Difference between a gravity and pressure solar geyser – What you should know before buying your next solar geyser

Suntask Solar Geyser at KumbaDirect

Read this before you buying your next solar geyser – What is the difference between a high pressure often referred and Pressure Geyser v low pressure geyser, often referred as low-pressure geyser.

There are two types of solar water heater also known as solar geyser, pressure and non-pressure geysers.  For pressure geysers, water in the tank is under high pressure, being the same as the pressure of the tap water. For gravity geysers, water in the tank is under low pressure, and is the same as the gravity of the water.

Before you decide to buy, you should know the difference between the gravity and pressure geyser to see which is ideal for your requirements.

The Pros: 
It can heat up even if the tank is not full, working well where there is erratic water supply

This type of solar heater is simple, with no moving parts.
Due to its simplicity, it is usually a cheaper option
Due to lower pressure and stress on the tank and collectors, it has a longer life than mains pressure solar geyser systems.
This type of solar heating system is lightweight.
Can provide hot water without external power, so ideal for remote off-grid installations.
This type of solar geyser system is highly effective in converting sunlight into heat

The Cons 

Cold water has more pressure than warm water, so it’s not ideal where installed without a mixer

Its use is limited in modern plumbing systems, as it can only be used where there is small head of pressure.
Unless it is installed at a high level above the water outlets the water pressure will be very low.
It can cause serious scalding if not installed or used correctly.
The entire solar heater system needs to be shut down even if one glass tube breaks.
All the weight of the heater is carried by the roof which may need additional support
The tank does not look very attractive when installed on top of a roof
It breaks easily.


The main advantage is that the water pressure can be very high.

Cold and warm water comes out with the same pressure, making it convenient without adding extras to help with that
Works well with water pumps that have been installed
There does not have to be an ‘unsightly’ solar heater water tank on the roof.
They can sometimes be retrofitted to use existing storage tanks.
The tank or collectors can be located in more accessible or appropriate locations.
More robust than low pressure systems

They are more expensive than low pressure solar heater systems
Some models require power to run the pump and temperature differential controller – this can be overcome by installing a photovoltaic module.

It would need a constant supply of water for it to run smoothly, as it won’t funvtion well when tank is not full.

What geyser type you would choose depends on your preferences after assessing both the pros and cons and assessing your personal circumstances regarding each point. is a leading supplier of solar products and offers monthly affordable payment options to buyers in selected countries. We supply both pressure and gravity geysers. To shop and discuss your options, visit the website on choose what works best for you. Discuss and find out more on 


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