Limit Switches |HVAC Limit Switches
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Limit Switches

About Limit Switches

PlumbersStock offers a variety of options for discount limit switches. We have the best deals on all kinds of HVAC switches. Limit switches are commonly found in furnace applications and it's used as a safety control in your heating and cooling system.

Your heat exchanger is susceptible to cracking from overheating, but the limit switch can prevent this by automatically shutting off the burner. Also, if the gas or oil has not sufficiently heated up the exchanger then the switch won't let the blower activate, for improved management of temperature.

What Is a Limit Switch?

Whenever you have something that works to ignite combustible gas, such as a gas furnace, having an HVAC control in place to shut off the burner seems like a no-brainer. This is exactly what a limit switch does. In addition, a limit switch shuts off the blower when the air temperature has dropped enough after the burner has shut off.

A limit switch is an important piece to have in your gas furnace because it helps your furnace run more efficiently and safely. After the burner turns on, the limit switch has a sensor in the heat exchanger that tells it when the surrounding air is warm enough to circulate. When this sensor determines the air temperature is high enough, the limit switch turns on the blower and allows warm air to exit to the home. Once the air temperature falls, the switch turns the blower off. Without a properly working limit switch, you wouldn’t be able to properly circulate warm air into your home from your gas furnace. Since the limit switch also acts as a failsafe to shut off the burner when the air in the system exceeds the maximum temperature, you may run into some serious accidents if the limit switch is faulty.

Troubleshooting Your Limit Switch

Since your limit switch acts as a safety device that monitors the air temperature inside your furnace and shuts down the gas valve to the burner as needed, it plays an essential role in keeping your furnace from overheating and possibly causing damage. If you suspect your limit switch is faulty, don’t wait until something regrettable happens—test it out for yourself and replace it if necessary.

Troubleshooting your limit switch isn’t a difficult task but will require a few tools and an hour of your day. Your limit switch may become damaged over time if you encounter frequent tripping due to overheating and a low airflow from a clogged air filter. A dirty air filter allows heat buildup which will cause the switch to cycle on and off or “trip” frequently. If this cycle continues, your switch will eventually fail or get stuck in the on or off position permanently. To test and see if your limit switch is the problem, you’ll want to use a multimeter and check for continuity.

To do this, set the multimeter to Ohms (resistance). Disconnect the wires from each terminal. Place a probe on each of the switch terminals on the switch’s faceplate (you’ll find these terminals located outside the furnace). If the resistance reads 0 Ohms your switch is fine. If the resistance is infinite, your switch is bad and will need to be replaced.

Buy HVAC Limit Switches Online

With all the limit switches we offer, it can be tricky knowing which one to purchase for your furnace. If you need assistance, please contact our friendly and knowledgeable customer service staff and let us help you find what you’re looking for. See for yourself why professionals and homeowners alike trust PlumbersStock for all their HVAC, plumbing, and tool needs. Save on the best HVAC parts from the most trusted brands in the business, including Frigidaire, Partner's Choice, ADP, and more.

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