Gas Geysers in South Africa: Cost, Installation and Running Cost vs Electric

How a gas geyser works

A gas geyser (strictly an instantaneous or tankless gas water heater) has a burner and a copper heat exchanger. When you open a hot tap, water flow is detected, the burner lights and the water is heated on its way through. Close the tap and the burner goes out. Nothing is stored, so there's no standing heat loss, which is the energy an electric geyser wastes keeping 150 litres hot all day.

Our guide to the five types of geyser compares gas with electric, solar, heat pump and hybrid geysers. This page goes deeper into gas alone: buying one, fitting it and what it costs to run.

The main types you'll see

Using one manufacturer's current South African range as an example, gas geysers come in four broad designs:

• Diaphragm-activated. The simplest and cheapest. Water pressure opens the gas valve. They suit one tap at a time and need decent mains pressure.
• Low-pressure or "eco-flow". Designed to light at lower water pressure, which matters in older homes, on farms or where water comes from a tank. Usually one outlet at a time.
• Constant temperature. Electronics adjust the flame to hold the water temperature steady as flow changes, so you don't get the hot-cold swings of cheaper units when someone opens another tap. Most run on batteries for ignition.
• Fan-forced (fan-assisted). A fan pushes the exhaust out through a flue. These are the larger 16L to 30L units for bigger homes and the usual choice for indoor installations. The fan needs electricity, so check how a specific model behaves during a power cut.

You'll also see indoor and outdoor versions. Outdoor models are the most common and the easiest to fit and service. An indoor model must have a flue to take the burnt gases outside and a permanent supply of fresh air for combustion.

Sizing: litres per minute, not tank size

A gas geyser's rating is the flow of hot water it can deliver while a tap runs. The manufacturer's sizing guide we checked suggests:

Flow is reduced in winter, when the incoming water is colder and the unit has to lift its temperature further. If two showers in the morning matter in your house, size up rather than down.

What a gas geyser costs to buy

There's no single "gas geyser price", because the unit is only part of the job. As one real example, these are the unit-only prices listed in Dewhot's own online shop on 20 October 2026. We use the brand only as a reference point; SolarGuide has no relationship with it.

These are unit prices only, without a weather cover, which the shop lists as an option for a few hundred rand more. On top of the unit you'll pay for:

• the gas cylinders (or a cylinder exchange deposit) and a regulator;
• copper or approved gas piping from the cylinder to the geyser;
• plumbing to connect the hot and cold water lines;
• a flue kit and ventilation for an indoor unit;
• labour, and the gas Certificate of Conformity.

We haven't quoted installation prices because they depend on pipe runs, wall type, indoor or outdoor placement and your area. Ask for a written quote that lists every item above separately, so you can compare like with like.

Installation rules you need to know

A registered gas installer, and a Certificate of Conformity

Gas installations in South Africa must follow SANS 10087-1, the national standard for LP gas installations in homes and other buildings. The work must be done by a gas practitioner registered with SAQCC Gas, the body the Department of Employment and Labour has appointed to register gas installers. A general plumber who isn't registered for gas may not do it, even if they're fitting the water side.

When the job is done, the installer issues a gas Certificate of Conformity (CoC) confirming that the installation is safe, leak-free and compliant. Keep it. It is commonly asked for in insurance claims and when you sell the house. You can check an installer's registration on the SAQCC Gas website by name, company or registration number before you book.

Where the geyser and cylinders can go

The installer will place the unit and cylinders to meet SANS 10087-1. In practice:

• Outdoor units go on an outside wall, normally under a cover, with the cylinders outside and set away from doors, windows, drains, air vents and electrical switches by the distances the standard sets.
• Indoor units need a flue to take exhaust gases outside and a permanent supply of fresh air. Never fit an outdoor-only model indoors, and never block a flue or vent.
• Cylinders normally go outside on a firm, level base, upright and secured, where the gas can't collect in a low, enclosed space. LPG is heavier than air.

