Competition in the central vacuum business is fierce and is only going to get tougher. As the product becomes a standard appliance to more and more homes (like the garbage disposal did in the 60's), more and more big name manufacturers are going to want a piece of the pie. Hoover, Eureka and Electrolux have given the concept greater acceptability just by putting their name into the pot. Some will even private-label under many different names.
And, ultimately, each manufacturer will tell you, unequivocally, of their preference for either bag-style filtration or cyclonic-style filtration. Within the major built-in vacuum manufacturers you will find claims ranging from "true cyclonic", "self-cleaning", and "100% efficiency at all times" to "guaranteed never to clog" and filters with "no resistance to the air". Herein lies the greatest difference (not to mention, the greatest challenge) of product designs: Which filtration system is better?
Obviously, we feel that ours is a better system. But rather than make arbitrary or dogmatic statements, let us carefully examine the claims each manufacturer makes about their products -- in their own sales brochures -- and then compare this with the information in their own service manuals to see if their claims are really valid!
To begin with, Ametek, the major manufacturer of most central vacuum motors, states specifically in their warranty "...typical signs of abuse...." including "...dirty motors, failure of which was caused by inadequate filtration [Emphasis added]....will not be considered in-warranty failures". Therefore, built-in vacuum manufacturers must adequately protect the fan blades of the motor from debris. To restate the problem: how do you provide adequate filtration without reducing product performance - both short term and long term? Your decision on which brand to promote may change on these all-important facts.
While a few manufacturers may claim it, none utilize "true cyclonic" in which ALL filtration is achieved by the creation of a cyclone which uses centrifugal force and gravity to separate the impurities from the intake air. Vac-U-Flo and Vac-U-Maid come very close to being "true cyclonic", but both have some type of filter as mentioned in their service manuals.
Vac-U-Flo says, "A guard screen is located directly above the dirt pan inside the power unit. It should be inspected and cleaned occasionally. This is to prevent such things as carpet fibre, cloth, etc. from getting into the motor's impeller blades. A build-up of dirt or other larger, clogging-type material may result in loss of vacuum". But, wait a minute! Their own sales brochure claimed "100% efficiency at all times". Both statements can't be true! Furthermore, their service manual goes on to say that, "much excessive, loose lint and nap, normal in all [Emphasis added] new floor coverings, is removed in these early cleanings, and some will tend to settle on the screen, allowing a build-up that will impair the suction power unless removed." How many home owners bother to clean a filter they can't see and/or are not told about. Here is a manufacturer admitting that within the first few usage's, his own product can lose performance.
VAC-U-Maid states in their publications, Introduction to a Built-In Central Vacuum Systems, that they do have a metal screen but, ".....the pores of this metal screen are sufficiently large to insure that no plugging results from normal use. Therefore, you have constant airflow and no loss of cleaning ability." This sounds impressive but their service manual says, "if the screen becomes clogged with lint and rug fibres, it will decrease your vacuum power to a point where you are unable to clean properly due to the decrease in air flow. [Emphasis added]". Again, we have not only a contradiction in claims, but a manufacturer's admission of poor design.
CYCLONIC action does remove the heavy particles, but the light fibres and dust are emitted through the fan blades. VAC-U-Flo does admit that their system will "....maintain up to 98% efficiency. The remaining 2% consist of small particles which are exhausted outside". That's why their service manual states that when low suction exists, ".....the exhaust line may be clogged." Their manual also states that "....overfilling of the unit may cause motor damage. " Likewise, VAC-U-Maid's Manual states: "....overfilling could cause debris to be drawn into the impeller blades which may severely damage your power unit." These cyclonic systems do have a big advantage which they emphasize in all literature: there are no replacement filters or bags to buy or store. This factor may represent as much as a $15.00 retail savings per year.
Most cyclonic units install some type of filter, be it cloth, foam, geotextile, self-cleaning, never-clog cloth, or whatever. While this is to eliminate the need for a paper bag, these units must still provide a certain degree of motor protection. The cyclonic action with a cone does eliminate a high degree of the debris but fine dust and lint are caught in the filter. To maintain maximum performance some manufacturers like Hoover recommend that "the filter should be cleaned every time the dust container is emptied." Or, as Easy-Flo suggests, "To extend the life of your vacuum....change your filter." Beam says, "it is recommended that once a year the filter should be cleaned thoroughly." Again, in the trouble-shooting section of this product's manual you will see as the number one remedy for loss of suction,...."clean out dirt receptacle. Inspect and brush off filter."
