How Does Gas Geyser Works? (Explained By Experts)

It is safe to say that you will buy a gas geyser and are most likely considering how it functions? Or on the other hand, would you say you are attempting to pick gas geysers but you are not aware of the advantages it offers?

Well if the answer is yes… then you are at the perfect place.

Gas geysers can provide ceaseless heated water while remaining energy effective as well as environmentally friendly, and how you may ask?

Then read along to find out more.


What is Gas Geyser & Why should you Buy One?

What is Gas Geyser & Why should you Buy One

Gas geysers have gained immense popularity, and due to their ability to provide hot water endlessly without wasting many resources, they are found in most of the households these days.

Gas geysers as the term imply, run on gas to heat the water. They use Liquified Petroleum Gas or otherwise known as LPG. Not only that, but they can be run on natural gas pipelines. Gas geysers have no limitations to provide hot water, that means you can heat the water as much as you would like.

These geysers are a way better alternative as they are cost and energy-efficient. Not only limited to that, they run on gas, meaning they do not need a single ounce of electricity to run. So you can easily get hot water even if your area is facing power outs.

They are affordable and provide hot water faster than other alternatives. Moreover, gas geysers are environmentally friendly, as they burn very clean, they do not produce any emission, thus keeping the climate clean and healthy.

There are many advantages of using a gas geyser and the most famous is, the fact that it can offer hot water on demand without wasting much time as well as resources. Besides that, they are great for small families as well as large families that have a constant demand for hot water.

Additionally, another best feature of a gas geyser is they can provide hot water even without electricity. This makes them an excellent choice for those individuals who happen to live in areas that are prone to frequent power cuts.

We would recommend getting a gas geyser if you are having a huge demand for hot waters; if you are a bachelor that runs late most of the time especially during winters; If you want hot water instantly.

Now, the mentioned ones are just the tip of the iceberg, a gas geyser is great for domestic use, as it is affordable, cost-effective, energy-efficient, and fast.


Types of Gas Geysers

Types of Gas Geysers

To understand the operation of gas geysers it is important to be acquainted with the types of gas geyser out there in the market. There are mainly two types of gas geysers, namely Instant Gas Geysers and Storage Gas Geyser.

Both of them do the same job and work almost the same, albeit in a slightly different way.


Instant Gas Geysers

The most prominent choice of individuals is instant gas geysers. As their name suggests, they provide hot water almost instantly. This is because of their low capacity and high heating rate that too of 3 kilowatts to 4.5 kilowatts (kW).

Most of the manufacturers sell instant gas geysers these days. With that said, due to their widely popular nature, they are often misunderstood or their names are interchanged.

Some other names of Instant Gas Geysers include Instantaneous Gas Geysers, Tankless Gas Geysers, and Natural Draft. No matter what you name them, they are great variants in gas geysers.

As mentioned before instant gas geysers have low capacity and thus they are great for small families that have hot water demand, not more than 120 litres a day, give or take a few.


Storage Gas Geysers

Storage gas geysers are like the rare birds in India. They are not much available in the Indian market these days. These types of geysers use tanks or reservoirs to store the water and then heat it accordingly.

Storage gas geysers are otherwise known as Tank Gas Geysers and sometimes Fan Force Driven. They are so rare that you can consider that they are not available in India. Ideally, storage gas geysers are required by large families or by someone who needs a colossal amount of hot water at once, for example, in the bathtub.

Since they are rare, they are not very popular in the domestic world. However, they are more efficient when compared to instant gas geysers as well as then can provide more hot water in a minute.

Now that you are aware of the types let’s understand the basic operation of these two types of gas geysers.


Basic Operation of an Instant Gas Geyser

Basic Operation of an Instant Gas Geyser


Instant gas geysers work on a simple yet smart mechanism. Before getting into the working part let’s look at the basic terminologies that we will come across. Pipes, Heat exchanger, Burner, Gas pipe, Valve, Flow Sensor, Thermostat and Fan.