Every gas appliance produces exhaust gases, including carbon monoxide if combustion is poor. That's why the flue and ventilation rules exist and why a qualified installer matters. If an indoor gas geyser is part of your plan, a carbon monoxide alarm nearby is a sensible extra.

Water pressure

Check the unit's minimum water pressure against your supply. The 12L outdoor constant-temperature model in the table above, for example, needs at least 25kPa to operate. A low-pressure home may need a low-pressure model or a different setup altogether.

The running cost: gas vs electric, worked out

This is the part most guides skip. Here is the calculation, with every assumption shown, so you can redo it with your own numbers.

Step 1: the price of the energy

LPG. The Department of Mineral and Petroleum Resources sets a maximum retail price for LPG sold to homes each month. From 7 October 2026 it is R37.81/kg in Gauteng and R34.56/kg on the coast, with LPG imported through Saldanha Bay capped at R37.08/kg in the Western Cape. At those prices a 9kg refill can cost up to about R340 inland. LPG weighs about 0.51kg per litre, so the inland cap works out to roughly R19 per litre if your supplier sells by volume.

Electricity. We use Eskom's Homelight 60A rate for 2026/27: 343.61c/kWh including VAT, a single price with no fixed charge. Municipal rates differ, and many use rising blocks. Check the energy charge on your own bill or your municipality's tariff schedule and substitute it.

Step 2: how much heat you get from each

• 1kg of LPG contains about 12.9kWh of usable energy (its net calorific value, per the UK's Forest Research fuel table). The gas geyser we checked lists an efficiency of 84%, so each kilogram puts about 10.8kWh of heat into your water.
• 1kWh of electricity through an element puts close to 1kWh into the water. But a storage geyser also loses heat standing around. Under SANS 151, a modern Class B 150L geyser may lose up to 1.40kWh a day, according to Kwikot's geyser guide. Older units were allowed 2.59kWh.

So at the inland price, gas heat costs about R3.49 per kWh delivered to the water (R37.81 ÷ 10.8). Element heat costs R3.44 per kWh before standing losses, and more once you add them.

Step 3: a real household

Take two adults using 80 litres of hot water each a day, the per-adult figure Eskom uses, heated from 20°C to 60°C. That needs about 7.4kWh of heat a day, or 226kWh a month.

Electric geyserR924

Gas, inlandR790

Gas, coastalR722

Heat pump, mid caseR369

These are SolarGuide calculations, not measured bills. They leave out cylinder rental or delivery fees, heat lost in long pipe runs, and the lower efficiency some gas units have at low flow. The heat pump range comes from South African field measurements, which our heat pump geyser guide explains.

What the numbers tell you

• Gas is roughly level with electric on running cost. It saves a little because there's no standing loss. Against an older, poorly insulated geyser the saving is bigger. Against a well-run electric geyser on a timer it may be close to nothing.
• The break-even is easy to find. With these assumptions, gas beats the electric geyser per unit of hot water as long as LPG costs less than about R44/kg. Ignore standing losses and the break-even drops to about R37/kg, almost exactly today's inland price.
• Gas prices move monthly; electricity moves yearly. LPG follows international prices and the rand exchange rate, so the comparison can swing either way through the year.

Our geyser cost calculator works out your current electric geyser's cost from your own household size, tank and tariff.

Pros and cons of a gas geyser

What gas does well

• Hot water with no grid at all. Battery-ignition models keep working through load-shedding and local outages.
• Endless hot water while the gas lasts, with no tank to run cold after the third shower.
• No standing losses, because nothing is kept hot when you're not using it.
• A relatively low unit price compared with a heat pump or solar water heater.
• Fits where a big tank can't, such as flats with landlord approval for an outdoor unit, cottages and holiday homes.

What to weigh against it

• Running cost close to electric, at today's prices, and well above a heat pump or solar.
• Refills to manage, cylinders to store outside and an LPG price that changes every month.
• Flow limits: a small unit struggles with two showers at once, and winter reduces output.
• Strict installation rules, a registered installer and a CoC, plus a flue for indoor units.
• Some fan-forced and electronically controlled models need mains power.

