Sponsor]

 

[Master Plumber Mark]

wirsbo pex....

actually you can run pex to each fixture from a main mainfold
if you so wish.... the run can be 1/2 inch to each fixture
from a main 3/4 or 1 inch mainfold and it would all work fine

its not a big problem..... the stuff is so cheap companred to copper
if you are worried about it , just run some 3./4 manifolds to
different bathrooms then kick it down from there...


with wirsbo pex just about anything will work out....

 

[boober]

actually you can run pex to each fixture from a main mainfold
if you so wish.... the run can be 1/2 inch to each fixture
from a main 3/4 or 1 inch mainfold and it would all work fine

its not a big problem..... the stuff is so cheap companred to copper
if you are worried about it , just run some 3./4 manifolds to
different bathrooms then kick it down from there...


with wirsbo pex just about anything will work out....

Almost all of my plumbing is in a small area. The bathroom abutts the kitchen, and the basement bath I plan to add will be directly below the 1st level bath. So I planned on running one long main to a manifold, then branching off, so the amount of PEX isn't really an issue. I just want to make sure my water pressure is increased. I'm sick of flushing and having to wait to wash my hands... (not quite, but almost...)

I'm also a bit concerned about the biofilm.... But I'd assume flushing thie system would be relatively easy. It would be a pain if it was a yearly necessity though... Anyone know if chlorine in municiple water helps to reduce the biofilm?

 

[boober]

Because PEX sizes are called out at OD and copper as ID, then in general you need the next size up from the copper size to get the same GPM.

Ahhh.... Thanks. So when people talk about PEX sizes, do they normally refer to the OD size, or the ID size? And thanks for the quick responses ...

 

[hj]

Pex

They refer to the "inside size" but are using the copper tubing size. PEX o.d. is the same size as copper, but since the wall is thicker the opening is smaller. If you remember your geometry, a small reduction in the size of a circle creates a large change in its area, and area is what you are concerned with when it comes to the opening in a pipe.

 

[boober]

They refer to the "inside size" but are using the copper tubing size. PEX o.d. is the same size as copper, but since the wall is thicker the opening is smaller. If you remember your geometry, a small reduction in the size of a circle creates a large change in its area, and area is what you are concerned with when it comes to the opening in a pipe.

That makes sense and adds another dimension to the issue. Not only is the ID smaller, but the fittings reduce even more so. I guess my question then is, would a 1" PEX give the same flow ratre as a 3/4" copper? Or would it need to be even larger?

 

[Geniescience]

One size up is sufficient to MORE than compensate.

when you go one size up, you are theoretically doubling the flow capacity. That is approximate. Nonetheless, a pipe's wall thickness doesn't eat up that much space as to make that much difference. My mathematically calculated opinion.

The concept of running a whole new line to the faucet and to the toilet, separately, is a good one. It'll help, if pressure is low.

If you bend Pex so as to reduce the number of elbows, you gain flow too. Compared to copper which needs elbows.

How big is your entrance? The water coming in to the house. How much pressure, how big a pipe?

DAvid

 

[boober]

when you go one size up, you are theoretically doubling the flow capacity. That is approximate. Nonetheless, a pipe's wall thickness doesn't eat up that much space as to make that much difference. My mathematically calculated opinion.

The concept of running a whole new line to the faucet and to the toilet, separately, is a good one. It'll help, if pressure is low.

If you bend Pex so as to reduce the number of elbows, you gain flow too. Compared to copper which needs elbows.

How big is your entrance? The water coming in to the house. How much pressure, how big a pipe?

DAvid

Not sure on the pressure, but it's a 1" pipe coming into the house. It is then reduced to 3/4". Although I believe any pipe would be an improvement, I want make sure I size it appropriately. I plan on making sure that bends are kept to a minimum.
I am now looking at tools for PEX. Specifically the Rehau system. I like the idea of the clamp over the fitting. It's probably overkill, but I lean towards that more than the Wisbro system. Either I believe will be better in terms of not reducing flow any more than necessary. Anyone have any opinions on either system?

 

[Geniescience]

boober

Do you currently have 3/4" pipe everywhere? Or does it get reduced to 1/2" for each fixture?

Have youe seen the kitec Aqua system? Their pipe is huge inside.

 

[Master Plumber Mark]

please explain "bio-film"

What in the hell is the "bio --film" that you are so worried about

and who or where did you read that you must flush it out of the

system every year or so???

Did some fireman tell you a tall tale??


the chloriine in the water systems kills everything
so that we can drink it without getting sick.

thats a new one on me.


please explain what you are talking about

thank you

 

[Geniescience]

yeah Mark. Have we all seen the crud and slime that gets deposited on the inside of copper pipe walls? Makes me sick already just to think that I was drinking through those pipes for years.

Boober, if you really want high flow, check out the advantages of Kitec Aqua. The pipes bends even tighter than Pex. I used it to bring tons of water to my tub and shower. That is where i wanted maximum flow.

david

 

[boober]

boober

Do you currently have 3/4" pipe everywhere? Or does it get reduced to 1/2" for each fixture?

