a red reset button being tested with a voltage meter

Limit Switch

Originally contributed by • last updated 3/16/2021

American Water Heater
American Water Heater

When dealing with modern day electrical appliances, there are very few things that could cause them to damage your home’s electrical system. That’s because these days, many household appliances, such as furnaces and hot water heaters, come equipped with standard safety features, such as limit switches. These safety features are designed to prevent serious damage in case they malfunction or break.


The term limit switch most commonly refers to a device or a sensor that is designed to limit or stop the performance (or over-performance) of an appliance or a machine. When triggered, one of these switches will prevent or limit further operation, typically as a safety measure. Around the home, these handy little safety features are usually found in hot water heater thermostats or as furnace high limit switches. For the most part, they act similar to a circuit breaker switch inside your breaker box. Outside of typical household uses, limit switches have many designs and applications.

What’s The Easiest Way To Reset A Limit Switch?

High limit switches on hot water heaters and furnaces are designed to trip if the temperature gets too hot. Oftentimes, if this happens, these handy little safety features will need to be reset. Most of these safety switches are fairly easy to locate and reset, especially on hot water heaters. And, it’s rare that you’ll ever need to replace one.

  • Resetting the limit switch on most hot water heaters is fairly easy. Typically, it is a big red button on the upper thermostat of the hot water heater unit. You’ll probably need to access it by removing the plastic cover. Push the button to reset the switch.
  • On most furnaces, the reset button is typically located inside the access panel. Quite often, it is a red button. Remove the access panel from the front of the furnace and hold it down to reset the limit switch.
  • Other devices and appliances may also come with limit switches, such as garbage disposals and dishwashers. In most cases, the reset buttons are fairly easy to identify as they are typically red (or black).