What is a Tank-less or Instantaneous Gas Water Heater?

Meant as a turnkey replacement for your existing electric or solar offering, our range of tank-less water heaters only heats water when you need it

This means you have an endless supply of hot water available whenever you need it. It also means you save money on energy costs by not reheating the reservoir water in the storage tank when you are not using it.

Available in a range of sizes and price entry points, we are able to service everyone from Jo needing a small specialised heating solution for her home scullery to Susan looking for a complete green solution for the ablution facilities of the new gym she is architecting.

What are the real advantages

  • Instantaneously heating water means an endless hot water supply. No more nervous times spent wondering if it' s your imagination or is the water getting cooler 'cos it's the last water of the hot water. No more dodgy "coffee every morning for a week" deals on a Sunday morning to be the first to shower
  • Because of their diminutive size these units are easily concealed in small spaces or better still installed outside where access to oxygen for combustion is not a problem. Units installed outside should always by sheltered inside a weather proof box.
  • No risk of a trashed ceiling and house full of water from a burst geyser in the ceiling, instantaneous means no storage tank lurking in the roof waiting for the first opportunity to destroy that new Persian rug
  • No storage of water means no lurgies floating around for years in the bottom of the tank. Because hot water rises, the outlet fitting on a tank storage water geyser is mounted at the top of the tank, anything that sinks in water that washes into your geyser is there for good. Dinkum. Just think about it.
  • We have seen many units in the field with lifespans well in excess of 20 years, I kid you not, instantaneous gas water geysers were the standard for many rural settings when electricity was not available in darker days past. Talk about longevity
  • Instantaneous!!! as in the water is heated only when you turn the tap on! It puts you in control of exactly how much energy you consume, shorter shower means a lower energy bill. Period.
  • Green sustainable energy. Not only is burning gas substantially less impactful on the environment than electricity produced by coal, these units are also considerably more efficient than the electrical storage solutions (by as much as six or seven fold in many cases).
  • No change in lifestyle required. Because you are not dependent on when the sun shines or when the wind blows you can choose when you shower and for how long without compromising on your hot water expectations
  • You can be in control of your own destiny. Gas is the ideal energy solution for the South African consumer. It is an easily transported, easily stored and easily exchanged cheap energy source which can meaningfully reduce your dependency on Big Brother for your heating and cooking requirements. Keep a spare bottle handy you will never experience rolling-blackout style energy turmoil again.

Combustion Types

Fan Assisted

fan assisted gas geyser In order to squeeze higher kilowatt output and a higher efficiency ratio (47KW and 94% in the case of the Bosch) out of the units, the top end models make use of an electrical fan (160W) to premix the gas and air in the combustion chamber. This process is functionally very similar to a turbo charger on a car. As a side effect these units require power to operate, but because of the low consumption it is possible to fit battery backup.


traditional gas geyser Employing essentially the same technology for the last 100 years these units use no electricity but are unable to come close to the power and efficiency of the fan assisted units. There are essentially two tiers of traditional gas geysers available, the mid-range European imports who's units generally are leading the way as far as innovation and built quality are concerned, and the less pricey but at the cost of quality Chinese models.

Which one should I get?

Depends. The largest of the traditional models will happily service the demands of a single domestic bathroom, when more than one bathroom is involved questions like how far apart they are and how many taps will be opened at the same time become pertinent. Best contact one our trained consultants for further advice.

In a commercial setting it almost always makes sense to consider one of the fan assisted models where both efficacy and efficiency are dramatically improved. If the geyser is likely to be operational (as in heating water) for more than a couple of hours a day, the up-front costs are quickly recapitalised in reduced operating costs on account of the higher operating efficiency.

Gas Water Heating Solutions

Fan Assisted Models

Bosch Thermotechnic

  • The Gas Company Best Buy
  • 94% efficient
  • Solar Backup Ready
  • 24 Hour duty cycle
  • Remote operation possible (radio)
  • 1 Year call out Guarantee
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bosch gas geysers
Mid-range European Models

Bosch Traditional

  • Over 30 years in SA Market
  • No pilot flame
  • 11 and 18 litre models
  • Outdoor + flue kits available
  • Installation kits available
  • 1 Year call out Guarantee
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bosch gas geysers
Budget Friendly Models

Atlas Geysers

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atlas gas geysers

What about installation

Gas geyser installations are all about two things:

  • Water plumbing
  • Gas reticulation

Water Plumbing

The instantaneous water heater is plumbed in-line into the existing water piping network, this translates into very simple plumbing requirements. Effectively you connect a cold water supply to the inlet, and a hot water draw to the outlet. No further magic is required. No breaker valves or pressure relief required.

This task can easily be performed by whoever is generally responsible for the upkeep of the home.

If you are replacing your existing electrical or solar solution, you simply take the cold water going into your existing geyser and reroute it to the new gas geyser, do the same for the hot water and you're done.

We recommend that you put the new gas geyser as close as possible to the outlet where the most hot water is likely to be consumed. This reduces the time you wait for hot water to arrive at the faucet and also reduces the loss of heat due to exposure to cold air through the piping in the winter months.

Gas reticulation

The installation of the gas component bears a little more consideration due to the flammable nature of the product. Fortunately there are clear best practices which are supported by a regulatory set of laws that dictate the requirements for the safe operation and installation of a gas supply to a domestic dwelling or commercial establishment.

We at the gas company have assembled an installers starter pack to assist in simplifying the whole process. The kit includes everything an installer requires to carry out a basic permanent outdoor gas installation in kit form. All that is required in addition to the kit is the bottle supply and a cage to house the bottles safely.

In much the same way as electrical compliance certificate is used to prove the compliance of a building as tested by a certified professional, an LPG compliance certificate is required by legislation when selling a property with a permanent gas bottle supply. Any LPG gas installer with valid South African qualification can check and certify any LPG installation for compliance to the code.

For more information why not have one of our trained sales consultants get back to you to walk you through this step of the process.

Frequesntly Asked Questions

What does quoted flow rate actually mean?

Great question. The international metric for measuring instantaneous water heater performance is in litres of hot water per minute at a temperature delta of 25 degrees celcius. In other words a 18L geyser heats up 18 litres of water per minute by 25 degrees, smaller change in temperature means more water flow, but hotter water means less flow.

What does quoted gas consumption actually mean?

Think about it, these geysers need to heat water by 25 or more degrees instantly, this kind of power demands a high burst rate of gas. This discussion can get technical (liquid to gas conversion rates) but the bottom line is at least one large bottle (we generally recommend more) and a large (> 1KG/Hour) regulator is required

Indoors or Outdoors?

Both indoor and outdoor options are possible, and there is a time and place for both solutions. We at The GAS Company always suggest that an outside installation is almost always preferable over inside. The reason is simple, burning anything (combustion in any form) uses up oxygen. If your unit is installed inside you and your geyser are in reality contending for the same oxygen.

Obviously the bigger the room the less relevant this whole discussion becomes, but generally speaking outside is better

What about the gas installation?

see our section on external domestic installations

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