There are still a few self-purported central vacuum professionals promoting the use of plumbing pipe designed for water or liquid waste as good idea for your new central vacuum system. The main point of the idea seems to be that it will save you money in initial cost of the pipe, more on this later. This novel but bad idea completely negates the work of companies that built the CVS industry like Hayden, Canplas (Vaculine) and HP Vacuflo. These international companies have spent decades of man-hours and untold numbers of dollars to research, design, manufacture and distribute fittings and pipe made specifically for residential built-in vacuum systems. And when it comes to something built-in your home behind the walls that can not easily be undone whom would you rather trust; the companies who built the industry and the professionals whom run it now or a sales person or website trying to make the deal by supposedly saving you a few bucks with a secret tip.

The Secret Is Out!
You have listened to the sales pitch, and it's all making sense. The government doesn't "really" have the right to collect taxes. Dropping special magnets into your gas tank will get you 5 more miles to the gallon. And using plumbing pipe from your local home improvement warehouse will save you the big bucks on your CVS install. The idea of getting one over on the man by using a substitute or replacement material to save money is not a new idea, but can you really save money using water pipe for your vacuum airflow system?

Compare the price as we did October 2006 in our home town, Fort Worth Texas. We called 6 area plumbing suppliers and home improvement warehouses for a 10 ft, 2" diameter section of SCHD 40 water pipe. The cost ranged from just over $7. up to $10. each with tax. Ten sections of pipe; 100 feet in total will cost you $85. on average in a mid to large market city. This does not include your personal time to purchase the pipe or gas to drive to the store - just the cost of the pipe. And unless you have a truck or trailer you might need to cut the pipe to drive home or somehow fashion the pipe to the roof or out the trunk of your car - not exactly convenient.

Vacdepot offers our CV-T100B bundle of central vacuum pipe for $89. Our pipe is ready to install, requires no special adaptors (which makes the system future proof) and includes delivery to your door or worksite in packaging that protects the pipe from bends, cracks and chipped edges. Water pipe fittings also cost as much or more than vacuum fittings. In example a 2" 90° water pipe elbow is $2.00 versus $1.14 for a 90° vacuum sweep elbow (also called a long or airflow radius ell).

Don't forget to add to your cost the price of those special adaptor-reducer connectors and your savings have easily surpassed the cost of using the correct materials. So if you cannot save money using water pipe and fittings, what possible good reason could there be to use the wrong materials in your brand new home? Could it be there is a reason that someone may not want to sell you ASTM rated CVS tubing? We tell you the truth as we see it later in the article under the section titled "Selling CVS tube is not fun".

This article specifically addresses the idea of using 2 inch SCHD40 tube inside a residential attic and/or basement and walls for homes under 18000 square feet. There is however an application for 2 inch SCHD40 tube in central vacuum systems, those systems requiring direct burial. When vacuum tube must be run in-ground and can not be inside a protective housing it must be converted to 2 inch SCHD40 tube. Regular vacuum tube is not designed for direct burial and could be damaged or crushed by the pressure of a slab poured over top or heavy vehicle traffic. Most often this is used in homes with a detached garage or some special needs retrofit applications. Commercial applications do not require 2 inch SCHD40 pipe. Most commercial applications are fitted with all steel tubing instead of PVC due to commercial building fire codes.

A New Standard - ASTM F2158
Maybe money is not the issue and you still think that using plumbing pipe for your central vacuum is a good idea. Before you start the CVS project you might ask another group of folks - your local code inspectors. Some local code inspectors that once ignored the materials used in CV Systems now know to look for the ASTM F2158 standard that is marked on them (only CVS tube is marked with F2158, not water pipe). If your using the wrong materials, or materials without the correct ASTM markings you may be required to pull all of the unmarked pipe and fittings out and start all over again. Vacdepot sells only the best ASTM-F2158 2" CVS tube from Jabat plastics, the number one USA manufacturer of CVS tube with the IAPMO tested UMC (Uniform Mechanical Code) approval shield. Although nothing can "guarantee approval" in areas where CVS tube systems are inspected the UMC Shield lets the inspector know at a glance you are using the materials specified in the UMC for the job.

Ok, so we know plumbing pipe is the wrong material and we know you will not save money using it, so why would anyone think this was ever a good idea? Lets examine their claims in some detail.

"Water plumbing PVC pipe will increase your CFM"
It is important to know that those suggesting the use of plumbing pipe are not suggesting that the entire CV system be changed to 2 inch pipe, just the parts in the middle between the power unit and the valves - what's called "intrasystem". There is no study showing that using 2 inch (SCHD 40 pipe is 2.21" id) plumbing pipe will increase your CFM (cubic feet per minute of airflow) any better than true CVS tube in a vacuum system. What's more the intake orifice of a CVS motor is 2 inches, and all machines are fitted with standard couplings for the intake and exhaust.

