At the heart of any electrical water heater is the thermostat. So if you are getting cold water instead of the regular hot water, then either you will need to repair the water heater thermostat or replace it. Although installing or replacing a thermostat may sound difficult and too technical; it is quite the contrary.

But the important thing to remember is that it might not be the problem of a thermostat at all. In order to confirm the same, you need to check the thermostat using a voltmeter and a multimeter. If you think that the problem lies with the thermostat, then the first thing you need to do is identify the type of water heater thermostat you require. You can find that out by identifying the type, model, and brand of water heater you have installed. This is important because water heaters are primarily of two types – tankless and storage. The next thing to identify is whether you are using an electric water heater or is it driven by propane, solar energy, or natural gas. Last but not the least, identify the brand.

Most often than not the water heater thermostats will be available at the brand outlet and all you have to do is provide the model number. But in case it is not available there then you will need to get the replacement from another store. Hence, knowledge of all your requirements will be quite useful.

How to Install and Check a Water Heater Thermostat

Step 1: Switch off the power connection to the water heater

Step 2: Remove the access panel and check both the upper and lower access panels. If you have an electric water heater then it will have an upper as well as lower thermostat for controlling the upper and lower heating elements. You will need to test both thermostats as you might have to replace one of them or both.

Step 2: The next step is to lock off the circuit breaker and don’t forget to remove the fuse. Once this is done, remove any insulation blocking your view and the plastic shock protectors.

Step 3: A water heater thermostat always has a graduated adjustable dial with letters A, B, and C indicating various degree of heat. The thermostat in electric water heaters is normally situated right under the high temperature limit switch. Right under the thermostat is the heating element.

Step 4: Now switch the power on so that you can check the thermostat.

Step 5: Now set your multimeter to ohms or resistance and observe the meter readings. In a digital multimeter, the readings will show “OL” or 1″ without any leading or trailing zeros. The readings OL or 1 represent a value that is greater than what the meter is capable of displaying for infinity or overload. Remember, infinity within a high resistance range will be known as an open circuit or OL (open loop). Write down the open circuit indication for this meter.

Step 6: Now remove the red test probe from the Ohms jack of your meter and insert it into the volt. At the same time, you need to set the range of the multimeter to the lowest voltage value, which should be greater than 240 Volts VAC or AC.

Step 7: Now start by checking the top heating element terminals. They should show a line voltage of 120, 208 or 240 volts. If it doesn’t show any power readings then check the bottom heating element as well. If either one or both don’t show any voltage value then there is a definite problem with the thermostat.

Step 8: Now turn off the power again and disconnect all the wires from the thermostat terminals.

Step 9: Use a screwdriver to remove the water heater thermostat from its mounting. Put the new thermostat in place and screw into the mounting. Connect the wires to the thermostat terminals.

Step 10: Repeat the process if the lower thermostat also requires a replacement.

Step 11: Now connect the access panel to the water heater and turn on the power.

At any point in time, if you have the slightest doubt then call a professional to do the installation as there is always the danger of getting electrocuted.

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