Sized in litres a minute
Matched to the outlets that run at once, because a unit sized for one shower goes lukewarm when a second tap opens.
Home / Gas Geyser Installation
Gas geyser installation in Durban starts with a pressure reading, not a brochure. Every gas water heater fires only inside a range printed on its datasheet, and a rationed supply can drop below it at certain hours. The supply is measured first, then the unit, the siting and the gas certificate follow.
Tell us how many showers and basins need hot water at the same time, and whether the geyser would go outside or inside. If you know the hours your water pressure is weak, that helps most of all.
The unit is the part you see. The water side, the gas side and the flue are where an installation succeeds or fails.
Matched to the outlets that run at once, because a unit sized for one shower goes lukewarm when a second tap opens.
Read at your worst hour against the unit's minimum, and overnight against its maximum, before anything is ordered.
Fitted where your supply can exceed the unit's rating, which on some datasheets sits below the by-law's own limit.
Some models are rated for outdoor use only, under a weather cover, and are installed exactly that way.
Indoor models with the flue run outside as the maker specifies, or room-sealed units on their own balanced flue.
A Certificate of Conformity from a practitioner registered for gas, which is a different document from the plumbing one.
An electric geyser stores hot water and barely notices what the supply does for the next few hours. A gas geyser has no store. Water is heated on its way through the unit, and the burner lights only once enough of it is moving to trigger it. That threshold is not luck or temperament. It is printed on the datasheet.
Published figures for 16 litre units sold in South Africa show how much it varies. One datasheet gives a working water pressure of 20 to 500 kPa and an output of 3 to 16 litres a minute. Another gives 25 to 500 kPa and 4 to 16 litres a minute. A third model is listed as working from 10 kPa. Same nominal size, and the lowest pressure each will run at differs by a factor of two and a half.
Now set that against how water reaches Durban taps. Since the April 2022 floods took out two of the four Molweni aqueducts, eThekwini has rationed in published windows and throttled reservoir inlets to rebuild storage, with Northdene 3's inlet held to 15% and the reservoirs below it opening for about three hours twice a day. A shower that fires happily at six in the morning can sit below a unit's minimum at eleven, and the result is a geyser that lights, drops out and lights again, or never lights at all.
The top of the window catches people out from the other direction. Both of those datasheets stop at 500 kPa, while section 51 of eThekwini's Water By-law allows static pressure of up to 600 kPa at a tap. A supply can therefore sit inside the by-law and still above what the unit is rated for, and a main refilling after an outage can briefly spike past its static figure. Where that is possible, a pressure control valve on the geyser's inlet is part of the installation, not an optional extra.
Before you choose a gas geyser, find out your pressure at your worst hour and overnight. If the worst hour falls below a unit's minimum, pick a model rated lower, or feed the geyser from a tank and pump so it sees steady pressure whatever the street is doing. Either costs less than a geyser that only works when the rationing schedule allows.
Five things worth knowing before you choose a model.
Measured, sized, fitted to its rating and certified, in that order.
A gauge reading at the hour your supply is weakest decides which units are candidates at all.
The outlets that run together, and the temperature you want at them, set the litres a minute.
Indoor or outdoor, flued or room-sealed, exactly as the manufacturer rates that particular model.
A Certificate of Conformity for the gas side, and the water connections done by a registered plumber.
Cost first, then the pressure, sizing and siting questions that decide whether it works.
The unit is the easy number to find. What the installation costs depends on where it goes. A geyser mounted on an outside wall next to an existing gas cylinder is a short job. A new cylinder position, a gas line run across the house, a flue, and hot water pipework re-routed to a new heat source make it a long one. Labour sits inside the trade's published national guidance of R450 to R850 an hour and R450 to R650 to call out, before VAT. Get the unit, the fitting and the certificate priced separately, and check whether a pressure control valve is in the figure.
Because the flow through the geyser dropped below the point at which it stays lit, or the pressure fell far enough to starve it. A second outlet splits the water between two paths and can pull the pressure down at both. A unit that runs from 3 litres a minute rides that out better than one that needs 4, and a unit sized right at the edge of the household's demand shows it first. If it happens mostly at particular hours of the day, the supply is the cause rather than the geyser, for the reasons set out above.
Yes, and on a rationed supply it is often what makes gas worth having. A pump drawing from a tank gives the geyser steady pressure whatever the street is doing, which keeps it inside its working range. The pump has to be set so the pressure reaching the geyser stays under the unit's maximum. And because the pump needs power, the hot water now does too, which partly undoes one advantage of gas during a power cut. The tank installation page covers the pump side.
Some can and some cannot, and the datasheet decides rather than anybody's preference. Some units sold here are rated for outdoor use only and must be fitted under a weather cover. Others are built for indoor use on an external wall, with a flue that takes the combustion products outside, and room-sealed models draw their air from outside through a balanced flue so they can sit in a cupboard. A unit rated for outdoors and fitted inside is a combustion risk, and not an installation anybody should be certifying.
Size it on litres a minute at the temperature you actually want, not on the number of bathrooms. Two showers running together need roughly twice the flow of one, while a basin opened during a shower adds less. The figure on the box, 16 litres for example, is a nominal flow at a stated temperature rise, so when the incoming water is colder the usable flow at a comfortable temperature drops. Count what genuinely runs at once at the busiest moment in your house, size for that, and leave some margin.
Work it out from the datasheet rather than a rule of thumb. One published 16 litre datasheet gives a maximum gas consumption of 2.65 kg an hour, so at full output a 9 kg cylinder is a little under three and a half hours of burner time. A geyser is rarely at full output, and units that modulate burn less at lower flows, so real use stretches further than that. Add up minutes of hot water per day, not days, and the arithmetic shows whether two 9 kg cylinders or a larger installation suits the house.
Many do not. The datasheets for a number of units sold here describe battery ignition, so the geyser lights and runs with no mains power at all, which is a large part of the appeal when the power goes. Check the specific model, because some designs use a mains-powered fan or control board. And if the geyser is fed from a tank by an electric pump, the pump needs power even though the geyser does not.
It can, so read the warranty before choosing who fits the unit. At least one manufacturer's listing makes its warranty conditional on installation by a registered LP gas installer to SANS 10087-1, the standard for LP gas installations. Beyond the warranty, gas work needs a practitioner registered for gas to issue a Certificate of Conformity, which the gas installation page explains, and the water connections are plumbing work in their own right.
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Tell us how many outlets need hot water at once and where the geyser would go, and you will get the unit, the fitting and the gas certificate priced separately.