When solar PV with a heat pump or a timer beats gas

If your aim is a lower bill rather than hot water during outages, gas usually isn't the strongest option. Three alternatives tend to win on running cost:

1. A timer on your existing geyser. The cheapest step. Heating only before the morning and evening use cuts standing losses and costs very little to set up. It doesn't change the price per kWh, but it trims the 1.4 to 2.6kWh a day the tank wastes.
2. A heat pump. In our example it costs about R310 to R440 a month against gas at R720 to R790. It still uses electricity, so it won't heat during an outage on its own.
3. Solar PV that heats the water in the day. If you're installing solar panels anyway, a heat pump or a timed element can run in the middle of the day on your own generation. Our comparison of a solar geyser and solar PV explains how water heating fits into a PV design.

Gas still makes sense alongside these. Plenty of homes use gas for the stove and as a backup heater for a solar water system, while panels and a battery run the rest of the house. Our gas vs solar vs battery guide covers that split.

If your hot water and electricity bill are both on your mind, it's worth seeing what a solar system that also takes care of daytime water heating would look like. Compare solar options for your home →

A quick way to decide

• You want hot water that never depends on Eskom or the municipality: a gas geyser, fitted properly with a CoC.
• You want the lowest monthly water-heating cost and keep your current tank: a heat pump retrofit, or a timer as a first step.
• You're planning solar panels anyway: design the water heating into the PV system from the start, and mention how you heat water when you ask for a quote.
• Your geyser has just burst: compare the replacement cost of each option side by side before you sign, because this is the cheapest moment to switch technology.

Frequently asked questions

Is a gas geyser cheaper to run than an electric geyser?

Only slightly, at October 2026 prices. In our worked example for two adults, gas costs about R720 to R790 a month and a modern electric geyser on Eskom's Homelight 60A rate about R920. Gas saves mainly because it has no standing losses. Against an older geyser the saving is bigger; against a geyser on a well-set timer it shrinks. A heat pump costs far less to run than either.

How much LPG does a gas geyser use?

It depends on how much hot water you use. Heating 160 litres a day from 20°C to 60°C takes about 0.7kg of LPG a day with an 84%-efficient unit, or roughly 21kg a month, a little over two 9kg cylinders. A household that uses more hot water, or has colder incoming water, will use more.

Can I install a gas geyser myself?

No. Gas installations must comply with SANS 10087-1 and be done by a gas practitioner registered with SAQCC Gas, who issues a Certificate of Conformity. Insurers and buyers commonly ask for that certificate, and a DIY installation puts you, your household and your insurance at risk.

Can a gas geyser go inside the house?

Only an indoor-rated model, installed with a flue that takes the exhaust gases outside and a permanent supply of fresh air. Outdoor-only models must stay outdoors, and the cylinders for a geyser are normally installed outside. Your installer will position both to meet the standard.

Is SolarGuide the installer?

No. SolarGuide is an independent referral partner for solar PV systems, which Alumo supplies, installs, finances and warrants. We don't sell or install gas geysers, so use an SAQCC Gas registered installer for that work. We can help you compare solar options and get a free quote. All pricing is indicative and subject to a site assessment and credit approval.

Sources and review note

Checked on 20 October 2026. LPG maximum retail prices effective 7 October 2026 come from the Fuels Industry Association price table (Gauteng and coastal) and the Minister's 5 October 2026 fuel price statement (Saldanha Bay). The electricity rate is Eskom's Homelight 60A energy charge from the 2026/27 Schedule of Standard Prices, Table 14. LPG energy content and density are from Forest Research's typical calorific values table. Unit prices, sizing guidance, the 84% efficiency and the 25kPa minimum pressure come from Dewhot's online shop, sizing guide and 12L product page; these are manufacturer listings and claims, not SolarGuide tests. Standing-loss limits are as summarised in Kwikot's electric geyser guide. Installer registration is from SAQCC Gas. Monthly costs and the break-even prices are SolarGuide calculations from the stated assumptions. LPG prices change on the first Wednesday of each month, so swap in the current price per kilogram to update the comparison.