Thursday, April 30, 2015

Motor burnout danger

Every central vacuum power unit -- actually, every product -- has good points and bad points about its design. Trade-offs are unavoidable in life. Sometimes though, a simple and easily corrected design flaw can become a hazard.

Such is the case with certain central vacuum power units, having flat tops with unprotected motor intake vents. This issue occurs in certain models of brands such as:


With this design, there is nothing stopping an object placed on top of the central vacuum unit from restricting the motor cooling airflow, leading to motor failure. Power units that use disposable bags are especially susceptible to this problem, since atop the unit seems such a sensible place to store extra bags!

Here's an example of a unit as I found it:

This machine is an Astro-Vac, which uses disposable plastic can liners. The owner's manual and spare can liners had been blocking the motor intake vents long enough that the heat from the motor had melted the plastic and started to scorch the paper. The owner was amazed to see how lucky she was that this was found in time, and how close she came to needing a new central vacuum unit (or worse!)

Units like this are not inherently dangerous, as long as you, the owner, are careful not to obstruct the cooling air vents by placing anything on top of them. I have even taken a marker (or you could get fancy and use a label maker) and written a warning in big letters.

If your machine has only a lid on top, and its motors are mounted on the bottom (like Filtex, MD, SilentMaster, Air-Flo, etc.) then it is perfectly okay to continue storing bags on top of the machine -- in fact, that's my favorite spot for them. When in doubt, however, the safest rule of thumb is not to place anything on top of your vacuum, and keep objects clear from the sides, too -- this promotes better cooling, and longer motor life.

Saturday, February 14, 2015

Updating Kenmore Central Vacuum Inlets

If you have an older built-in vacuum system, you may be prevented from upgrading your attachment set if a newer, “industry standard” hose will not fit into or activate your wall inlet valves.

You can read about various older, non-industry standard wall inlets used through the years here. If the tubing size was the same or larger than modern wall inlets, and especially if the screw spacing of the mounting plate lines up, then modern wall inlets can be adapted without too much trouble. But what can be done if the old inlets and tubing are smaller than modern inlets? New inlets simply won’t fit, and you can’t just “get a bigger hammer” as my grandfather would say.

This is a common dilemma with Kenmore central vacuum systems, which have existed since the early 1960s, and used a small, non-standard tubing system until the 1980s. Here’s an old Kenmore wall inlet:

This is one of the earliest types, that required manually activating the power unit. Since the unit was being replaced with a modern machine, the inlets needed to be changed. First, let’s remove the two screws and take off the old plate, taking care not to damage the paint:

This particular inlet is installed on a paneled wall, but the process for a more typical sheetrock wall is the same. First, we’ll enlarge the opening to a rectangle the size of the new inlet mounting plate, about 4 1/2” tall by 2 1/2” wide. Then we’ll need to dismantle the old metal mounting plate, leaving only the flanged 90 degree elbow. If the plate is attached to a stud (indicating the system was installed during construction), some careful work with a reciprocating saw is usually the best way to remove it. And no, that’s not an oxymoron. Keep your tool under control.

Now, the flanged 90 degree elbow needs to be removed. The best tool to cut the pipe off where it meets the elbow, without damaging either side of the wall, is a cable saw, available in the plumbing department of your local hardware store:

It’s likely the pipe will have some up-and-down play in it, so take care not to dislodge a fitting downstream. If you are able to move the pipe to cut it off past the elbow, all the better. Of course, it’s important to make a nice square cut and remove any burrs with a utility knife, sandpaper, or a deburring tool.

Once you have the end of the old pipe prepared, you can cement on, in succession, an adaptor, a short (1 1/2”) section of 2” vacuum pipe, a tight 90 degree elbow, and an inlet mounting plate. It’s likely some curse words will be involved in this process, especially if this is the first one you’re doing. When finished, you’ll have something that looks like this:

In the picture above, the low voltage wire has already been stripped and bent to fit around the screws of the new wall inlet. We are using the VacuValve inlet, which is large enough to cover any paint lines from the old inlet, plus attractive and durable. The finished product is shown below:

This inlet is now complete, ready to accept any standard non-electric, low-voltage, or pigtail central vacuum hose. Along with the replacement power unit, these changes brought new life to a decades-old central vacuum system!

