Water heating is an essential component that must be done right to avoid significant energy costs. Any kind of heating or cooling system consumes a lot of electricity. Therefore, maintaining an optimal temperature is the key to save power usage.

Water Heater Thermostat Settings

To help conserve energy, most modern water heaters come with a thermostat.

Not sure what a water heater thermostat is and how it works?

Read this article to know everything about a thermostat.

What is a Water Heater Thermostat?

Water heater thermostat is typically a thermistor that produces a small amount of electric current to respond to heat.

When the water temperature rises and reaches the desired level, the thermostat will cut off the power supply. Again, when the water temperature drops, the thermostat will function towards generating more power to heat the water optimally.  

Fluctuations in the production of electric current cause the water heater’s gas valve control to turn ON and OFF.  

Thus, the thermostat will ensure that the water is heated till the set temperature and then turns off the power supply. The power is turned on again only when the water temperature falls below a particular level.

By regulating the water temperature and continuously switching off and on the power, a thermostat helps save a lot of electricity. This can help cut down on your energy bills significantly.   

Where is the Thermostat in My Water Heater?

Does not know where exactly the thermostat is located in your water heater?

Typically, there are two types of water heaters available in India – one where the thermostat is visible and has settings that can be changed easily; the other where the thermostat is placed internally and the settings cannot be altered.

The water heaters with changeable thermostat settings will have knobs that can be rotated to alter the temperature levels.

On the other hand, the latter has pre-configured temperature settings ranging from 55-60 degree centigrade. These typically have red and green lights that indicate whether the water is heating or not.

Technical Characteristics of Water Heater Thermostat

The Bureau of Indian Standards validates the following technical specifications for thermostats in electric water heaters, geysers, etc.

Stem length175 mm, 275 mm, 450 mm
Insulation Level1 KV for 1 min
Tolerance on operating temperatureWithin 4 °C or Customer defined
Temperature DifferentialWithin 10 °C
Temperature range of operation25-75 °C (other ranges on request)
Contact configurationOpening on temperature rise
Contact Rating20 A, 230 V resistive

Different Types of Thermostats

When buying a water heater, you may come across three different types of thermostats that are powered by unique technologies. Let’s understand these here quickly:

  1. Stem Thermostat: The “plugged-in” thermostat is reliable and affordable, featuring a long stem that expands when the temperature rises. This causes it to cut-off the power supply when the temperature reaches the pre-set temperature level.
  2. Bulb Thermostat: It is also known as capillary thermostat and is more precise and reliable. The bulb of the thermostat is filled with a heat-reactive fluid that increases or decreases in volume with fluctuations in heater temperature. This causes the thermostat to stop or trigger heat production when the temperature increases or falls beyond the set level.
  3. Digital Thermostat: This is even more precise and allows you to set a wide range of temperature points. It contains a thermistor that leverages electrical resistance to measure variations in temperature. The resistance value will change with fluctuations in water heater temperature.

What Should be the Ideal Temperature of My Water Heater?

Not sure what should be the optimal temperature of your water heater?

The ideal temperature in a water heater is approximately 50-degree centigrade, suitable for all kinds of purposes.

In India, most water heaters come with a temperature range varying from 40-75 degree centigrade. That means if you want the hottest temperature thermostat setting, it should be 75 degree.

Set the temperature knob of the water heater in the center or middle position to have the right amount of heating and energy savings.

It is important to understand here that the total amount of energy consumed by the water heater will be dependent on the thermostat setting and temperature of water coming into it. If the difference is significantly more, then energy consumption will be more.

Does the Thermostat Switches off the Water Heater When the Heating Temperature Reaches the Set Level?

Often people think that the thermostat will switch off the water heater when the temperature reaches the pre-determined level. This causes them to keep the heater turned “ON” always thinking that the thermostat will switch it off automatically.

However, this is not the case. Whenever the temperature falls by certain degrees, the heater will turn on again. Eventually, this will result in significant loss of electricity.

So make sure you switch off the water heater always after use.


Understanding how a thermostat works can help you use the water heater wisely, improve its performance in the long run, and reduce your energy costs.

How to Check Water Heater Elements & Thermostats?