Getting Started

The water pipeline is connected to the geyser with a sensor that detects the flow whenever you switch on the tap. The connected water pipeline is then covered on the heat exchanger in a serpentine pattern. The burner is below the heat exchanger that is connected to the gas pipeline. And just below the burner is the fan. The flow sensor and the valve through which the hot water will flow out, are connected to the circuit.


Hot Water Tap

At the point when you turn on or start the water tap, the flow sensor that is associated with the circuit detects the progression of the water and subsequently, the heating cycle starts. Don’t worry if you have a leaking tap, the flow sensor will not respond to that or small leaks.

Mostly the fan is not available in some gas geysers, but its basic work is to draw the air in for the combustion. So that the circuit starts the flow and ignites the burner.

Once the circuit has done its part the burner starts the flame and the sensor detects it.

If in the worst-case scenario, the burner fails to start, the circuit immediately shuts down the flow of gas to forestall any sorts of accidents.



The term you are reading circuit actually represents an Electronic Control Unit or abbreviated to ECU. An electronic control unit is the heart of most of the gas geysers and thus has a lot of responsibility in the working of the gas geyser.

It is the ECU who regulates most of the functions such as the gas flow, temperature control, burner, ignition, sensor, as well as modulation. ECU also handles the safety part, like switching off the geyser or cutting-off the gas supply in case of some problems.



The burner is connected to the ECU as well as the gas pipeline, as soon as the flow sensor detects the water, the burner ignites thanks to ECU, and the healing process starts. The fan below the burner aids with the combustion process by drawing in the air.


Heat Exchanger

Just above the burner lies a heat exchanger which is covered with the pipes in a serpentine pattern. So the maximum amount of the heat can be absorbed by the water from the walls of the pipe.

Some models of gas geysers have a secondary heat exchanger that works by heating the water before even reaching the heat exchanger. These models are sometimes referred to as condensing water heaters.


Heating Water

Now when the burner ignites, the heat exchanger gets hot and so do the pipes that are connected to the heat exchanger in a serpentine pattern. The water begins to move through the pipes and gets warm, eventually hot.


Water Temperature

The temperature of the water can vary and thus the thermostat adjusts the quantity of gas that flows and goes to the burner. This modulation keeps the water temperature fixed. This function is on the exit side of the heat exchanger in the form of a sensor.

The factory-set temperature for residential use in a geyser is around 50°C, while this temperature is pre-fixed, there are certain models of gas geysers that offer a controller to lower the temperature.

The controller can come externally in the form of a remote or through wired to some location.


Summary of the Operation – In simple Words 

So basically what happens is like this, when you open the hot water tap, the heating operation starts. The flow sensor detects the flow of water and ignites the burner. This ignition in the burner leads to heating the heat exchanger.

During heating the heat exchanger, the water flows through the exchanger in a serpentine pattern absorbing most of the heat. And comes out in the form of hot water through your tap.

The ECU maintains the flow and regulates the gas burner whilst the thermostat controls the temperature of the water that you will get from your tap.


Basic Operation of a Storage Gas Geyser

Basic Operation of a Storage Gas Geyser

Storage gas geysers or tank-type gas geysers work on a similar process but instead of providing hot water instantly they first store it in a tank. Before going deep inside the geyser let’s look at the terminologies. Coldwater supply pipe, Hot water discharge pipe, Tank, Flue, Burner, Regulator, Shut-off Valve and Tank drain valve.


Getting Started

The cold water pipeline is dipped in the tank to dispense the cold water and store it. In the centre of the geyser lies the tank in which the water will be stored. The tank has another pipe that is a hot water pipe which will discharge the hot water to wherever the supply is needed.

Just below the tank is the burner that is connected with a burner controller on the outer side of the geyser. Both the pipes come with a shut-off valve which aids in stopping the flow of water completely, during maintenance. In the centre of the tank is the flue which is connected to the chimney or vent pipe of your house to let out the exhaust gases.