Thursday, July 17, 2014


Frequently, I deal with issues related to condensation in central vacuum piping. Signs of condensation issues include:

-Low suction from upstairs inlets

-Moisture present in central vacuum unit

-Liquid or “brown goo” dripping out of central vacuum inlets

-A distinctive, nasty mildew smell

Condensation issues occur when the vacuum pipe transitions from a heated living space to an unheated attic. During the winter, warm house air contacts cold attic air, with condensation forming on the warm side (inside the pipe). Though many central vacuum installations involve running piping through unheated areas, condensation only becomes an issue in some cases:

-The difference between the living space temperature and attic temperature must be significant…aggravating factors include running the pipe above the attic floor and insulation, an unusually cold attic, and/or an unusually warm living space

-Dripping from the inlet only occurs when the attic tubing slopes down toward the inlet, causing the condensation to drain to the lowest point

Obviously, this is a problem you want to avoid dealing with. When installing vacuum systems in new construction, piping should run down to the machine if at all possible, rather than up-over-down. Many new construction central vacuum installations (especially those performed by firms whose primary work is electrical or low voltage wiring) have the second floor inlets running up into the attic, then connected together into one pipe that runs down to the machine (sometimes in an exterior wall!). In 99% of new construction work, it is possible to bring the piping down from the upper floor inlets.

Retrofitting vacuum systems to existing homes requires a different approach, making use of the access that’s available. Sometimes, upper levels are small enough to allow full coverage from just one inlet. In this case, try to locate the inlet where piping can run straight down. Make use of stacked walls, stacked closets, cold air returns, laundry chutes, etc. Time spent exploring the way a home is constructed will definitely pay off.

If servicing the second floor requires piping to run through the attic, keep the piping as close to the heated space as possible, and build up insulation in a mound around the tubing. Make a “trap” at the top of inlet risers so that, if condensation does ever form, it doesn’t reach the inlet:


Note: Let’s all take a moment and be thankful that my central vacuum installation skills are better than my MS Paint skills.

Of course, never install a tee or wye branch at less than horizontal, which allows dirt to fall down into inlet risers. Also, wye fittings are always preferable to tee fittings (see my blog post on the differences here).

Often, condensation problems with existing systems aren’t addressed until they’ve become bad enough to cause a loss of suction from buildup in the piping. If the blockage is not severe, usually strong reverse flow (from a high-pressure central vacuum or special unclogging unit) will remove it through the affected inlet.

Even if the blockage can be removed this way, the piping should be visually inspected. Plan to replace and reroute piping if any of the following conditions exist:

-Flow is not proper (tight turns, drop-out tees/wyes, three-way tees, etc.)

-Piping slopes down to inlet

-Piping runs elevated instead of tight to joists

-Buildup is severe (indicated by a measurable difference in working vacuum between upstairs and downstairs inlets, even after main clog is removed)

For lighter buildup, sometimes “TornadoPower” central vacuum maintenance cloths will improve the flow, though they may also turn a partial clog into a full clog and require manual removal.

I have had some success with vacuuming absorbent, slightly abrasive materials through lines with buildup issues. Dry rice is often recommended, though a material like Oil-Dri, non-clumping cat litter, or even silica gel crystals might work well. The more the better.

After piping repairs have been made, insulation is critical to preventing the problem from reoccurring. The insulation should be a barrier between the piping and the attic temperature, NOT the living space temperature. In other words, the goal is for the pipe to assume the temperature of the heated living space as much as possible.

The approach shown below right, as if a “pipe wrap” type of insulation were applied over elevated attic piping, is not effective. Below left is better, though care should be taken to reduce the amount of insulation between the pipe and the heated space, and increase the amount separating the pipe from the unheated attic.


