Instant Geyser vs Storage Geysers / Water Heaters!

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When you venture into the market to buy a best geyser, you encounter a dilemma whether to go in for an instant geyser or a storage geyser. Both these water heaters have their advantages and disadvantages.

We have already seen the comparison from the space angle (ideal water heater size). Let us look at the more important angle of power consumption.

Normally, one buys instant heaters for small uses like wash basins and kitchen sinks. It is easy to install such geysers at these places. Let us look at the larger picture now.

What is an instant water heater?

Before we move any further, should we not have an idea as to what constitutes an instant heater? As the name suggest, this appliance supplies hot water almost instantaneously.

Naturally, you expect these geysers to have very low storage capacity in the range of 1 to 3 litres. Anything over 3 litres constitutes a storage geyser. As this appliance heats the water instantly, they have a higher wattage in the range of 3 to 4.5 KW.

Time taken for heating water

In the winter months, the temperature of the water in India can be between 4C to 21C. Water below 4C will not be able to flow through pipes easily as they tend to become ice.

Consider the ideal conditions where we consider the optimum temperature as around 400C and the peak temperature at 60C.

When the input water is at around 15C, the instant heater can cake around 2 minutes to heat the water to 60C and about 1 minute to heat it to 40C. In case the input water temperature is higher at 21C, it will not take more than 20 seconds.

Storage water heater
15 litre Storage water heater

Water flow rate

This is an important feature. The quality of heat depends on the flow rate of water from the taps. In the normal course, the tap flow rate is around 3 litres / minute and showers have a rate of 8 litres / minute.

Thus, if you have a 3 litre instant geyser, the water in the geyser will heat up almost instantly as you empty the tank. In the case of showers, the flow rate is higher. Hence, you do not get water at the right temperature to bathe.

This is the ideal situation especially in cities where you have the input water temperature at around 21C. In colder cities, you will not get a continuous flow of hot water. You will have to wait for some time. Imagine doing so on a cold morning inside a wet bathroom. It can dissuade the strongest willed person as well.

Where can you use instant water heaters?

As mentioned earlier, these geysers have great use in kitchens and washbasins where the usage of water is less. In case you wish to use them in bathrooms, the geysers might serve you right if you belong to the southern part of India because the input water temperature will be in the range of 20C. Otherwise, it is always beneficial to opt for the storage water heaters.

Drawbacks of Instant heaters

If you go through the above paragraphs, you will infer that the standing loss will be at a minimum. Hence, there does not seem to be any power wastage. Therefore, they look great from an individual’s point of view. We shall look at the overall picture.

The instant geysers have the responsibility of delivering instant hot water at optimum temperatures. The power consumption is on the higher side in the range of 3 KW to 4.5 KW.

The storage geysers consume 2 KW of power in the bargain. If you heat 15 litres of water, both the geysers will consume the same amount of power. The only difference is that the instant geysers take less time. However, they put more load on the system.

Now, consider the situation in a city like Delhi. A majority of people in the city take bath between 7 am to 9 am. If each house used an instant geyser system, the load on the main grid would be tremendous leading to a grid failure.

However, the storage geysers can balance out the equation as they consume the same power over a longer period. There will not be a sudden spike in the demand.

In case of instant geysers, the fixed cost can escalate. Therefore, you might save money in the short run but transfer it to fixed costs.


In the overall scenario, the storage geysers are better than the instant geysers.

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