The true working orifice of a central cleaning system is 5/8" up to 7/8" in diameter on average. Imagine an hourglass with its sand slowly passing through the restricted orifice in the center. Making the area larger on top or larger below the center of the hourglass will not make the sand move any faster through the small center. The number of cubic feet per minute (volume) in a CV system is limited by the smallest diameter passage in the vacuum system. Using larger ID pipe with small reducer couplings limits airflow throughout the entire system and creates a bottleneck when the air stream must be "reduced" to enter the power unit.

Another important factor of tube performance is its interior design. CVS tube is built differently than water pipe in it's interior wall construction (smoothness of the tube). This point was mentioned on a beginners do's and dont's list in our trade publication; "While some installers use schedule 40 plumbing tubing and elbows in place of central vac tubing, doing so actually reduces the efficiency of a central vac. Plumbing tubing has rough inside wall surfaces and tight elbows that restrict air flow, encourage clogs and reduce suction." - Dave Schenk, OEM Products Manager for H-P (VacuFlo) Products and a 31-year veteran of the vacuum industry from the November 2006 issue of Central Vacuum Professional trade magazine.

"Water pipe is much thicker and stronger than CVS pipe."
Using the same logic you should also use 1" thick glass for all of the windows in your home, but where's the benefit? A CV tubing system is not structural, supports no weight and holds no real pressure. CVS pipe is thin walled with very lightweight properties that make it much easier to handle and install. Using a material that may be 2 - 5 times the thickness and weight is not required for the application, is wasteful of material, resources and our environment. Not to mention the extra effort to install heavier less flexible pipe.

"Water pipe comes in lengths up to 20 FT requiring less cutting and gluing"
Long lengths of pipe always sound like a smart idea to someone whom has yet to install a CV System. Our professional installers carry only 5 ft. and 8 ft. CV pipe sections with them. The need for making one long continuous run of pipe is rare and best to avoid when possible. Well-designed installations are compact and make use of every run to add inlet drops. Our installers find that 65% of the pipe we use is sections 5 ft. or less between the fittings. The idea of using long runs of thick PVC water pipe is actually a tool we use to help train installers at our Central Vacuum Depot store in Fort Worth, Texas. The lesson is simple; Work Smarter, Not Harder.

"Water pipe is less likely to clog"
This comment borders on fear mongering and only serves to show a bit of ignorance on the subject. Water Pipe, because of its design (it's built for water!) is much more likely to clog when used for a central vacuum system. A properly installed CV system using airflow fittings is entirely unlikely to clog. Our repair crew does go on a few clog calls every year and finds of systems with a good installation the clog is where it was designed to be.

CVS pipe and fitting manufacturers do not design their product to clog, but in the extremely rare case it should happen the clogs are accessible and removable once the walls are finished. Water pipe fittings have no such design and may clog in an inaccessible wall or attic. The guys making water pipe never thought how it might work for your central vacuum systems' airflow. That was never the products design. PVC pipe is not all the same. One look at the ASTM description of both and you might just be amazed how much two items made from the same material can be so different.

It's not fun selling CVS tube.
If someone tells you it's OK to not use ASTM central vacuum tube, they must have a motive or reason. While we do not know anyone's true intent we can venture a guess as we are in the same industry. For a company like ourselves to stock pipe in quantity is expensive and a real hassle. The special boxes we use for shipping are also expensive and hard to store. The pipe, which is purchased in bulk form, must be repackaged in our warehouse, which is very labor intensive and expensive.

Shipping is also expensive for pipe, which ships based on the size of the package, not the weight. Often the packages are rated at dimensional weight of 80 lbs which can cost over half the sale price with Vacdepot's free shipping program. It would be less of a burden on our company to suggest a customer use water pipe in their installation and just purchase the valves and fittings from Vacdepot - "to help you save money".

As a do-it-yourself consumer you rely on and expect advice and guidance from the professionals selling you the equipment. And we suppose it would be easy to suggest using water pipe when there is no future liability of system performance. Nobody can guarantee the performance of water pipe for an airflow system, and if you do have trouble with your system who are you going to call for help? The great folks who suggested you use the wrong materials? Or perhaps the company that sold you the water pipe that you then installed for the wrong purpose? You can see where neither company would be inclined to help. When you use the wrong material for your installation and either have to rip it all out or must fix it later, then you the installer are the only one responsible. Selling and installing only ASTM Vacuum tube is a requirement of a reputable installer/dealer, not an option. It may not easy and may not be profitable in some sales but it is always the right thing to do. Don't let your dealer push you into an option that is more comfortable for them and not better for you.

With exception for direct burial pipe (vacuum pipe buried underground) we do not recommend the use of 2 inch water pipe. We stock only Quality ASTM-F2158 IAPMO UMC CVS Pipe and fittings. It does not matter where you purchase CVS Pipe and fittings, they are quite popular and you can find them many places on-line and locally. Though if someone suggest that you can save a few bucks by using water pipe for your vacuum system don't just walk away - RUN!

An Original Vacdepot Article. © 2008

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