If the tubing runs parallel to joists, try to install it next to the drywall ceiling, then cover with insulation. If (as is more common) the tubing is running perpendicular to the joists, then fiberglass bat insulation can “inchworm” over the pipe, allowing the pipe to sit in a pocket of warmer air.

It can be difficult to eliminate the odors related to condensation issues right away. Odors will diminish over time once new condensation and debris buildup is prevented from forming. Be sure all inlet covers seal tightly when not in use, and exhaust the power unit outside to eliminate odor at the unit location. Fragrances can be used in the central vacuum piping and power unit to mask the odor until it dissipates.

We offer free estimates to homeowners in the Chicagoland area who may be experiencing the above issues with their central vacuum system. Contact us at, or call 630-608-0175 for more information.

Saturday, January 4, 2014

Melted Electrical Plugs


More than a few times in the course of my travels, I have seen central vacuum power units whose electrical plugs had melted. 


Often, this happens on older machines with heavy electrical consumption.  My remedy in the past had been, after verifying the motors were not drawing excessive current, to simply replace the power cord.  I might have plugged it into the other (non-heat damaged) side of the duplex outlet, wished my customer “happy vacuuming” and been on my way. 

My more recent discovery is that the receptacle itself is most often the root of the problem.  Of course, the power cord must still be replaced, but replacement of the receptacle is a critical step.  Over time, older receptacles lose their grip on plugs, and a poor internal connection will cause problems when high-current appliances are used.  The replacement receptacle should be heavy-duty or “spec grade”, and wiring connections should be made properly using screw terminals, NOT push-in “back stab” terminals.  Also, be sure to orient the receptacle, if possible, in such a way as to minimize strain on the power cord and plug.

A good quality replacement receptacle and power cord will safely carry current right up to the rated amperage limit of the circuit, indefinitely.  As a final note, it is always recommended to connect the equipment directly to a receptacle, not through an extension cord or power strip.  Extra receptacles can be added by a qualified electrician.

Get in the habit of giving your built-in vacuum unit the “once over” when you empty it.  If you see something that needs attention, visit or call (630) 608-0175 for a free, friendly evaluation.

Sunday, December 22, 2013

Filtex Central Vacuum Systems


The Filtex Corporation began in the 1930s in Los Angeles, making a tank-type vacuum cleaner similar to Electrolux.  Their first models looked like this:


Most every portable vacuum manufacturer made a unique set of attachments to go with their vacuums.  Filtex was no different, and their attachment set (including patented “Rollex” carpet tool) was one of the finest:


During the 1950s, as lightweight PVC tubing, modern low-voltage controls, and small but powerful universal-type vacuum motors combined to make residential central vacuums a much more affordable concept, Filtex became one of the pioneers in this field.  The power unit they manufactured was called the “Perma-Vac”:


A distinguishing mark of all Filtex machines is the casting on the lid, which is actually an airflow duct which directs debris into the bag.  It also incorporates a utility inlet valve for cleaning near the machine.  This lid casting allows the bag’s cardboard rim to rest at the top of the canister, instead of on a rim several inches down as with competing designs (Modern Day and Central Vac International).  While this makes emptying easier, the tight bends can clog easily, and reduce airflow at a rate equivalent to 40+ feet of straight pipe:


Initially the Perma-Vac unit was made concurrently with Filtex tank vacuums.  However, soon thereafter, Filtex stopped production of portable cleaners, and focused their entire business on built-in vacuum systems.  The Perma-Vac, with its single small motor, only worked well in small homes with two or three inlet valves.  The machine could be ordered with or without a low-voltage control, which used a doorbell button at each inlet to start and stop the machine, and a light to indicate when it was running:


By the late 1960s, Filtex had several machines available to handle larger installations:



The “NMC” logo on the nameplate above stands for Natter Manufacturing Corporation, which had purchased Filtex years earlier.  The company was now based in Temple City, California, where it remained for nearly twenty years.  In the early 1970s, “VSI” started appearing on the nameplate – this was now the parent company of Natter Manufacturing.  Units also changed to a lighter blue color, and more models were introduced:



Those who purchased Filtex systems now also had a choice of “Pushbutton and Light” inlets (which used a latching relay) or “Automatic” inlets, which turned on when opened and used a more standard relay.  Automatic inlets soon became standard and it wasn’t long before the pushbutton-and-light inlets were discontinued.



