What is a Water Heater Thermostat? Everything you need to Know!

Hot water is a necessity in the winter months, and most people cannot live without it. If suddenly the water heater of your home stops operating, then you will know the significance of the device in your daily routine. We all have faced the problem of a water heating machine not creating sufficient warm water. In that scenario, you can call a professional plumber or can fix it by yourself as most of the water heater models can be easily repaired. Water heater primary fails due to two reasons: one is a heating element, and the other is a thermostat. There are different types of water heaters present in the market like gas, fuel, and electricity. Each of them operates differently yet serve similar functions.

The thermostat of the machine is the most commonly failed or damaged part. In a thermostat failure case, you will not be able to set and gauge the hot water until it is repaired. You have to maintain the thermostat integrity to keep the water from reading any scalding temperature.


Definition of a Water Heater Thermostat

Thermostats in a water heater are a type of thermostat that can control the outgoing water temperature. They are mounted on the surface with the help of a bracket to hold any element against the tank side. The thermostat back is in full contact with the tank, and thus it reacts to the tank temperature changes rapidly. In the water heaters with storage tank, thermostats are present at the backside of the access panels.


Purpose of Implementing a Thermostat

Each electric water heater comes with a heating element for warming up the water, a thermostat for controlling the temperature, and a high limit switch for protecting the machine from excessive temperature. Various hot water temperatures are necessary for different applications like washing clothes and dishes, and showers. The primary principle of implementing a thermostat is to manage the overall temperature of the water and controls the electrical current sent to another thermostat for adjusting the temperature.

Electric water heaters with 30 gallons or more storage tanks come with two thermostats and heating elements. The thermostat present in the upper part is the primary one includes a high limiting switch. The thermostat in the lower portion can feel the temperature of the water at first. The upper thermostat present is not the same as the lower thermostat, and both do not perform simultaneously.

The higher limiting switch includes a manually resetting ECO button and is present in a similar section to that of the uppermost thermostat. This button trips down when there is a presence of very high water temperature of above 70 degrees Fahrenheit. When you press the ECO reset button, the device is ready for performing the standard operation. But if the tripping continues to occur more than once, then you should carry out an examination.

When you control the thermostat in a water heating machine, set both the thermostats at the same temperature or set the uppermost element by slightly lowering the temperature. It will lower the heating element by getting activated first and warms up the water from the bottom to the top. Machines with a lower capacity implement only one heating element and a thermostat. They operate at a temperature of 120 volts and also include a high limiting switch.


How does the Thermostat of an Electric Water Heater Operate?

When you start noticing that the water heating machine is not supplying enough as it should be, then the thermostat might be the problem. There is no necessity of replacing the entire unit if you want to save money and time; a simple thermostat will do the needful. Thermostats in a water heater operate by closing and opening the contacts that allow the electricity to flow through the heating elements. The heating components come with architecture for cycling on and off based on the demand.

All the modern and latest water heaters come with two thermostats and heating elements. Two panels are present on the machine’s side, each of which consists of a thermostat and a heating element. The uppermost thermostat is entirely different from the lower portion. The uppermost thermostat is larger and manages the lower one. When the upper part of the thermostat or heating elements fails, the entire device stops creating hot water. When the lower portion of the thermostat or heating elements fails, the uppermost component and thermostat will continue to warm up the water on the topmost side of the tank. But you notice that the water coming out from the faucet is only lukewarm.


Is the Concept of Thermostats in a Water Heater Universal?

No, the concept of thermostats in a water heater is not universal. There are numerous variants of the single and double element water heaters. In dual water heating machines, there is an enormous difference in the lower and upper thermostats. You need to know the number of water heating elements and the voltage it will require to operate. You can look out for this information on the side of the machine body.

If there is no such information present, then you have to determine the dual and single elements according to the number of panels on the device. Mostly the residual heating machine for the water is 240 volts. There are innumerable water heater models present in the market where the thermostats are interchangeable in most of them. You should always check out the product description carefully before buying and installing it in your house.


