Central Vacs

There are three reasons to consider a central vac for your next building project: superior cleaning power, ease of use and quiet operation inside your home.

By Steve Maxwell

A central vacuum is one of those household features that adds way more value to a home than the trouble and expense of putting it in. And installation is easy, if you tackle the job at the early stages of the building process and with the right knowledge. Necessary know-how is what you’ll get here. If you can cut and fit plastic plumbing drainpipe and make basic, low-voltage wire connections, then your central vac installation will be a breeze.

There are three reasons to consider a central vac for your next building project: superior cleaning power, ease of use and quiet operation inside your home. No hand-pushed vacuum can compare with the performance of even an ordinary central system. With recent advancements in central vacuums themselves, performance is cleaner and quieter, with filter maintenance easier than ever.

All central vac systems have three main parts. The first is a network of thin-wall, two-inch diameter PVC piping that delivers vacuum suction to flap-door outlets around the house. Technically it doesn’t really matter what kind of pipe you use, as long as it’s large enough in diameter. But stick with proper PVC vacuum pipe just the same. It’s cheap, easy to work with and sized to accept all the various outlets that connect with the flexible floor hose and attachments you’ll use while cleaning your house.

The second part of any central vac system is a network of wires running alongside the vacuum pipes installed within wall and floor frames. You may want one or two separate wiring networks, depending on the kind of central vac equipment you plan to run.

At a minimum, all central vacs have at least one pair of low-voltage wires that switch the vacuum unit on automatically whenever a hose is plugged into an outlet. These wires typically carry harmless DC power to a relay in the vacuum unit. The other ends of the wires connect to electrical lugs on the back of each flap-door fitting. Whenever you plug the metal end of the corrugated vacuum cleaning hose into the flap door, it touches two internal metal contacts, completing a circuit that switches the vac on. The electricity to power the vacuum isn’t actually carried by these low-voltage wires; they only switch a relay that in turn energizes the vacuum by switching on regular household current.

Will you have lots of wall-to-wall broadloom in your new home or addition? You should consider a second network of wires that deliver 120 volts of power to an ordinary duplex outlet positioned right next to each central vac flap door. This allows the use of electrically powered carpet heads on the end of your vacuum cleaning wands. Just plug in the 120-volt power cord that comes out of the vacuum hose whenever you connect your vacuum hose to the wall, and the electricity drives a rotating ‘beater brush’ on the carpet attachment, boosting broadloom cleaning action substantially. If you have mainly hard-surface floors, you can save time and money and forget the 120-volt wiring. Some carpet cleaning heads can operate without electricity (they’re powered by the flow of air into the system) so the 120-volt circuit isn’t completely necessary.

The third part of your central vac system is the vacuum itself, and this is where interesting new hardware has recently hit the market. For more information on the kinds of technical features you need to look for in leading-edge central vacs, take a look at Clean, Quiet and Leading-Edge on right.

Pipes and Wires
The main work of installing a central vac involves weaving pipes and wires through wall and floor frames. The PVC vac pipe you’ll be using cuts like a dream on any chopsaw, though a good hacksaw works just fine for occasional cuts. Either way, remove burrs on the inside and outside of the pipe after each cut.

Completing joints is easy. Just swab some PVC cement on the outside of the pipe and on the inside of fittings, then push and twist the parts as they go together. In a couple of seconds the joint will be locked vacuum-tight as the cement sets. Low voltage wires simply run alongside the pipe, ty-wrapped in place every 18 inches.

But before you get this far, you need to do some planning. Where should the vacuum pipes go? How far between outlets? Where will the vacuum itself be located?

Begin answering these fundamentals using a piece of rope that’s 30-feet long. That’s the same length as a standard central vac floor hose. Identify potential outlet sites on your floor plan, and then test them with your rope. Can you get to every spot in your house? Would one specific combination of outlets reduce the total number of outlets required? How does internal wall and floor framing affect your ability to actually install outlets where they’d work best? Take your time here, since good planning saves lots of effort.

When it comes to installing your rigid vac pipes, the main thing to understand is the need to create only gentle bends, and even then, as few of them as possible. Abrupt, 90-degree elbows sap vacuum power by boosting internal air friction. They’re also more likely to get plugged with debris. That’s why vacuum pipe manufacturers offer large-sweep 90-degree elbows. Use them whenever you can. These have a greater radius than conventional elbows and that makes all the difference. If you can’t find large-sweep elbows where you live, use two 45-degree elbows joined together to create a gentle 90-degree turn. They’re almost as good.

When you get around to running lengths of vac pipe, there are a couple of ways you can anchor it. One of the best uses U-shaped, PVC straps made especially for the job. Just screw them in place to underlying wood. In situations where vac pipe needs to be suspended below or beside wooden framing members, perforated metal strapping is a great alternative. Just unroll what you need and cut it off with some metal tin snips. Have both U-shaped straps and metal strapping on hand before you get going with your installation. You’ll probably need both. And as you work, just remember to go easy on the pipe. It needn’t be fastened with a lot of pressure. As long as it doesn’t flop around, you’re fine.

Wiring 120-volt duplex outlets next to vacuum flap doors for powered carpet heads is exactly the same process as wiring any other outlet. But the low-voltage wiring that switches the vacuum on and off is different. Since the voltage involved here poses no safety hazard, standards are relaxed. There’s no need for code-approved electrical boxes and fancy insulation. Simply run some flexible 18/2 or 16/2 lamp cord from each end of a vacuum pipe branch line back to the location where the central vacuum unit will go. I use plastic ty-wraps to secure this wire to the pipe every 12 to 18 inches, leaving a foot of extra wire at the ends. But since the integrity of low-voltage wire connections is so important, leave as many of them accessible as possible. Also, for an added measure of reliability, solder all low voltage connections, and then twist on a Mar-type wire nut over top. It takes just a few minutes and might someday save you the hassle of cutting into a wall cavity to repair a broken connection.

Central vacs cost a bit more time and money up front, but the value delivered makes this homebuilding option a no-brainer. Install today’s best hardware in the best way and you’ll never have regrets.