Filtex whole-house vacuum units looked largely the same throughout the 1970s, with the exception of two changes made in the mid- to late-seventies: the heavy aluminum airflow duct casting on the lid was changed to plastic, and the large chrome lid latches (which were hold-overs from the Filtex tank cleaners of the 1950s) were replaced with small, off-the-shelf toggle latches.

In 1980, the company was sold to Fairchild Industries, which moved production to La Verne, CA.  Machines made in the early 1980s show this address on their nameplates.

Several years later, Fairchild sold Filtex to Music & Sound, a Dallas-based manufacturer of home radio intercom systems.  Mid-eighties units will say “M & S Filtex” in script on the logo.  Several new models were introduced at this point, including their first enclosed dual-motor units (TSP700L) and their first triple-motor units (TM285L) which were inspired by MD Manufacturing’s triple motor units which had been successfully used in larger installations for several years already.


The late 1980s saw several significant design changes, and the new models had an “N” at the start of their model number: NTM285, NTC600, NTSP700, and so on.  The large machines that used to require a 120-volt, 30-amp circuit were now configured to run on a 240-volt, 15-amp circuit.  Parts like the bottom motor cover were now molded plastic instead of sheet metal, and the lid/bag gasket design was improved for a more positive seal. 


Around this time, a cost-saving decision was made to discontinue the metal Automatic inlet valves, and the metal Filtex attachments.  This shift toward off-the-shelf inlet valves and attachments took away a big part of the uniqueness that distinguished Filtex from competitive systems.  The units, which had been light blue since the early 1970s, were painted very dark blue starting in the early 1990s:


You can tell a mid-1990s machine by its “FX” model number (FX500, FX775, FX900) and the new Filtex logo:


Another color change came in the late ‘90s, to a very light gray.  This coincided with the purchase of M & S by Chamberlain, manufacturer of garage door openers and other products.  Also at this time, nearly all dual motor designs were replaced with single motor units (FX2000, FX3000, FX800), the only dual-motor machine being the 240-volt FX900.  This was done as new motor technology allowed a single high-efficiency motor to produce cleaning power that previously was available only in a dual-motor design.  At the same time, the large flocked secondary filter was replaced by a very small (2 1/2” square) hidden filter that would plug with fine dust, greatly restricting airflow. 


The early 2000s saw the Filtex name completely eliminated.  Machines remained unchanged, but now bore the label “AirVac”.  This brand had been manufactured by M & S since the mid-1980s, and up until this point was a line of bagless units with either one or two motors, and foam (later cloth) filters.  After the brand consolidation, rather than “Filtex” being a bagged machine and “Airvac” a bagless as before, the Airvac “Blue” name now indicated a disposable bag unit, and “Red” were the bagless models.  A new “Gold” series offered extra-quiet operation, and system monitoring technology that would flash an LED on the machine and at the inlet valves when service was required. 


Around 2006, production in Dallas, Texas ceased, and the entire model range was discontinued.  The new AirVac Red (bagless) and Platinum (disposable bag) machines are no longer made in the United States.  Though several models are offered for different home sizes, the suction performance is very similar, and all models (even the 240 volt machine rated for 12,000 square feet) have only a single two-stage, 5.7” non-serviceable motor.  While good performers, the quality of these machines makes it apparent that their lifespan will be measured in years, not in decades.


