Even though there are different types of vacuum motors, there are also various motor sizes. At the lower end of the spectrum, Thru-Flow motors range in size from 4.7 to 5.7 inches in fan diameter. On the other end of the variety, you can get a premium Tangential Bypass motor in fan sizes up to 8.4 inches in diameter similar to that found in a Cana-Vac model XLS-970.

When shopping for a central vacuum and comparing retail costs, it would be best to take special note of what type of motor it has (a Thru-Flow or Tangential Bypass) and the fan's diameter. This will help you in comparing the true value since larger motors cost more.

Larger motors are intended for the heavier workload of larger homes where a central vacuum system is used for more extended periods. For instance, a 12 thousand square foot home would need more vacuuming for more hours than a 2 thousand square foot home. They are built to be more robust with a host of engineered characteristics that set them apart from smaller motors. 

Motor Anatomy

This section provides a more detailed analysis of the anatomy of vacuum motors. This information will help you become familiarized with terms you may encounter when comparing central vacuum systems. It is worth noting that only the Tangential Bypass has a Motor Cooling Fan.

Both motors have the following elements in common:

1. Motor Carbon Brushes

2. Field laminations and Armature

3. Fans – the number of fans stacked equals Stages. A two-stage motor has two fans, while a three-stage has three fans.

The Peripheral-Bypass Motor

In addition to the Thru-Flow and Tangential Bypass motors, there is a third motor type we have not addressed since it is not commonly used. This is the Peripheral Bypass motor.

Peripheral Bypass motors share the same advantages as Tangential Bypass motors. They both have a dedicated cooling system separate from vacuumed air. That means both should have a longer life expectancy.

The difference between the two is how they dissipate vacuumed air. The Tangential Bypass has a horn that attaches to PVC plumbing and a muffler to vent away from the motor. The Peripheral Bypass motor ejects exhaust air around the motor.

Most experts recommend the use of a Tangential Bypass motor. It is the preferred and most popular choice because heated exhaust air is removed from the motor chamber and vents contaminated exhaust air away from your living environment.

References and Resources

• Comparing central vacuum systems
• Using of a Tangential Bypass motor