Earlier we discussed how motor specifications printed in the brochures are very misleading. Furthermore, central vacuum motors are hidden inside the central vacuum unit so the consumer generally has no idea what it is they are actually paying for.

We strongly suggest that you ask about, and if possible, see what motor is being used inside the central vacuum you are about to purchase. If they don't want to show you then maybe there is a reason. Seeing the motor and comparing it to what you learn from this page will give you a very good indication of the quality of the system.

There are many central vacuum choices available and the quality and longevity of each motor depends on the motor.

To start, let's first discuss the anatomy of your central vacuum motor.

Inside your central vacuum, is a high performance motor running at speeds of 20,000 - 35,000 RPM's to achieve very high performance. Not all motors are created equal however so buyer beware.

The anatomy of a central vacuum [Figure 1] consists of several parts which you may hear referred to in a sales presentation.

These include - see [Figure 1]:
(1) Motor Carbon Brushes
(2) The Armature
(3) The Field
(4) The Fans, which when stacked together create what is referred to as "Stages". A one stage motor for example would have one fan, a two stage motor would have two fans, a three stage motor would have three fans.

Central vacuum manufacturer's have a virtual buffet of motor choices available to choose and from several motor manufacturers.

 Ametek/Lamb, Domel and Electro-Motor all manufacture a wide variety of central vacuum motors and just as there are a wide variety of motor choices, so are there performance specifications.

Knowing what to look for in a central vacuum motor will be the difference between a wise investment and, depnding on what you paid, a bad investment.  It is generally accepted that Tangential Bypass motors are the best choice for central vacuum applications simply because all heated discharge air is exhausted and dedicated clean air cools the motor. In addition, choosing a motor with an aluminum chassis, while more expensive, will last longer and is more reliable in our experience [Figure 2].

There are three basic styles of motors that are commonly used in the manufacture of central vacuum systems these are: The Flow-Thru motor, Periperhal Bypass and Tangential Bypass motor.

[Figure 1]

[Figure 2]

The Flow-Thru Motor (Average)

This is a type of motor most commonly found in less expensive central vacuum systems or some canister or upright vacuum cleaners. However, choosing a central vacuum with a high retail price does not ensure you will not find this motor being used so buyer beware!

Most often, these motors are generally used in conventional canister vacuums or upright vacuum cleaners. They are very affordable and indeed offer excellent performance (some over 700 Airwatts) for a low price.

Since this type of motor does not have a dedicated cooling fan, it uses filtered vacuum air to cool the motor which means any particles which pass the protective filtration will be used to cool the internal mechanics of the motor reducing its life.

In addition, the absence of a tangential bypass found on premium motors means that exhaust is being vented inside the motor chamber adding heat and whatever dirt particles may have past through the filtration.

Typically these motors do not last as long because they use vacuumed air to cool the motor then vent the heated exhaust air into the motor chamber. Furthermore it is critical to ensure that vacuum air is available to cool these motors because they are not equipped with a dedicated cooling fan.

The Peripheral By-Pass Motor (Good)

Again typically less expensive then a tangential type motor, these motors actually employ a cooling fan on top of the motor which blows fresh clean air over the armature and exhausts it peripherally through small vents around the side of the motor.

Generally more powerful then their Flow-thru cousins these motors are more reliable since clean fresh air is being used to cool the armature.

However, since these motors are not equipped with a tangential motor exhaust, heated dirty exhaust air is vented into and around the motor chamber which contributes to a lower life expectancy.

As with the Flow-Thru motors, you will sometimes find these motors used in a dual motor unit to boost performance specifications.

The Tangential By-Pass Motor (Better and Best)

Bar far the best, this style is the most commonly used motor in the central vacuum industry with the 5.7" diameter sizes generally being the most widely used and larger motors reserved for higher end premium central vacuums.

Cana-Vac is one of few manufacturers which offer the largest performance motors in the industry 8.4" Diameter! Built to last, designed to perform.

Tangential motors, while more expensive then the other two motor types, the implementation of a tangential exhaust ensures all heated and dirty exhaust is removed completely from the motor chamber and expelled thus maximizing motor life. 

Since all heated and dirty exhaust air is exhausted tangentially, a central vacuum of this type fitted with an outdoor exhaust ensures that 100% of allergens and pollutants are exhausted out of your home. No canister or upright vacuum can make that claim no matter how fancy their filtration!

When looking at these motors, pay attention to the chassis which can be either plastic or aluminum [Figure 2], with aluminum being much more durable.

There are several sizes of tangential motors 5.7" diameter, 6.6" diameter, 7.2" diameter and the titan of them all the impressive Ametek/Lamb 8.4" diameter motors which use Infinity™ brush technology.

Tangetial bypass motors are the best suited for central vacuum applications.

When shopping for your central vacuum, be sure to ask what is the motor size? Is it a Flow-Through, Periperheral bypass or Tangential bypass? Best of all ask to see the motor! If they don't want to show you why not?

Be Informed
Ask What's Inside!