Have youe seen the kitec Aqua system? Their pipe is huge inside.

Yeah, it reduces to 1/2" at all fixtures, except the hot water tank. I thought I'd run the next size up to each fixture then install the proper copper size for the connection.
I've heard both that pressure is increased (from the lack of elbows) and decreased (due to ID size), so I don't know what to believe. I figure I'm pretty safe with an oversized run.



As for the biofilm, here's a study on biofilm based on material and an article on it... although the article mentions copper as the highest, according to other info I read, it had lower levels due to an anti-microbial properties Cu exhibits.
Chlorine doesn't kill as much as you think. Those of use in the Metro Milwaukee area experienced that a few years back with the Chrypto outbreak. It ended up killing my dog actually (older dog that had kidney failure due to the crypto...)

 

[boober]

yeah Mark. Have we all seen the crud and slime that gets deposited on the inside of copper pipe walls? Makes me sick already just to think that I was drinking through those pipes for years.

Boober, if you really want high flow, check out the advantages of Kitec Aqua. The pipes bends even tighter than Pex. I used it to bring tons of water to my tub and shower. That is where i wanted maximum flow.

david

I've looked at that, but is it cost effective if I don't have many 90 degree bends? Would I need different tools than for normal PEX?

I am considering buying all 1" at this point and running that to the copper "connectors", because the amount of pipe I need of each size is much less than the 100 feet per roll that seems to be the smallest amount I can buy. All my plumbing is in on part of the house so the runs would be quite short, except from the main to the homerun which would be maybe 50' total... Any thoughts on that?

 

[Lakee911]

Chlorine doesn't kill as much as you think. Those of use in the Metro Milwaukee area experienced that a few years back with the Chrypto outbreak. It ended up killing my dog actually (older dog that had kidney failure due to the crypto...)

I didn't read the article, but I'll chime in. Chlorine, and other disinfection methods, can create Disinfection By-Products (DBPs). Some of these DPBs are harmful, but in general, chlorinated water is one of our biggest advances in health technology, in my opinion. Other options exist for disinfection besides the Chlorine Gas. Some better, some worse.

Sorry to hear about your dog.

Jason

 

[Geniescience]

Any 3/4" will be HUGE compared to your 1/2" copper currently in use

the kitec product doesn't need a crimping tool.

But never mind. You are well on your way to getting what you want with ANY 3/4" pipe. Forget the false ID and OD dilemma. You have had that explained to you before, above.

Proceed with your plan. Install 3/4" pipe.

David

 

[Bob NH]

PEX v. Copper

PEX OD is the same as corresponding copper pipe. PEX is produced with a wall thickness that is 1/9 of the OD. That results in the following relative areas:

The flow area of 1/2, 3/4, and 1" PEX is 73, 70, and 69 percent respectively of the corresponding Type M copper pipes.

The flow area of the "PEX next size up": 3/4 PEX v. 1/2 Copper is 143%, and 1" PEX v. 3/4" copper is 116%.

Comparing CPVC in Copper Tube Sizes, the areas are 81, 78, and 76% of copper, and the "Next size up" areas are 158% for 3/4 CPVC v. 1/2 Copper and 129% for 1" CPVC v. 3/4 copper.

CPVC is also available in Iron Pipe sizes but I have never seen that in HD. It could be used size-for-size to replace galvanized pipe.

The only difference that I have been able to find with the Kitec brand PEX suggested by Geniescience is that the Kitec is 2 to 3 times as expensive as the Wirsbo.

CONCLUSION:
If your flow is adequate and controlled by the fixture, such as toilets, lavatories, and most household kitchens, you can stay with the same size and not see any difference.

If you have high flow, such as main distribution pipes, showers, clothes washers, shop sinks, outdoor faucets and similar applications, upsizing one size will improve your flow.

 

[Geniescience]

Fantastic, Bob!

Good numbers.

The pex-al-pex layered pipe made by Kitec, a German company, is sold as either Kitec (orange) or Aqua (blue). Maybe someone will go find their site and report back. Its sizing is huge. It was not based on the pre-existing copper or iron pipe sizes we have here, unlike Pex or CPVC.

 

[Master Plumber Mark]

frogs in well water....

well, I did not know that city water was so unhealthy....

I have seen some deposits in copper pipes , but never took notice

of it..... and I dont think I am gonna lose any sleep over it.....

----------------------------------------------------------------------
NOW, if you really want to hurl chunks, Well water can really be


a nasty swill that people drink every day.......

biological iron ect slimeing up the pipes......pbbs,

all sorts of fun stuff..... septic tank water leaching into

the neighbors well ect.....



one time I actually chased frogs out of the top of a

well head. and I think that their was a family of them down in the

bottom of the well too...



anyway, their are levels of filthy water that make city water look

perfectly tame, and on average not many have died from it

 

[Cass]

Bob NH I think the flow % should be based on the ID size of the fittings as it is smaller than the pipe. I have searched online but could not find the PEX fitting ID sizes anywhere.