What are furnace capacitors and why your team needs special training on them.

Furnace capacitors are just one component in the furnaces that your HVAC technicians regularly work on. This popular component is something your technicians will come across regularly.

Training on furnace capacitors is essential, just like training on any other HVAC component. After all, your technicians must be familiar with and comfortable working on all the parts of an HVAC system. Proper training allows you to deliver high-quality service and get satisfied customers consistently.

With furnace capacitors, there are additional safety considerations associated with training because of the high temperatures and electricity involved.

What is a furnace capacitor?

A capacitor is a passive device that stores an electrical charge on a set of plates when you connect it with a voltage source. This definition is true in any type of capacitor, including furnace capacitors. The name comes from the fact that capacitors have the “capacity” for storing energy. Because capacitors store energy, they are commonly compared to a battery.  

The symbol for a capacitor is as follows:

electrical symbol for a capacitor

Basic design and understanding of the science behind capacitors.

The most basic construction of a capacitor features at least two parallel metal plates that might be circular, square, rectangular, spherical, or cylindrical. They must be metal, as this material conducts electricity. It is essential that the plates are parallel and do not touch. A good insulator (like mica, ceramic, plastic, or waxed paper), liquid gel, or air separates them and is known as the dielectric. Engineers choose the dielectric used in a capacitor-based on its application, as some do best with high-voltage or high-frequency applications.

The insulator makes it impossible for DC currents to move through a capacitor. Instead, the voltage stays on the plates, creating an electrical charge.

The following image helps you visualize how this works.

diagram to understand how capacitors work

Applying that knowledge to furnace capacitors

The above information applies to all capacitors. There are multiple types of capacitors in most furnace systems. One is the start capacitor, a component that gets the motor started when someone turns the heater on.

The other type is the run capacitor, which most people refer to as a furnace capacitor. A run capacitor is found in air conditioning and HVAC systems, as well as furnaces. This capacitor is responsible for giving the fan motors in the system electricity. Those fan motors then use that electricity to let the blowers shift hot air in the system, heating the space.

To put that in perspective, consider the following image of a condensing furnace.

schematic of a condesing furnace

Major trends influencing furnace capacitors – the dangers and required special training.

The danger associated with handling a furnace capacitor is a big reason that your technicians must have sufficient training. The electrical charge that the capacitor stores poses a risk of electrical shock. Additionally, the unit’s oil can be hazardous, and various components can be burning to the touch.

Discharge the furnace capacitor

There are specific steps to working with or discharging a capacitor, whether it is a furnace capacitor or an air conditioning capacitor. Your technicians must understand how to discharge the capacitor, as this is necessary before working on the AC or furnace’s internal components. Remember, due to the capacitor’s design to store energy, one can not merely unplug the furnace/capacitor and call it good. 

Your technicians should start by turning off the circuit breaker with the connection to the furnace.  They should then use a circuit tester (a non-contact one) to confirm there is no power to the device. They can then use a screwdriver to open the furnace and access the furnace capacitor.

As your technicians work on the inside of the furnace, they should take care not to touch anything. There is a risk of electric shocks from exposed wires and connectors. They should then hold a screwdriver, being careful only to touch the handle. That part is insulated and protects you from shocks.

The technician carefully puts the metal part of the screwdriver on the capacitor’s two protruding terminals. This process shorts the circuit, causing it to release any stored electrical energy.

After discharging the capacitor, it is safe to work on the furnace. Your technician’s training will also reinforce that some furnaces have several capacitors, and they must discharge all of them.

Other topics your technicians must understand

Ideally, your technicians will have thorough training regarding furnace capacitors. This training should include dozens of topics, but some of the essential concepts include:

  •   Ohm’s Law (Watts or power = voltage x current)
  •   Expect inductive motors in compressors and motors from HVAC systems
  •   The ideal capacitor size will cancel out any phase shifting of the inductive motor
  •   Most air conditioning systems have dual capacitors

The individual pieces of furnace capacitors – how long do they last and questions for technicians to ask.

On average, capacitors last about 20 years. That being said, numerous factors can reduce their life span. You should teach your technicians to ask customers specific questions to determine if the capacitor may be nearing the end of its life span. The life span can also be significantly less for a furnace capacitor that is too small for the furnace or contains poor construction.

By taking the time to ask customers these questions, your technicians seem considerate to customers as they deliver a high level of customer service, thus improving your customer retention rate.

How hot is the area by the furnace?

Unfortunately, capacitors, including furnace capacitors, can have a reduced life span if exposed to high temperatures for long periods of time. This problem is likely to be an issue with furnace capacitors due to the nature of the furnace. Your technicians should gauge the extent of the heat by talking to customers and examining the area.

What voltage rating does your capacitor have?

If someone who may be unqualified replaced the furnace capacitor last, your technicians should ask customers if they know its voltage rating. Using an undersized capacitor reduces its life span, so this is important to keep in mind.

Have you noticed anything unusual about how your furnace functions?

Your technicians should always ask customers if they noticed anything odd about how their furnace is functioning or any warning signs. Issues may indicate a problem with the capacitor or a problem with another component that requires attention.

Some indications of problems with the capacitors include:

  • Humming sounds when the fans should turn on
  • The furnace turns on, but fans do not make noise and, no air goes through its vents
  • Clicking sounds when the furnace starts up
  • A burning, acrid smell from the vents
  • The motor is erratic

Your technicians can then keep this information in mind as they test the capacitor.

Training on furnace capacitors vs. no training.

To drive home the point that your technicians should have special training on furnace capacitors, consider the difference that this training makes in several key areas.

Safety: Without proper training, working on capacitors can be dangerous due to their electrical charge. There is a serious risk of electrical shocks if your technicians do not know how to discharge or work with furnace capacitors properly.

Attracting Customers: Working on furnace capacitors will help your HVAC business attract more customers, as you will offer more services.

Customer Retention: You will do a better job of retaining customers when your team has proper training. Then, they will have the ability to safely, accurately, and efficiently fix the issue. Your customers will appreciate the efficient service, as that reduces downtime and labor costs. customers will also just appreciate the fact that your technicians resolve their issues and get their furnace working properly again.

Conclusion: why your team needs training on furnace capacitors.

Furnace capacitors store the charge used to start and run the motors and fans that let a furnace work. Ensuring your technicians have thorough training on furnace capacitors keeps them safe, lets you attract customers and leads to increased customer satisfaction.

Even when trained technicians are that you trust to complete their jobs, you need a way to communicate with them in the field to share progress, questions, or concerns. Podium’s Teamchat can make communication among your team a breeze. Your company can also benefit from other Podium features, such as Reviews to help you build your reputation through customer reviews or Webchat to communicate with potential customers who visit your website. You can even try most of these features for free with Podium Starter.

Jennifer Wilson
Jennifer Wilson Strategic Home Services Account Executive

Jennifer Wilson is a home services professional at Podium, the premiere messaging platform that connects local businesses with their customers.

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