Most cyclonics must be vented outside the living areas "...because it eliminates the very fine dust and bacteria not trapped by the system's filter." Let's look again at what Ametek says :"If their filter is too porous, dirt and other foreign material can build up on the fan blades over time [Emphasis added]." "A motor can handle a certain amount of this." says Stormy Greer of Ametek, "but what really causes a problem is when this material breaks away unevenly. When this happens, the vibration in the motor increases. The high speed operation of the motor makes balance critical and as vibration increases, premature motor failures can result. This is one reason we are so concerned about adequate filtration. The amount and rate of dirt build-up on the fans in an inefficient design or unmaintained system can cause problems sooner than a customer expects. When this happens, we all have a problem."
Some bag types lose performance far quicker than others. Those with longer continuous power often support the paper bag with a cloth bag, which allows the paper bag to be made lighter and more porous. This is the method used here with the Silent Master. Others, such as Nutone, use a heavy porous paper bag which, ".....if the bag is filled, you will notice a complete loss of vacuum." For added filtration,, secondary filters are often incorporated which act as a safeguard against bag breakage. Inadequate primary filtering may require that you "clean secondary filters each time the bag is replaced." As previously mentioned, the system used is a very large paper bag which is tapered and supported by a cloth bag. This added filter surface area provides for greater particle distribution and tests with twenty pounds of flour did not significantly impede the flow of air. In fact,. many of our dealers have reported servicing units where the tank was filled to the lid and still had decent suction! Undoubtedly, there was air flow loss but no damage was done to the unit.
Further observations of testing with twenty pounds of flour revealed the turbulent air flow pattern created as debris entered the trash receptacle. The filter actually "cleaned itself" as the air swirled around. (You might like to try this yourself with our Acrylic Lid, Part #97C. it's absolutely fascinating!)
We at Godfreys will be the first to admit that our filtering system will lose performance as the paper bag fills up but we will also qualify that statement with the fact that all systems will have a loss of performance over a period of time. It is our contention that semi-annual replacement of a paper bag is, by far, more efficient with less hassle than the maintenance required to prevent loss of performance and motor replacement costs on cyclonic systems.
For super filtration, where extremely fine particles are being picked up (such as aluminum oxide in dental labs, plastic dust in circuit board manufacturing, or sanding debris in auto body shops and marble polishing), a combination of the above systems has proven most effective: a cyclonic separator is first installed to remove the large debris and then a separate paper bag filtration unit catches the fine particles. A "micro-filter" can also be installed which filters down to .1 micron at a 99.7% efficiency. This will certainly minimize motor failure. Obviously, however, the finer the filter, the quicker the loss of performance.
To summarize any filter you install (screen, cloth, foam, paper, etc.) will impede air flow in some manner. On the other hand, "you need filtration to protect the motor. It's like trying to go swimming without getting wet." - You can't do one without the other.
Maximising the Value of your Purchase
To maximize your investment in central vacuums, and to help you determine which system best suits your filtration philosophy, approach each manufacturer and ask them to answer the following questions:
Which of the above filtering types do they favour and why?
What happens if the system is overfilled?
What annual and/or maintenance expenses can be incurred on this product? (Foam filter, bags, cost for new motor, motor-life expectancy?)
Is exhausting the unit outside necessary? Why?
What would twenty pounds of fine dust do to the system? How much of it would be caught in the filter system and how much would get by to be blown through the motor impeller blades out the exhaust?
If manufacturers of automobiles and central air conditioners feel it necessary to install air filters to filter the air you breathe every day, should it be more important to filter the air that is combined with trash and dirt before it exhausts through your vacuum motor and back into your home? Or, outside?
How messy is it to empty the canister and clean the filter? (Including screen, cloth, foam, or paper bag.) Have them actually change a dirty one right before your eyes.
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