150 litres (18 x 1800mm tubes)

200 litres (24 x 1800mm tubes)

250 litres (30 x 1800mm tubes)

Cheap for the quality, but still in the more expensive class.

Roughly half the price of the high pressure systems.

Five years, if installed to specification. Glass tubes are not guaranteed against breakage. Electrical parts:one year, or according to manufacturer. 

If you want to keep your municipal or pressure pump pressure, choose a high pressure system.

You will have less available hot water compared with the low pressure systems. 

If you want a cheap system that works well, choose a low pressure system.

You will probably have a lower pressure at the tap.

Please reconsider if:

• there are 15mm pipes in the wall, especially to the bath,
• there are expensive one armed mixer taps. This will restrict the water flow substantially.

Exactly the same

Because the tank is closed, heat retention is better than the low pressure systems.

 There is a breather in the tank, which causes more lost heat than the high pressure systems.

1.2mm stainless steel. 5 Years guarantee.

 A good quality stainless steel vessel, 0.41mm thick. Strong enough to last for many years at this pressure.

 These tanks are heavier, up to 43kg.

 Low pressure tanks are light. This makes installation much easier.

 Exactly the same. Like with any geyser, regular replacement of the anode makes the geyser last much longer because it reduces rust and scale buildup substantially.

600k Pa (6 Bar or 60 metres) working pressure.

Like with a normal geyser: high pressurein, high pressure out.

About 20 kPa (0.2 Bar or 3 metres) maximum.

Designed to use gravitational pressure from the water level in or above the tank.

It has to be open to air to let the steam out when it boils.

 The standard 1800mm length x 58mm diameter x 2mm glass thickness tubes are used.

These tubes are designed to withstand 38mm diameter hailstones.

 Present. Filled with a low boiling point fluid, it causes an effective heat transfer cycle.

 None. The water in the tank also circulates in the inner glass tubes.

 None. There are heat pipe inserts inside the tube. They gather heat from the black inner tubes and gives it off into the tank.

Present. The collected heat energy gets transferred directly to the water in the tubes.

 Almost exactly the same for both types.

 The stands are well designed, so that the mass is spread among the feet. This means a relatively small load per foot. (The heaviest is 74kg per foot)

This is optional. Standard South African electric elements are used. It can be controlled with a standard thermostat or an electronic controller..

 A programmable timer switch which is usually installed inside the house. Shows the water temperature, time, if the element is on, etc. Available with or without battery backuop.

By default it senses the temperature inside the tank between 4 and 5am, and, if the water is cold, it heats the water electrically to 60 degrees Celsius. Between 5 and 10pm it does the same again, if necessary.There is also a manual button which makes the water heat once to 60 degrees Celsius.

 More expensive.

 Lower water pressure at the tap.

 To keep the pressure, a litre of cold water must replace every litre of hot water used. This means that the water temperature comes down as water gets used.

If both the outer and inner tubes break, the water in the tank will run out. This very seldom happens. The system will only work if all the tubes atre installed.