Single Element Thermostats

In single element thermostats, total wire terminals are different from that of the dual element thermostats. It consists of two terminals on the right portion and four on the left portion.


Dual Element Thermostats

In a dual element thermostat, there are upper thermostats with a high limiting switch identified by the red resetting buttons. The machines also consist of lower thermostats.


Ways for Testing the Thermostat of the Water heater

The user should always check the thermostats for the continuity of the machine. This process will decide if the device has failed or not. For accomplishing this, the user will need a digital or analog multimeter. You can test the thermostat in the following ways.


Switch off the power


You have to switch the breaker of the water heater off from the circuit board. The breaker is present inside the panel box, which includes a label as hot water or water heater.


Remove the access covers on the outside.

Implement a flathead screwdriver or 1/4th inches nut driver for removing the lower and upper thermostat accessing panels. You require folding back the insulation for the thermostat. Use tape for securing the insulation and get rid of the plastic covers on the inside over the thermostat.


Confirm the power is switched off

Before handling the thermostat, implement a multimeter to confirm that you have switched off the power of the water heater. The user can utilize a voltage stick as well. If you are using a multimeter connection, you have to touch the legs simultaneously. The meter reading should be 0. When the black connector touches every leg, it will confirm that there is no presence of power.


Examine the High limit resetting button

You also need to study if the machine has tripped the higher limit resetting button. There can be many reasons for tripping that are:

  1. The contacts of the thermostats have been fused close
  2. The thermostat is calibration less.
  3. Failure of the heating element


Disconnection of the wiring

Use a digital camera or a phone for snapping an image. It will offer a reference if required for the wire identification and which one is connected to whom. You can disconnect all the wiring on each thermostat terminal with a screwdriver.


Examine the Thermostat again with a Multimeter

With the help of an analog multimeter, set it to the lowest 10 ohms of resistance. You also have to calibrate the meter by adjusting the needle to 0 and pinching the probes altogether. If you are using the digital multimeter, set it to the lowest resistance ohms. Take any of the black multimeter probes and place them on the left portion of the screw terminal. Similarly, place the red probe on the left side of the terminal. If the terminal includes continuity, the meter reader will be close to 0. If it does not show anything, then the thermostat has failed and requires to be replaced.

The user has to again do the procedure for the right side and the element terminal. If the uppermost thermostat is okay, you have to reestablish the wire and seal the accessing panels or continue to the replacing steps of the thermostat. If the thermostat seems to be alright, then you have to examine the heating elements next.


Ways for replacing the Thermostat of a Water Heater

Once you have known which thermostat is damaged, you can start removing the thermostat and install it. If you have already tested the thermostat before, then start with the following process.


Eliminate the Defective Thermostat

With the help of a flathead or old screwdriver, remove the thermostat by pressing on the clip outward. After that, lift the thermostat upwards and take it out from the retaining bracket. Be careful about not breaking the retaining bracket as breaking it would cause you to replace the entire machine.


Inserting the new Thermostat

Put in the new thermostat by inserting it into the same place of the retaining bracket that will hold it in a proper position. Reconnect the wires in their position firmly. Ensure that the thermostat is placed firmly against the water heater as the water heating machine will not operate properly. Next, control the thermostat to the desired temperature or a maximum of 120 degrees Fahrenheit. The temperature setting in this device is exceptionally significant as the higher temperature might become a hazard for the children.


Reattach the Covering Panels

Now that you have done all the replacement work, you have to seal every cover by putting on the insulation and protective plastic cover. Now reattach the access panels on the outside.


Put on the Power

When everything is connected and is working in perfect condition, turn on the breaker in the electrical box. It will take almost one hour for the water heater tank to recover fully, and you will start getting hot water 15 minutes after that. Also, ensure to check the machine periodically to examine if anything is wrong or not.


Wrapping It Up

Replacing the thermostat in a water heater is not too challenging and can be done within a few minutes. You have to avoid taking any shortcuts as the process is safe and quick. So when you are looking for a water heater, know if it includes a single or dual element thermostat and the heating element voltage.


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