What Heat Pump Capacitors Are & What They Do

While it’s not something that most homeowners think about, a heat pump capacitor plays an important role in ensuring that your heat pump powers on and operates smoothly. So, a capacitor is essential to making your home comfortable.

In this guide, the experts at National Heating and Air Conditioning will break down what heat pump capacitors are, how they work, and how to tell if they’re starting to struggle.

What Is a Heat Pump Capacitor?

Often described as the “starter” for the unit, a heat pump capacitor is a small part of the outdoor unit that delivers energy so that the motor can kick on.

Since a heat pump is a dual system (that can cool or warm a house), when the thermostat calls for a cooling or heating cycle, the capacitor provides the power needed to start the motor that drives the entire system. Without it, the motor wouldn’t start, and the heat pump would stay inactive.

In short, a heat pump capacitor acts like a battery — storing electrical energy and then quickly releasing it when needed. This jolt is what allows the heat pump to start, and it keeps the motor running smoothly throughout each heating or cooling cycle.

How They Work

As mentioned, the capacitor works by storing energy and then releasing that energy at the right time. The right time is when the thermostat detects a need for heating or cooling, which triggers the heat pump. This trigger sends an electrical jolt to the motor, and that starts the entire system — in turn, starting the heating or cooling process within your home.

Two Types of Heat Pump Capacitors

The two main types of capacitors used in heat pumps are start and run capacitors. Each type has a unique purpose, and — depending on the model — a heat pump might have both types or just a run capacitor. Here’s a little more info about each one:

Start Capacitor

As you might tell from the name, the start capacitor provides the initial energy needed to turn on a heat pump. This capacitor type provides a high-energy burst at the start of the cycle, which helps the motor get moving. So, once the heat pump is running, the start capacitor’s job is finished, and it stops.

Run Capacitor

Unlike a start capacitor, a run capacitor remains active throughout the entire heating or cooling cycle. It provides a steady, low level of energy that keeps the motor running smoothly. This ensures that the motor receives consistent power, making the operation more efficient and the system strain less.

5 Signs of a Failing Capacitor

Just like most HVAC parts, a capacitor, unfortunately, doesn’t last forever. It will inevitably wear out or fail — subsequently impacting your heat pump’s performance and your indoor comfort.

Yet, there are some warning signs you can keep an eye out for to see whether your heat pump capacitor is on the fritz:

• Difficult starting up: Because the capacitor is responsible for providing the energy that starts the heat pump motor, if your heat pump is struggling to start, then the capacitor is likely the culprit.
• Frequent cycling on and off: If your heat pump is also cycling more frequently, then the capacitor might not be providing enough power to keep the system running efficiently.
• Humming noises: If the outdoor heat pump unit’s capacitor is struggling to deliver power to the motor, you might notice a faint humming sound.
• Higher energy bills: Finally, an inefficient capacitor will cause your heat pump to work harder than necessary, leading to increased energy usage and higher utility bills.

If you notice any of these problems, don’t hesitate to have an HVAC professional inspect and repair your heat pump unit. Even though a capacitor is a small part of the system, it’s essential for a heat pump to work correctly, so fixing it requires a trained technician.

24/7 Heat Pump Repairs in Cincinnati

If you’re in the Greater Cincinnati area and need heat pump services, let National Heating and Air Conditioning help. For over 90 years, we’ve been the Cincinnati region’s go-to crew for HVAC services.

Learn more about our process or request a quote by call us or contacting us online today.