To keep water at a consistently comfortable temperature, you'll rely on a working water heater thermostat. These thermostats control not the temperature of the heating elements, but for how long the element is on. They control the water temperature in this way. While gas water heater thermostat's were popular in the past, the vast majority are now electrical. Whirlpool is a popular manufacturer of water heaters, sold exclusively at Lowe's.
There are two parts to a water heater thermostat. The bottom half is responsible for temperature setting, while the top half is the controller. Once the water is over a certain temperature set by you, the top half of the thermostat turns off the bottom half. There are also two thermostats in a water heater, one on each side.
When To Replace
The most obvious way you'll know that your water heater thermostat has failed is that your water temperature seems inconsistent. This can be annoying in terms of cold water, but downright dangerous if the heater doesn't turn off when it becomes too hot. Other issues with a Whirlpool water heater can be leaks, water pressure issues and drips, but they are unlikely to be the fault of your thermostat.
How To Check Your Water Heater Element Or Thermostat
When working with a water heater, you'll first need to ensure the circuit breaker is in the "off" position. Next, find the thermostat, which is near the top of your heater.
Remove the screws which hold the access cover on, then take off the access cover. Do the same with the other thermostat. Inside these access covers there will be an element and a thermostat. The thermostat measures the temperature whilst the element heats the water, so if either is broken the water heater won't work properly. You can buy a replacement Whirlpool water heater parts at Lowes.
The thermostat is under a plastic protective covering. Take this off and set it aside for later.
Check that the wires for the thermometer are in the correct terminals. Also check they are properly attached. If not, this may be responsible for your water heater issues and you may not need to replace either your thermostat or heater element.
If this isn't the case, you'll need to extract your old thermometer. Remove the wires and keep a note of which terminals they went into. Then, using a screwdriver, pry the thermostat away from the tank.
Align your replacement thermostat and clip it into place. Reattach the wires into their respective terminals, and secure. You can then put the thermostat covering back together. First replace the insulation, then the plastic shield, and finally the access cover.