Central vacuum tubing was once cast iron, thank goodness things have changed. The size of vacuum tube has also changed
over the last century and the universal standard in the USA is 2" vacuum tube. This differs from schedule 40 plumbing tube (DWV - drain, waste, vent) which is about 2.21" ID. Both tubes are made from the same material, PVC (poly vinyl chloride). Vacuum tube is much thinner and easier to work with, and the inside of vacuum tube is designed to be perfectly smooth for optimum airflow. The thinner material in vacuum tube design is easy to cut and shape a vacuum system with.
SCHD40 tubing is not used in vacuum systems for many reasons, but the similar size and highly available nature of DWV tube
obviously inspired more than a few do-it-yourselfers who had the desire for central cleaning but lacked the materials.
Since internet shopping has made all things available to all people the interest in SCHD40 vacuum systems has waned.
Some folks still remain interested and still more promote using DWV tube for vacuum systems. Unfortunately not all of the information you find on websites about DWV vacuum systems is completely accurate and much of what you find online is opinion and conjecture. Which tube system is best for the job can only be known by the installer. Start you consideration with good information, which we try to discuss here, and you are on the way to finding the best materials for your job.
COST: Vacuum Tube Vs. SCHD40 DWV
Cost is a consideration in most every part of the jobsite, vacuums included. And for some builders and contractors that buy large volumes of tube the pricing might differ form what the rest of us pay at the local home center. For most of us the cost is a non-factor in the choice of SCHD40 tube or vacuum tube. Our pricing surveys show the average pick-up cost of SCHD40 tube is about $85 per 100ft.
The cost of vacuum tube is similar - about $90 per 100ft. Add to pick-up pricing the cost of time, fuel and state taxes and most times the purchase price is a wash. The cost of vacuum fittings is usually much less than plumbing fittings, some by 50% or more. Again adding the cost of your time, fuel and local taxes and the SCHD40 tube system could cost a bit more depending on your purchase volume of plumbing tube.
Code compliance enforcement varies from state to state. Some local code inspectors that once ignored the materials used in CV Systems now look for the ASTM F2158 mark and UMC approval shield. 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. This standard for central vacuum installation materials is part of the UMC (Uniform Mechanical Code) and valid for all 50 states. 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. In many areas new construction central vacuum systems are not inspected, particularly DIY's and retro-fits.
Vacuum System Performance
There has never been a report, study, research or even a guess from any vacuum systems manufacturer or accredited independent review which suggest that using SCHD40 will increase or decrease the overall vacuum systems performance. All Central Vacuum manufacturers recommend using vacuum tubing. All specifications and performance comparisons of vacuum systems are based on the assumption of vacuum tubing systems. While it seems simple to assume that bigger tube is always better for airflow, the simple answer is often not the simple truth. The airflow volume of all vacuum systems is limited by the smallest diameter passage. SCHD40 tube systems must use reducers to connect with standard 2" vacuum inlets and the vacuum power unit. Combine the limiting factors of SCHD40 tube and the limitless variations of systems and the end result may be better, could be worse or might be exactly the same. Without an authority to do proper testing we have only assumptions about system performance when using any materials other than vacuum tube.
Vacuum tubing systems are not structural, support no weight and holds no real pressure. Vacuum tube is thin walled and lightweight by design to make it much easier to handle and install. SCHD40 tubing is considerably more heavy, harder to cut and debur and less flexible when installing in tight spaces with shorter pieces. Each type of tube is designed for it's own special purpose and built accordingly. When it comes to vacuum systems the lightweight vacuum tube is clearly the preferred choice.
Long Tube Lengths
Long lengths of tube seems important to those that have yet to install their first central vacuum system. The need for making one long continuous run of tube is rare. Well designed installations are compact and make use of every run to add inlet drops or truncate the system. Most tubing in vacuum systems are sections of five feet or less. The super massive twenty-feet long tubes are made for burial underground in plumbing and sewer systems. Tubing installed within the walls of your home is small sections connected with elbows to form a compact cleaning system. As we train our new installers we teach them a simple concept that helps them to focus on the task; install the inlets, not the tube.
Clog Resistant Tube
Someone who would suggest SCHD40 is anyway less prone to clog is likely ignorant in many areas of central vacuum systems. A properly installed system using either type of tubing is impossible to clog in the normal cleaning of your home. Yes, there is that "normal" catch. Golf balls, hot wheels, dish towels, trash bags, sheetrock screws and peanut butter are not normal items to be cleaned with your vacuum system. Accidents can happen and in the extremely rare case of a system clog the design allows for easy self service in most every case.
Vacuum Tube or SCHD40, it's up to you.
Many parts of the central vacuum systems has changed in the last century, from the vacuum tube to the vacuum motor and the attachments we use to clean our homes. Just in the last decade central vacuum equipment performance has increased 30% while cost of ownership has decreased. More airflow and suction can lessen the requirement, from a performance point of view, for using only vacuum tubing. Todays stronger motors and better cleaning tools and hoses can overcome deficiencies in SCHD40 tubing used in airflow systems. While most systems will continue to be installed with vacuum tubing and fittings, SCHD40 tube systems are available for those that need or want them.
There was a time when we strictly opposed the use of any installation material other than vacuum tube. Every installation and every customer is different and Vacdepot will work with customers to support any central vacuum installation. We prefer and recommend vacuum tube for most systems and we use vacuum tube on all systems we install, however we happily offer both for our customers convenience. We always believe that selling and installing ASTM vacuum tube is a requirement of every reputable installer-dealer. Vacdepot will always encourage the use of vacuum tube and we will support our customers which ever tube system they choose. Our mission remains the same, promote central cleaning systems as the most reliable way to clean and maintain your home while also reducing indoor allergens. Central cleaning systems are the superior method to vacuum your home and the means of installation is less important than the resulting benefit to your family. Central vacuum systems can be both fun to install and fun to use in your home. You can do it, we can help.
An Original Vacdepot Article. © 2014