PSC vs ECM Blower: What’s the Difference?

Heating, ventilation and cooling (HVAC) systems require a blower. Whether you’re warming or cooling your home, the blower will move the conditioned air into your HVAC system’s ductwork. Blowers consist of a motor that’s attached to a fan. The motor will spin the fan’s blades while subsequently circulating air.

While they are all designed to move the conditioned air into the HVAC, there are different types of blowers. Most blowers can be classified as permanent split capacitor (PSC) or electronically communicated motor (ECM). What’s the difference between PSC and ECM blowers?

What Is a PSC Blower?

A PSC blower is a simple type of blower that can turn on and off. PSC blowers will turn on in response to the thermostat. If your HVAC system has a PSC blower and you set the thermostat to heating or cooling – or if you set the fan to “ON” -- the PSC blower will turn. It will continue to run until the desired temperature has been reached, at which point the PSC blower will turn off.

In the past, most HVAC systems had a PSC blower. PSC blowers are still around, but many new HVAC systems now feature an ECM blower. PSC blowers have been around for a longer length of time. ECM is a newer type of blower that’s becoming more popular.

What Is an ECM Blower?

An ECM blower is a type of blower that can operate at different speeds. ECM blowers can still turn on and off, but they support variable speeds.

ECM blowers don’t run at full speed all the time. Instead, they’ll typically start at a slow speed and gradually increase their speed.  The speed at which an ECM blower operates is determined by a controller. The controller will tell the ECM blower when to increase its speed and when to decrease its speed.

Choosing Between a PSC and ECM Blower

The main difference between PSC and ECM blowers is that the former can only turn on and off. ECM blowers, on the other hand, can operate at different speeds.

ECM blowers are also more energy efficient than PSC blowers. Some reports suggest that ECM blowers are over 50% more energy efficient than their PSC counterparts. PSC blowers run at full speed all the time, so they consume more energy.

ECM blowers are better protected from wear and tear than PSC blowers. By running at a slower speed, they are exposed to less mechanical friction. The result is a longer lifespan for ECM blowers.