Thursday, December 16, 2010

Vintage Commercial Filtex

Here's a very unusual unit, especially for a residence -- a Filtex model CTS-500, installed in the mid-1970's when this Oak Brook, IL home was being built. This unit was originally offered as a commercial system, due to its long-life, slower-running 7.5" motors. How it found its way into this house, it's hard to say. The subdivision has quite a few homes with Filtex systems, mostly TC-600L units like this one below:


The TC-600 uses 7.2" motors, draws slightly higher amps and creates noticeably greater end-of-hose cleaning power. Both systems displace a maximum of about 230 CFM, but the TC-600's higher waterlift (110" vs. 88") enables it to better overcome the resistance of a 30 foot hose plus the piping system.

It is interesting to note that this CTS-500 was set on the floor, instead of being wall-mounted like most central vacuum units (including nearly all of the old Filtex systems that I have seen). Filtex units are one of the very few systems that could actually sit on the floor, owing to their externally-mounted motors and flat-bottomed canister.

This homeowner was in love with the system, and decided to replace the worn-out motors instead of opting for an entirely new power unit. I can't say I disagree -- what other system today has a 16-gallon bag capacity, and motors that can run for 2000 hours? This system will be working long after most of the neighbors' central vacuums have died. "They just don't make 'em like they used to."

Tuesday, December 7, 2010

Wyes vs Tees

When I supply do-it-yourselfers with fittings and tubing to install a central vacuum system, often I am asked why I only supply 45 degree "wye" fittings instead of the much more common 90 degree "tee" fittings. The main reason is, everything you can do with a tee, you can also do with a wye. In fact, you can make a wye into a tee just by adding a street 45 elbow. However, there are lots of things that you can do with a wye that just cannot be done nearly as well with a tee. Like this example I found during a service call in Winfield, IL recently...

We have here a main trunk line that converges to the power unit mounted on the basement wall below. Arranged with a wye fitting, dirt from either side only has to make a 90 degree turn. The original setup (which I am holding up for the photo) using a tee forced dirt coming from the right to go through three 90 degree elbows, or 270 degrees in total.

I rest my case.

Tuesday, November 30, 2010

Visiting a home in Naperville to replace a relay in their older NuTone central vacuum, I came upon this:

Somebody (basement contractor?) had used 1.5" DWV plumbing pipe to extend this central vacuum line. This creates a ridge at the transition which can catch debris -- a major "Bozo no-no" and an invitation for clogs. I corrected that for the homeowner, as well as this little gem:

The power unit in this case is to the right. The tee on the left, while pointed in the correct direction, is what's known as a "drop-out tee" -- that is, dirt traveling horizontally will fall into the branch line, instead of making it all the way back to the unit. The tee on the right doesn't have this problem, but it is pointed in the wrong direction, forcing the dirt to make an almost-U-turn; another invitation for clogs. Fortunately, the fact that whoever did this used foil tape instead of PVC glue made it rather easy to take apart and re-do properly. This system now works better than it ever has.

Friday, November 5, 2010

I was called out to unclog a central vacuum system in Wheaton, IL recently. My standard procedure is to use a special dual-motor, high waterlift unclogging unit, suctioning the clog out from the inlet. This works very well, and I was getting good results this time -- removing lots of lint and hair from the inlet that wasn't working. An important step in removing a clog is to, after suction is restored, vacuum a full paper towel sheet through the system. If the clog is completely gone, the paper towel will make it all the way to the unit in a few seconds. Oftentimes a clog is caused by a long object like a pencil, which catches lint and debris. The paper towel ensures that the item which started the clog has been removed. In this instance, I was unable to get the paper towel to go completely through the pipes. Even after trying several times, the paper towel seemed to be catching in the same spot. The lines to the second-floor inlets in this home were run up to an attic trunk line, which then went down to the basement. One technique to use, with a clog that is difficult to remove, is to walk around and listen for a "whistling" or "hissing" sound in the pipes -- often this will indicate where the clog is, and allow you to cut the pipe and inspect. In this case, I was hearing a noise in a hallway wall which backed up to a bathroom. Inside the bathroom, I could hear the noise most clearly at the point where a toilet paper roll holder had been attached to the wall. In fact, the noise would change if I moved the holder.

Removing the left side of the holder (which was attached to the wall with a toggle bolt), I found this:

I turned the system on again and there was airflow through the hole. Just as I thought -- the hole for the toggle bolt had been drilled directly through the center of the vacuum line going down to the basement. The next step was to cut away a section of drywall which would allow me to repair the pipe.

This allowed me to further inspect the pipe. Since this was a cleanly drilled hole and went through only one side of the pipe, I was able to repair it without cutting out the damaged section of pipe. I took a slip coupling, cutting a 1" section out of it so that it could be "clipped" over the pipe, after first being coated with PVC cement. The finished repair is below...

Amazingly, this house (along with the vacuum system and the toilet paper roll holder) was ten years old -- even with a toggle bolt obstructing the pipe serving all the upstairs inlets, the system took ten years to clog. The homeowner was left with a system that worked better than it ever had, and only a 2 1/2" square of drywall to fix. Of course, I also made sure she knew not to mount that holder in the same spot.

