Gas Geysers, Which One Should You Buy?

Here we will go over the types of gas geysers, their advantages and disadvantages and which one you should buy.

What is a gas geyser

Types of gas geysers



Before Diving in to which gas geyser you should buy, we should establish what it is first.

A gas geyser is a water heating system that runs of gas. The traditional South African gas geyser does not have a reservoir to store hot water, instead, it heats the water instantly. The gas geyser will only be activated when there is a demand. For example, if someone opens up the hot tap the gas geyser will activate and send hot water to the tap. When the tap is closed the gas geyser will deactivate and stop producing hot water.

Types of gas geysers

Fan Force Driven:

Fan Force Driven gas geysers make use of a fan to assist in the complete combustion of the gasses and then to force the combustion gasses through the heat exchanger. Fan Force Driven gas geysers are generally more efficient than Natural Draft and can supply a lot more litres hot water per minute.


Durability and Reliability:

Fan Force Driven Gas geysers have a much longer lifespan thanks to superior parts and better design. The longer life span of these geysers makes a lot more sense for customers who want to save more money in the long run. They also (depending on the model) have much longer warranty periods for certain parts. Fan Force Driven Gas geysers are also a lot more reliable, you do not need to worry about the wind blowing out the flame of the geyser on a windy day or worry that the temperature is too cold that it will freeze up the unit.


Force Driven Gas geysers have far better efficiency again making them the better choice for those who want to save big in the long run. Most Force Driven Gas geysers can be connected in conjunction with solar geysers meaning the geyser will either use a lot less gas or the geyser would not turn on at all.


One of the main draws to a Force Driven Gas geyser is that it can regulate its output water temperature on the fly. meaning that you can set the geyser to your target temperature and that’s what the geysers will give you, so that you do not waste money by adding cold water in the case that the water is too hot. You set the temperature before use and that’s it, no need to add cold water.


Force Driven Gas geysers have better / more safety features making them the better choice when choosing a gas geyser for those who are more safety-conscious.

Water Flow and Pressure:

Force Driven Gas geysers do not restrict the flow of water except in extream circumstances. They also require very little water pressure to operate. Certain Force Driven Gas geysers can be joined together to supply very large amounts of hot water, very useful for commercial applications.


Though Force Driven Gas geysers are more complex internally they are much simpler to install and do not require all the extras that Natural draft geysers require, like a weather cover and flu/chimney. Thanks to the added sensors in Force Driven Gas geysers, they are much simpler to repair and troubleshoot as they have built-in diagnostic systems that make determining a problem much easier. (read “Complex internals” on the Disadvantages of Force Driven Gas geysers before making up your mind).



The main disadvantage with Force Driven Gas geysers is there cost. they can sometimes cost 2 to 3 times more than Natural draft geysers.

Electricity Dependant:

Though Force Driven Gas geysers use a very small amount of electricity to operate the fan (around 60 watts) they still require a 220v AC power supply. however, they can run off a generator or a pure sinewave inverter.

Lightning Susceptible:

Because they are plugged into the wall there is a risk the unit’s electronics could be damaged by lightning strikes.

Complex Internals:

Newer technicians are more likely to be unfamiliar with servicing and repair of Force Driven Gas geysers due to there added complexity. However there superior durability and reliability make this less of an issue.

Natural Draft:

Natural Draft gas geysers make use of the natural principle of hot air rising. The hot gasses produced from combustion rise up through the heat exchanger and then, in most cases, through a chimney, which normally assists in the draft.

How chimneys work:

Why Hot air rises:



Natural Draft gas geysers are cheaper than Fan Force Driven Gas geysers. Just be sure you are not paying the same or close to Fan Force Driven Gas geysers prices when you factor in the costs of the weather cover and flu/chimney.

No AC Power Needed:

Natural Draft gas geysers do not require 220v AC to operate, they only require 2 torchlight batteries to operate. This is great for those who do not have access to alternative power supplies or for those who just want a simple backup hot water supply.


Most technicians are familiar with Natural Draft gas geysers making repair easier, in the event the unit breaks down.


Durability and Reliability:

Having owned multiple Natural Draft gas geysers I can (unfortunately) say that they are not reliable or that durable. Whenever it was windy or rainy my Natural Draft gas geysers had problems starting up, even with the required weather cover and flu/chimney.

Water Flow and Pressure:

Natural Draft gas geysers, by design, need to restrict the flow of water passing through them in order to increase the temperature of water flowing through them. This can lead to disappointing flow rates for those who do not have high incoming water pressure.

Also, Natural Draft gas geysers are very sensitive to water pressure changes and require relatively high water pressure to operate. For example, most Natural Draft gas geysers will shut down if the user tries to use the cold water while the unit is in operation because of the loss in pressure, the unit will shut down.

Extra Costs:

Most Natural Draft gas geysers require a weather cover and flu/chimney which make the unit cost more than expected and in some cases, it may make more sense to buy a Force Driven gas geyser for a little extra money.


Regardless of the type of gas geyser if you require water for a shower or multiple applications you should look at a 16 liter per minute and up gas geyser. If you only require a small amount of hot water (a single sink or basin) a smaller than 16 liter gas geyser will be adequate.

If you are looking to save the most amount of money we highly recommend getting a Fan Force Driven gas geyser. Their Efficiency plus reliability and durability make them the best choice for those who want to save as much money as possible.

If you do not have access to an alternative power source when the power goes out then the Natural Draft gas geyser is for you. Unfortunately, there is no getting around the fact that Force Driven gas geysers require power, but with Natural Draft gas geysers that is not a problem.

If you have low water pressure you will have to get a Fan Force Driven gas geyser or a zero start Natural Draft gas geyser. alternatively, you can get a booster pump to increase your water pressure however then you are in the position of not having water when the power goes out, which would make the Force Driven gas geyser a better option.

If you only want to operate a single sink or basin then a Natural Draft 16 litre and under gas geyser will be adequate. Fan Force Driven gas geysers would be overkill.

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