The two pipes are dipped into the tank which is in the centre of the geyser. The cold water pipe is the one that provides the water to the tank for the heating process. The pipe has a shut-off valve which is used to stop the flow of water completely. You will find this valve in blue colour, at least in most of the storage geysers.

The hot water discharge pipe is the one that supplies the hot water to your taps, showers, sinks and other appliances that need some hot water. This pipe also has a shut-off valve which is mostly in red colour.



Coming to the heart of the storage geyser is the tank. The tank consists of a steel outer part which has passed the test of pressure and time. Similarly, the inner part of the tank is made from high-grade durable steel with some plastic layer to prevent the formation of rust.

Between the outer and inner part of the tank, there is a layer dedicated to the insulation that reduces heat loss. Inside the tank, in the centre lies a hollow flue—exhaust flue.


Inside Tank

Inside the tank, there is an anode which is responsible for preventing corrosion by drawing the rust towards itself. This anode can be found separately in some storage gas geysers models. However, some models do not provide a separate anode, instead, have a hot water pipe that is covered with aluminium or magnesium that works as an anode.

In the event that you find the hot water to be smelly or bad, the possible reason could be the anode has been consumed. In this case, you can easily replace the anode by yourself.


Regulator and Burner

The gas pipes are connected to the burner with a regulator that includes a thermostat. This thermostat, as you might know, measures the water temperature and regulates the burner accordingly.

The gas pipe that comes with the geyser is mostly made of copper tubing and has a shut-off valve. It is crucial to find where the valve is in your specific geyser so that you can easily turn off the supply in case of emergencies or while repairing.

Generally, this gas pipe is on the top of the model, but then again it depends on the geyser you are owning. The gas pipe also provides gas to the pilot light by the help of another small tube.



The flue serves two functions in a storage gas geyser, first is to exhaust the gases from the burner to outside and the second is, it works as a sort of heat-exchanger providing aid to the tank for heating the water.

In cases of the flue, they should be properly installed so that they can carry the air and discharge it outside. Different geysers come with different flue and it is important to be familiar with them.

  • Balanced Flue:- This where the air that is used for combustion and the fumes or exhaustion are extricated to the outside of the building. They can be installed on any wall in your house, given that it has enough ventilation.
  • External Flue:- This flue is connected to the outside through a chimney or some sort of vent. They take the fumes as well as the air for combustion and discharge it outside the building.
  • Flueless:- These types of geysers take the air & fumes and discharge them in the room itself. Thus, they cannot be placed in locations like a bathroom, bedroom, and sitting rooms. For this type of geysers, you will need adequate space and ventilation with an openable window.


Tank Drain Valve

With frequent use of water heaters, particularly storage water heaters, there will be some matter settled on the bottom of the tank called sediments. These sediments will not heat the water effectively, and you might hear some strange noises while the geyser is working. So the tank drain valve facilitates to cleans these matter. They are not so hard to clean by the way and you can do it yourself.


The Epitome of the Operation – In Basic Words

So what happens is, the storage gas geyser works on simple physics called convection, that defines how the water will rise. When the cold water starts to enter the tank constantly through the cold water pipe. The burner starts to heat the tank and the water gets warmer to the point where it rises up till the hot water pipe and flows out in the form of hot water to wherever it is called.

The burner heats the water while the regulator as the name suggests regulates the temperature. The thermostat controls the burner and switches it on & off accordingly. The flue exhausts the gases outside the building through a chimney or some sort of pipe.


That’s It

We hope that you got to learn about how gas geysers work in general and have probably figured out the benefits of using one. So do yourself a favour and go grab a gas geyser to make your winters more comfortable and enjoyable.

Gas geysers work on gas and thus are more energy-efficient, they are great if you want to reduce the hefty electricity bills. Plus, they don’t need electricity to run. They use gas to heat the water and are eco-friendly. What’s not to love?


Also Read:

Hindware Geyser Review

AO Smith Geyser Review

Racold Water Heater Review





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