Somewhere on your water heater is a reset button. Every electric water heater in America has one. If it trips, water will no longer heat. You need to reset it in order to get hot water again.
If you are familiar with the reset button, have you ever wondered how it works? Have you ever wondered about the mechanics behind it? It turns out the water heater reset button is fairly simple technology. It hasn’t changed much in the last 30 years because it doesn’t have to. It is a very effective device without a lot of room left for improvement.
What It Does
Before getting to the mechanics behind the water heater reset button, a word about what it does is in order. The button is actually a switch. It’s known by other names, including:
- Emergency limit switch
- High-limit safety thermostat
- Emergency cut-off
Regardless of what you call it, its function is to cut off electricity to the heating element inside your tank. This prevents the water from being heated any further. Water heater reset buttons are set to trip at 180°F. The point is to prevent the water from boiling inside the tank, a scenario that would be highly volatile.
The High-Limit Thermostat Circuit
A water heater’s reset button is not a standalone device. Rather, it is one component in a complete high-limit thermostat circuit. The circuit includes a thermometer that constantly monitors water temperature.
The reset switch is connected to the thermometer. If the thermometer reaches the desired threshold, it sends an electrical pulse that trips the reset switch. The reset switch then breaks the connection that normally allows electricity to flow into the heating element.
No electricity means the heating element cannot do its job. The water in the tank gradually cools and any potential danger posed by overheated water is averted.
A Lot Like a Circuit Breaker
It turns out that the reset button is a lot like a circuit breaker. Circuit breakers are designed to withstand only so much current. If current exceeds a breaker’s limit, the excess voltage will break the electrical connection within the breaker. Electricity can no longer flow through.
Like a circuit breaker, a reset switch is reset very easily. You just pushed the button. With a circuit breaker, you move it all the way to the ‘off’ and then back to the ‘on’ position. In both cases, the flow of electricity is restored.
Switch Tripping: Potential Causes
So, what causes a water heater’s reset button to trip? Superior Water & Air, a Utah plumbing contractor that services Washington County and the Salt Lake City area, says the biggest culprits are bad thermostats, faulty heating elements, and worn-out switches.
Superior W&A also says that homeowners should pay close attention if the reset button trips. A single, out-of-the-blue trip that is not repeated probably isn’t something to worry about. As reset switches get older, they can trip for no reason at all. But if a reset button trips regularly, there is something else going on.
When to Call a Plumber
Frequent switch trips are sufficient reason to call a plumber. Homeowners should also look for wet spots under the water heater. They could indicate a potential leak. And if a homeowner smells a burning odor, it is important to cut power to the water heater from the circuit breaker and call a plumber immediately.
Thanks to reset buttons, modern water heaters rarely overheat. The switches cut off electricity when water gets too hot. That makes the reset button a vital safety feature we really can’t do without.