Pex tubing retrofit for DIY project?

[Todd T]

The plumbing system in our 1920's era home has lots of problems. I'm seriously considering replumbing the entire 1850 square foot home with pex using Vanguard's Manobloc system. The house is a raised foundation style with a 12" to 24" crawlspace beneath.

Twenty years ago I re-wired it with romex as well as other fairly significant projects. I work with chemical process systems, hoses, liquid flow and pressure at work. I don't think this would be out of my reach but want to run it past others.

Suggestions? Cautions?

Thanks in advance.

Todd

[LazyPup]

Both the International Residential Code(IRC) and the Uniform Plumbing Code (UPC) list a number of options for water distribution line (water lines within the structure) materials;

Galvanized Iron Pipe- generally considered too expensive and too labor intensive.

Brass pipe- cost prohibitive and again too labor intensive.

CPVC- often used where they have water quality issues that would effect copper such as high PH levels. In my personal opinion if we have a water quality issue that is eating up the pipes I must ask myself, what is the health risk? would we not be better served to install a water treatment system to correct the problem rather than select a pipe that will tolerate it? The downside of CPVC is that it does not tolerate mechanical stress well and it gets brittle with age.

Polybutelene- Although totally code prohibited under the UPC it is still permitted under the IRC however when we consider the high incidence of failure and the number of class action suites that have been filed as a result of this product I would be hard pressed to even consider it.

This then leaves us a choice between Copper and PEX. Both Copper and PEX have their good points and bad points.

The linear foot cost of copper is much higher than the linear foot cost of PEX so when PEX is used in the Main & branch layout like copper there is a substantial savings in pipe cost, howeve when PEX is installed in a manifold system you have a separate home run back to the manifold from each fixture stub out so you end up using many, many times more linear feet and often the price of the PEX tubing will now be greater than the cost of copper pipe.

Manifold systems have the advantage that if you should have a leak on a line you can isolate that line without disturbing service to the rest of the house but this can also be achieved on a main and branch layout by carefully placing additional line stops as zone valves. On the downside, I find a manifold system can be very inconvenient because they do not install angle stops at the fixtures with a manifold system. This means that if you want to service a toilet or faucett insted of just reaching down and turning the angle stop off you must first go to the basement or utility space and locate the valve on the manifold to turn the water off. Personally I am getting too old for all those extra trips up and down the stairs.

Being rigid copper requires an elbow to change direction where the PEX can easily be bent around a corner. Some argue that this saves the cost of the elbows but in many cases one PEX fixture stub out will cost as much as a bag of 10 elbows. In truth the cost of fittings is often much higher for a PEX system. The singular advantage to PEX here is that there are far less fittings concealed in the walls or ceiling thus there is less chance of a leak from a failed fitting, but then, if the copper was properly soldered and the system pressure tested the likelihood of a fitting failing is slim to none.

PEX tubing will tolerate freezing whereas copper pipe will not, however keep in mind that if the freeze occurs at a fitting on a PEX line the ice expansion will also expand the crimp ring and when the ice melts and the pressure is restored the fitting will most likely blow out. We must also remember that the PEX fitting stub outs are made of the same grade of copper as copper pipe and if the freeze occurs in the fitting it will exhibit the same failure as copper pipe.

Along this same line, some argue that PEX is the material of choice where PH conditions cause pinholes in copper. Keep in mind that the end fittings on the PEX system are also copper and here again, subject to the same degree of failure. The solution here is to ether use CPVC or install a water treatment system.

It must also be noted that code prohibits any synthetic pipe material within 6" of a gas water heater flue so when using PEX or CPVC you will still have either a Copper, Brass or galvanized iron pipe riser on the water heater. (if you use copper you must have a dielectric nipple or dielectric union between the copper and the water heater vessel whereas brass pipe or galvanized iron pipe may be directly coupled to the iron tank.)

For rework such as your project PEX has the advantage that it can easily be pulled through the walls in the same manner as pulling electrical cable. This means that with careful planning running PEX can be much less intrusive. On the other hand, seamless roll copper pipe is also code approved and it can also be pulled through walls.

On the other hand, PEX will not tolerate prolonged exposure to ultra-violet light such as direct sunlight. When running PEX we must be careful to either avoid areas such as near a basement window or in an open crawlspace or we must provide a cover over the PEX

One major downside of running PEX under a structure in a crawl space is that for reasons known only to the critters involved, Rats, Mice, Rabbits and Oppossums have a very high propensity for chewing through PEX tubing.