Today, very little remains of the Filtex Corporation.  The units produced by its descendants bear no resemblance to those on which the company’s reputation was built.  Fortunately, Just Central Vacuums has a full stock of parts and supplies to keep old Filtex central vacuums working for decades to come.  Visit or call (630) 608-0175 for help with your vacuum system.

Monday, June 24, 2013

Attic Piping


Recently, I was called out to evaluate a Eureka central vacuum system in Naperville, IL.  The owner indicated that the system “just didn’t work right” and she wanted me to check it out and see what was wrong.  Inspection of the piping system revealed a very poor installation.  Look at the way the piping for the second floor inlets was routed through the attic:


Where to start…first, the fact that the pipe is running about a foot off the surface of the joists makes it difficult to maneuver around, difficult to insulate, and prone to sagging (as evident in the gray piece).  The tee connection to the right of the photo is a “drop-out” (we can assume the installer was also) – it allows debris traveling to the power unit to collect in the branch line below the inlet.  Fortunately, since many of the connections in this system had never been glued, this was easy to correct:


Fixing this involved cutting the risers to slightly below the surface of the joists, then gluing 90 degree elbows in place.  Note the horizontal 90 elbow leading into a 45 degree wye: This arrangement ensures no debris remains in the tubing system, reducing the potential for clogs.

Not shown is the final step of adding loose fill insulation to cover the pipe, which prevents condensation buildup in the wintertime.  Much easier now that the pipe lays flat on the attic floor. 

Here’s a shot of one of the basement lines from the same system:


Not one, but TWO drop-out points for debris to collect.  Dirt would pour out of the inlet on the left whenever it was opened.  I didn’t take an “after” shot once the tubing was re-done properly (nor did I document the many tight 90-degree turns that were taken out and replaced by the proper sweep 90s), but needless to say, this system is working much better now.

Wednesday, May 8, 2013

Inlet Valves, Pt. 2: Non-Standard Inlets

In the past and even today, some inlets are used that do not fit the industry standard form factor of the inlet valves in Part 1.  Here I will cover some of those inlets, their features as well as how to update them to modern, standard inlets.

The very earliest central vacuum inlets were just terminations for the piping, without any electrical contacts to activate the system.  Up until the 1950s, systems were installed with threaded iron piping, and inlets were similarly threaded into the piping.  Here are two examples from early 1900s systems:

Vacuum Outlet246761790_f54162ddf6

It would be theoretically possible (though not often attempted) to adapt modern inlets to the threaded pipe size and run low voltage wire for activation of a modern system.  These older systems were turned on from a central point and designed to run continuously until cleaning was completed, similar to the way large commercial systems of today are operated.  A modern residential system should make use of low-voltage wiring or a wireless remote control.

Starting in the 1950s, small but powerful universal motors and lightweight, low-cost PVC tubing combined to make central vacuum systems a much more affordable option that began to be included in homes of all sizes.  One early pioneer, Filtex, made a very popular, high-quality system and manufactured their own inlets and attachments.  The original inlets used in the 1960s and occasionally seen into the late 1970s had a round door, with a momentary pushbutton to start or stop the power unit, and a light to indicate when it was running:


A nearly identical inlet was used by Central Vac International during the same time period, though there were slight cosmetic differences.  Many times when putting a system into a house that was already built, installers would put these in the floor, as shown here.  If the family pet walked over the button, the system could run for hours before it was discovered, causing the motors to overheat.  This concern, plus cost and aesthetic considerations, caused Filtex to develop the simpler Automatic-type inlet:


This inlet was usually supplied in painted ivory, though stainless steel, polished brass, and antique bronze were available too.  It had a plunger switch inside that turned the system on when the door was opened:


Many, many systems in the Chicago area use this type of inlet.  Most modern central vacuum hoses fit loosely and can pull out, but we stock a hose that fits perfectly and is much lighter weight than older hoses.  Just make sure when calling to mention that you have a Filtex or Air-Flo central vacuum system to get the proper hose. 