Thursday, October 14, 2010

Cyclonic Separation

Central vacuum systems which rely on momentum to separate dirt from air are known as “fully cyclonic” or “true cyclonic” systems. They are advertised as “filterless”, which is only partially true – all have a coarse mesh screen to protect the motor from lightweight debris which can get past the cyclonic separation and would otherwise be sucked into the fan blades. The two most common fully cyclonic systems are made by Vacu-Maid and Vacuflo. Both have been manufacturing systems for decades, and both produce high-performance, well-made systems. However, I believe the Vacuflo to be a superior system due to the design of the cyclone separator.

This is a diagram of the Vacuflo system. The screen is located at the bottom of the “top hat” above the cone. Dirty air enters tangentially at the top of the chamber, and swirls downward around the “top hat”. Air and dirt are compressed as they reach the flange at the bottom of the “top hat” (in a design patented by the inventor of the Vacuflo system in the 1950’s), and the air turns and enters the screen. The momentum of the debris causes it to continue downward around the inside of the cone, until it reaches the bottom and drops into the bucket. The Vacuflo system is close to the design of a “theoretical cyclone” and achieves a 96 to 98 percent separation efficiency. Motors in these units are known to last for decades, and buildup of dust on the fan blades is minimal.

Here is a diagram showing how the two types of Vacu-Maid systems (single piece and split canister) work. Notice how, on both types, air and dirt enter and make an immediate sharp 90 degree turn. Not only is this type of intake much less smooth for the airflow than a tangential intake, the sharp 90 elbow is prone to clog with debris that has made it through the rest of the piping system. On the single piece unit, the intake elbow is placed near the bottom of the separation chamber – causing the air (and quite a bit of the dust) to be drawn upward to the screen. The screen on a Vacu-Maid gets dirty more quickly than the screen on a Vacuflo for this reason, and yet is more difficult to clean, being located higher up in the canister (inside the upper cone, just below the motor). It is very hard to completely clean this screen. Vacu-Maid’s answer to this problem was the split canister system. In this type, the intake elbow is located near the top of the chamber, which is an improvement. Dirt and air swirl around the standpipe in the middle of the canister, until reaching the flange attached to the bottom of the standpipe. This is more similar to Vacuflo’s design, but carries a major disadvantage in that the 2” diameter pipe has much higher velocity air flowing through it than the 7” diameter screen on a Vacuflo unit. This causes debris to be sucked through the standpipe more readily than it would be if the surface area were larger. Air and debris that enters the standpipe goes up to the top and makes a U-turn to enter the screen from above. While this makes the screen much easier to clean (just lift the lid off the top of the unit), it causes objects that would normally drop off the screen when the system is shut off to remain there until the screen is manually cleaned. Things like tissues, Styrofoam peanuts, lint, etc. build up quite readily on the screen of a split canister Vacu-Maid system, which is why the owner’s manual cautions against vacuuming such items up. If picked up by a Vacuflo system, those objects would cling to the screen until the system was turned off, and at that point would drop off the screen into the bucket. The Vacu-Maid separation design achieves only about 90 percent efficiency, and lets much more lint and dust through the motor’s fans. For this reason, a ten year-old Vacu-Maid system is quite a bit noisier than a brand new one, and the only way to remedy the situation is to replace the motor. I have video clips (which I will post) of a Vacu-Maid S3200 running and a Vacuflo 960 running. These systems have the same exact motors, and had a similar amount of usage on them (verified by checking motor brush length). The difference in sound level is dramatic. Were the cyclonic separation of the Vacu-Maid as efficient as that of the Vacuflo, the motors would run just as smoothly even after years of use.

Friday, October 8, 2010

This homeowner had an existing Vacu-Maid system, about ten years old, in their large Oak Brook, IL residence. I was here to remove a clog and commented on how much quieter the outside exhaust would be with mufflers in the exhaust lines. This resulted in a return visit to install the mufflers and move the unit a few feet down the garage wall. Check out how much nicer the installation looks now:


The home originally had an old Filtex system (original brass inlets still in place), which at some point had been replaced with a Vacu-Maid P325 (you can faintly see the outlines of the brackets for the old unit). Heavy use caused that system to need replacement, which is when this one, a Vacu-Maid S3200 was installed. Very powerful, but noisy and the cyclonic separation in these units is inferior. I'll elaborate exactly what I mean in a later post...

Sunday, October 3, 2010

I ran across this in a service call the other day. The pipe coming from the lower left of the picture is a main line, which picks up a basement inlet then makes a right turn and continues on to the unit. Not only does the tee drop out of the main line at a 45 degree angle (filling the basement inlet with dirt), the pipe from the basement inlet makes a U-turn, forcing the air (and dirt) to do the same thing.

Here's the after shot. Not only is it better for the airflow, it avoids dirt from the main line ending up sitting in the basement inlet (and it took one less fitting than the prior arrangement to install).

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