As far as materials go, PEX is still the new kid on the block therefore most codes have not adopted many strict standards. Instead the codes state that the PEX must be installed in compliance with ASTM (American Society of Testing & Material) standards and manufacturers recommendations. In some jurisdictions they require you to take an approved training course before running PEX but more often than not this is a joke. You can generally get a manufacturers booklet at the PEX supplier, and after you read the book thoroughly you will find a wallet card on the last page which you tear out and sign. Even though it may not be required I would highly recommend you do get the book and read it thoroughly. You will find many important procedures and some helpful tips in the booklet. Typically the booklets are about $5 or less and can be found in many Lowes, Home Depots, Ace hardware stores or Plumbing supply houses.

PEX is not at all difficult to run but it must be remembered that for a potable water distribution system you may only use crimp on fittings that are approved under ASTM standard F-876 & F-877. All joints MUST BE made by means of ASTM approved PEX crimping tools and all joints MUST BE checked at the time of installation with an ASTM approved GO-No Go guage. Typically you will use three different sizes of tubing and each size requires a separate crimper. Currently the crimpers are approximately $125 each and the guage is another $20 to $25 for a total tool cost of about $500 or you could opt to get a Rigid Tool Co cordless power crimper complete with a spare battery, charger and three interchangable dies and carrying case for a mere $2,100.(There are some compression fittings available for PEX tubing and they may be used for hydronic heating systems that typically operate at 15 - 25psi but those fittings are strictly prohibited on potable water systems where the minimum permitted pressure is 40psi).

By contrast for copper all you need is a torch, a tubing cutter, emery cloth, ID brushes and solder. For a torch my personal recommendation would be a Bernz-O-Matic TS-4000 with propane fuel. I currently am using one that i have used commercially for about 8 years and its still going strong. Cost about $40. My all time favorite tubing cutter is a Rigid mini cutter that will handle up to 1". If fits very nicely in a pocket and will handle almost all aspects of residential piping. Cost about $20 but you can get replacement cutter wheels for about $5. I find that i loose it or leave it behind on a job somewhere long before i ever wear one out. Disposable ID brushes are about $1 each and you can get a precut roll of 2" wide x 50' long open weave emery cloth for about $7. Another $10 for solder and flux and maybe $5 for a small toolbox to contain it all, plus the box will keep a few fittings handy. Total initial cost under $100. (less than the cost of one crimper). Many people are resistant to soldering but with a little practice you would find that soldering is not much more difficult than properly gluing CPVC or PVC.

My personal singular reservation against using PEX is a health concern that has not as yet received much public attention. There is a micro-biological issue called "Bio-film". Bio-film is a jelly like mass that can form in water lines. It has the general appearance of clear jello or the meat gelatin that we see in a canned ham. Bio-film has been linked to a number of major illnesses including legionaires disease.

Under laboratory conditions bio-film actually forms the quickest in virgin copper pipe, followed by PEX and lastly in CPVC however, as copper pipe ages it forms a greenish scale on the inner pipe wall that is actually copper sulfate which just happens to be one of the best anti-bacteria agents known to man thus by the time biofilm begins ot develope in a copper pipe system, the pipe has already formed an antidote to prevent it.

Generally biofilm does not form in pipes where the water is repeatedly in motion such as a main & branch layout but rather it forms in dead end runs such as near an outside hose bibb that is seldomly used. This is also why many local codes now require commercially manufactured water hammer arrestors with a membrane instead of field manufactured water hammer arrestor stub ups. The problem with a PEX manifold system is that every line from the manifold to the fixture is a dead end run, therefore the risk of biofilm production is apparent at any seldomly used fixture such as guest bathrooms, basement bathrooms, or a garage utility sink, etc.

With all things considered it could be said that both PEX and copper will provide a high quality job with an anticipated service life of 50 years or more. Personally I prefer the copper but I would have no reservations in recommending either product if it is properly installed.

Hopefuly this will answer some of your questions, or at least provide a bit of food for thought.

[Todd T]

Thanks for the great reply. I can see where it may cost more in some ways but less in others. In my project I'm thinking of doing one room at a time... capping off the old plumbing whenever I convert a device.

My crawlspace is pretty tight in some areas. And I don't trust my sodering abilities very much. I've used compression fittings for years and the pex supplier I'm considering offers really good daily rental rates on the fitting wrenches and go/no-go gauges.

I can see your concern regarding stagnant water. I see the same thing in industrial stainless steel applications where we get microbiologically induced corrosion (MIC) literally eating the stainless steel. Warm, stagnant water is the biggest culprit.

We will have regular and substantial flow on everything except the ice maker. For that reason I may want to do the standard copper jumper from the sink cold water feed just on that device.

I do industrial cleaning for a living. Years ago we designed a recirculation loop to do some chelation cleaning on the buildup in the existing galvanized pipe. I'm sure it would have worked but we may have had swiss cheese for pipes when we were through.