Both styles of Filtex inlets can also be easily replaced with industry standard covers, which turn on when the hose is inserted, and allow the use of convenient low voltage hoses having a switch right at the handle. 

Another pioneering central vacuum manufacturer starting in the 1960’s was NuTone, famous maker of door chimes, bath fans, intercom systems, and other built-in home conveniences.  From the beginning, NuTone manufactured their own distinctive inlets:


These inlets, still used today, are notable because of their nearly square shape, screws on either side of the neck, and an inside diameter just slightly smaller than the industry standard 1 1/2” – enough of a size difference to cause standard hoses to fit too tightly, and not bridge the contacts to activate the system.  It is relatively easy to change these inlets to standard Hayden or Canplas inlets, but CycloVac Deco inlets are especially easy to retrofit.  As an alternative, you can request any type of hose to be modified so that it fits NuTone inlets easily. 

Vacuflo inlet doors have always been unique and easy to distinguish from standard inlets.  In the 1950s and 1960s, Vacuflo systems were installed with thinwall metal tubing.  The system turned on when an inlet was opened, thanks to a pair of contacts in the inlet door hinge.  Inlets looked similar to standard “Round Door” inlets, but with a wider “pull tab” at the top:


The 1960s brought several important innovations to Vacuflo systems, including built-in low voltage control relays, lightweight PVC tubing for easier installation, and patented Lexan “Magic Valves”:


These turned the system on when opened, and included a provision for a low-voltage hose to be used (far in advance of the technology in use by competitors at the time).  Exact replacements are still available today, as are the special low-voltage hoses with two pins which make contact with the two holes above the inlet opening.  Alternatively, it is possible to update to standard inlet valves using an adapter plate between the original rough-in frame and the new inlet cover.

One widespread proprietary inlet valve design was used by Sears Kenmore central vacuum systems in the 1960’s and 1970’s, before the company switched to standard tubing, fittings and inlet valves sometime in the ‘80’s.  The first incarnation required the user to press a brass contact strip once to start the system, and again to stop:


Like the original Filtex inlet valves, these required the user to manually start and stop the system, and could allow the motor to run with all the inlets closed.  Once these problems became apparent, Kenmore systems by the mid-1970’s had inlets that turned on when opened, and off when closed:


These simple, reliable inlets remained current until Kenmore transitioned to industry standard 2” OD vacuum tubing and 1.5” ID inlet valves sometime in the 1980’s.

Black & Decker was another innovator in the central vacuum industry, developing their own power units, tubing, fittings and inlet valves starting in the 1960’s.  These systems were marketed by WalVac, Inc.  Inlets were unique in several ways: First, they were installed without a mounting plate, simply friction fitted into the 90 degree elbow, and fastened to the wall with three toggle bolts.  Second, they activated the system with a push button under the inlet hole, which was contacted by a flange on the hose end.  These provided the same effect as modern inlets (turning on upon hose insertion and turning off upon removal), and allowed the use of a non-latching relay.  Original versions were brushed aluminum, and had a unique oblong shape:


Sometime in the 1970’s, Black & Decker began to make the inlets out of plastic, with contact points in the inlet neck like industry standard inlets.  However, these were dimensionally the same as the original style, and thus required a hose just slightly smaller than the industry standard 1.5” in order to fit properly.

For lack of pictures, I have left out at least one rarely-seen style from the 1960’s; that which looked like the early Filtex/CVI push-button inlets, but had a second push button in place of the red light – one to start, one to stop.  I ran across this type of system once, on a “Turbo Vac” installed in Lisle, IL.  While I didn’t think to get a picture of the inlets, I did snap one of the unit:


It’s my hope that this information has been informative and interesting.  I would love to hear from owners of any of the above systems, whether you have a need for service or just would like more info about your system.  Also, if you have a system so unusual you don’t even see it here, it would be especially helpful to me for you to send photos of your system to:

My plans for world domination will not be complete until I have cataloged every known variation of central vacuum inlets known to man!  Buwahahahaha!