Hi all. I am replacing the drain, faucet, and handles in my old 1940's bath/shower combo. There is a small linen cabinet with an access panel right behind the bathtub. One plumber told me that he would need to rip out the wall inside the linen cab. in order the replace the old 3/4" shower riser, since new fixtures are 1/2". Another plumber told me that he will not need to replace the shower riser because there are converters for this type of situation. Does anyone know which is right, and what I should do? I have pics if that would help, just let me know. Any thoughts are much appreciated!

If you are going to be responsible for purchasing fixtures, I suggest that you purchase a consult with a plumber, or a designer who understands plumbing. It's a complicated subject, more so than the lay person realizes. Getting it wrong can cost you a lot in delays or callbacks. Your builder and plumber will not assume responsibility for that unless he controls the purchasing of the products.

Quote; "PVC is not allowed by code for hot water systems" WRONG! PVC is permitted for potable water supply but not allowed for potable water distribution period! (Supply is the direct buried lines from a well or municipal main to a structure--Distribution is all the piping inside the structure that moves potable water from the house main water shutoff to the point of demand). "I'd use PEX-b which has an NSF rating." Wrong again, All piping has both an NSF and an ASTM rating prior to being accepted by code. "Lasts longer and it is more sanitary." There is absolutely no evidence to indicate that PEX is any mor sanitary than CPVC or Copper. In fact quite the opposite is true. Don't believe it run a search for "Bio-film". Bio-film is an organic gelatinous mass that is known to cause legionaires disease and a number of other life threatening ailments. Bio-film forms in water that is standing static for prolonged periods of time, which is why the plumbing codes prohibit any capped lines longer than 12". Under laboratory test conditions Bio-film formed the quickest in Copper pipe, followed by PEX, then Polyethylene and finally CPVC. It seems that CPVC leaches a chemical that slightly retards the rate of bio-film formation whereas as copper ages it forms a layer of copper sulphate on the interior wall of the pipe. Copper sulphate is one of the best antibacterials known to man thus as copper ages it forms its own protection against biological growth. In fact, the antibacterial qualities of copper are so good that in the United Kingdom the are encouraging all hospitals and medical laboratories to replace their stainless steel lab tables with copper tables on the other hand, although you never hear it mentioned, both the ASTM Stadards and the manufacturers specifications state that all plastic piping systems should be sanitized at least once every 3 to 5 years. "Using a remote manifold system can save on piping." This is true, however their is nothing in the world that would prevent one from running Copper or CPVC in a manifold system if that is what they want. In fact, the manifold system is not new to PEX either, Polybutelene was run in in a manifold configuration the same as PEX is now, back in the late 70's & early 80's. Personally I find the manifold system to be total PITA. When I am working on a fixture in an upstairs bathroom I would much sooner just reach down and turn an angle stop off, instead of running down two flights of stairs and locating a manifold to shut the water off. (Perhaps this explains why any local codes now require the angle stops at all fixture locations whether they are fed by a manifold or not.) "PEX will expand when it freezes and will retain its shape when thawed,"- This is true, but generally a water line will freeze at a joint faster than on a run of the line and if PEX freezes at a joint the brass or copper fitting that makes the joint will fail in the exact same manner as copper would. Taking this to the next level, it is true that if the PEX pipe freezes it will expand and return to its shape when it thaws, but then figuring out how to thaw that line is a PITA. Basically you have three choices; 1, Use a low temperature electric heat gun (a hair dryer) to gently warm the pipe and hope you don't scorch the exterior of the pipe wall, 2. Repeatedly wrap the frozen section with rags soaked in hot water or 3. Disconnect the PEX at a joint then insert a smaller diameter tube into the PEX and pump hot water into the small tube while pushing it through the PEX until you reach the ice dam. There is also a major downside to the ability of PEX to tolerate freezing. Many plumbers have become so complacent with that fact that they give little to no regard about where they run the PEX in the first place.The last winter before I officially retired we spent more time on service calls thawing PEX lines than all other pipe combined, and in nearly every case we found the PEX run through joist bays in an unheated crawlspace or in an attic, but the homeowners told us they had been assured that if the PEX froze it wouldn't harm the pipe. For those of you who call yourselves plumbers, yet run the PEX wherever it suits you at the moment allow me to give you a bit of advice, when a homeowner has to pay a plumber $200 or $300 to come out and thaw a line, they really don't care if you had to install a new piece of pipe or not, its still an unexpected expense of $200 or $300 that they could have spent much more wisely. It has been stated the PEX requires less labor to install. Perhaps that is true and maybe its not. It is true that PEX requires far less "trained labor" than copper or CPVC. When running a PEX system you can stop at the corner and pick up a couple day laborers to help you because even a monkey could physically pull the pipe through drilled holes in the studding and drilling the holes is not rocket science either. Once the pipe is pulled one man should be able to move from location to location and make up all the joints. Now, for those of you who have a PEX system allow me to ask you this? Have you ever went down to your basement or to your utility space and stood there looking at your PEX pipe in admiration? If you answered yes, guess what, your PEX is not installed to code standard and perhaps that is why so many say it takes less labor. The labor savings was because they didn't properly run the pipe or finish the job.

Yes diameters need to be known. If you really want the showers to be balanced, you should use a manifold for both hot and cold lines and have a separate hot and cold line to each room.