Thanks again for your info. I appreciate your balanced approach listing the pros and cons of various methods.

Todd

[LeeW]

How about Stainless Steel vs. Copper and PEX?

Hi LazyPup:

Have you had any experience using Stainless Steel for residential potable water applications?

I just purchased a new home that was built in 1988, and since I am doing a significant amount of renovation, I decided to replace the copper plumbing. Although PEX would be very easy to work with, the biofilm issue scares me. I do almost all my industrial piping with stainless, and was wondering if you had any thoughts on using 316 ss instead of copper? I don't think biofilm should be a problem since there would be significant flow through the loop, and it should last much longer than copper?

Thanks!

Lee

[LazyPup]

I have no doubt that stainless steel would provide a viable option however we are required to confine our choices solely to the materials currently listed as approved by the code and since stainless steel is not a code option we would not be permitted to use it.

[LeeW]

I wonder why ss is not approved by code? Interestingly, it isn't approved for gas lines either, but we did some gas lines at our facility in stainless, and when the plumbing inspector said it wasn't approved, I told him that was completely stupid and he should approve with an exemption, which he did. It is completely ridiculous that you can use black steel, or galvanized steel, but not stainless.

[HayZee518]

I think the main issue about using stainless is the threading issue. the nickel in the stainless makes for awfully hard threading unless the pipe is annealed. a lot of stainless tubing if not flared with a 37 degree flaring tool can be a problem as the compression fittings just don't want to give in to slight collapse to seal the fitting joint.

[LazyPup]

whenever the regulating authority considers a material for approval there are a number of factors that must be considered.

First and foremost it must be understood that while most building codes insure the safety and durability of a structure the plumbing codes are not building codes. The plumbing code is a health code designed to insure the continued safety of the public water supply and while a violation of a structural code may result in civil litigation a violation of the plumbing code can and often does result in criminal prosecution and jail time.

In regard to health stainless steel has proven to be a very good performer which is evidenced by stainless steel vessels in high end long life water heaters, faucetts, sinks, fixtures, appliances or our cooking utensils.

When considering a material for the water distribution piping we must consider the handling characteristics of the material. In this regard stainless steel presents a number of problems.

Stainless steel pipe is very difficult to thread and cannot be easily welded without special welding skills and very expensive welding equipment.

Stainless steel tubing is very rigid and requires a bending tool to properly bend it without colapsing the tubing wall. While it can be joined by means of compression fittings it is difficult to insure water tight seals and compression fittings are prohibited in concealed locations. Stainless steel can be joined by means of flare fittings but as a rule flare fittings are not approved for potable water systems and due to the rigidity of stainless steel tubing even flaring requires a much better quality flaring tool than what is typically used in the plumbing trade.

While standards could be written to insure the initial installer would have the necessary tools we must also consider that once installed most potable water systems will be maintained by homeowners or semi skilled DIY'ers and there is no way to insure they would have the proper tools or special training required. (This is currently a problem with PEX).

While we could probably find a number of materials that would be suitable we must also keep in mind that the more materials that are approved the more difficult it becomes to regulate how they are used therefore we often see a serious reluctance to adopt new materials.

We must also consider the cost of the material. While stainless steel pipe or tubing might prove to be an excellant material due to the cost by comparrison to the options it is very unlikely that it would receive much acceptance by the general public

[LeeW]

Thanks LazyPup - I appreciate all the time, experience and thoughtfullness you put into these answers!

I understand your points completely - and am certainly aware of the difficulties and expense of working with stainless steel. However, that probably will not deter me. I currently do my own stainless threading and TIG welding. However, I was planning to try the Victaulic PressFit system for this application - do you have any experience with these PressFit fittings?

Anyway, I'm going to ask the local plumbing inspector if he will issue a waiver to allow stainless steel piping - will let you know how it goes.

Thanks again!

Lee

[LazyPup]

I doubt seriously if you will have much success getting a variance. The concern would be that you may have the necessary equipment and skills to maintain a stainless steel system, but should you decide to sell the house neither plumbers in general or the new homeowner would be able to maintain the system.

[LeeW]

Hi LazyPup - just wanted to give you a follow-up.

Spoke to the State of CT building code inspector about obtaining a variance for stainless piping, and it turns out that they use the International Plumbing Code, which already allows stainless steel for all potable water applications.

[dbsmith]

PEX help

Hi there. I had an additional question about Pex plumbing. I am trying to install a sink in a bar and my route to get there is difficult. I found PEX plumbing and using a flexible pipe would be incredible. My question is this; can I join PEX tubing to existing cpvc plumbing? Ideally I would go from the sink with the PEX, up the wall, across the ceiling and across to the existing plumbing.
Thanks for any help!