A Heater Sized For The House
Chosen in litres per minute for the outlets it has to run at once, and checked against the water pressure measured at the house.
Home/Gas Geyser Installation
Gas geyser installation in Bellville pays off when you know where the saving comes from. Per unit of heat, LP gas costs about the same as the City's first electricity block, so most of the saving is the hot tank you stop keeping. Every part of the installation is itemised before work starts.
Tell us whether the gas geyser is replacing an electric one, and where the heater and the cylinders could go.
The heater is one item on a longer list. Each of these is checked against the standard and the manufacturer's manual before the certificate is signed.
Chosen in litres per minute for the outlets it has to run at once, and checked against the water pressure measured at the house.
An outdoor model on an outside wall, or a flued or room-sealed model indoors, positioned the way its type and manual allow.
Cylinder position, regulator and changeover set out on site, with a lockable cage where the cylinders stand in reach of the street.
A rigid gas supply from the regulator to the appliance, an isolating valve beside the heater, and every joint leak tested.
Cold feed and hot outlets reconnected, and the old electric geyser drained and removed or isolated, as agreed in the quote.
Issued on completion by the registered installer who did the work, for the heater, the cylinders and the line between them.
The City of Cape Town says a geyser is typically responsible for 40 to 60% of an average home's electricity costs. Whether gas brings that down depends on two numbers: what a unit of heat costs from each source, and how much electricity an electric geyser spends just keeping its tank hot.
Start with the heat. Bosch's 14-litre Therm 4300 burns 2.2 kg of LP gas an hour for 23.6 kW of output, which is about 10.7 kWh of heat per kilogram. The Western Cape's maximum retail price for LP gas from 7 October 2026 is R37.08 per kg, so a kWh of heat from gas costs about R3.46. On the City's 2026/27 Home User tariff, a kWh of electricity costs R3.56 for the first 600 kWh in a month and R4.69 above that, VAT included.
Unit for unit, then, gas is level with the City's first block and cheaper than its second. A house that stays under 600 kWh a month saves very little on the heating itself. One that regularly goes over pays R4.69 for every unit above 600, and hot water moved to gas comes off that top block first.
The bigger difference is the tank. An electric geyser keeps its water hot around the clock and loses heat through its casing whether anyone opens a tap or not. The standard a new geyser has had to meet since August 2017 allows a 150-litre geyser to lose up to 1.38 kWh a day on test, and the limit before that was 2.59 kWh. An instantaneous gas heater stores no hot water, so that loss goes. At R3.56 a unit, the newer limit is worth about R150 a month and the older one about R280.
Gas makes the strongest case in a home with an older electric geyser, a large household, or a bill that regularly passes 600 kWh. In a small household on the first block, the heat costs about the same either way and the saving is mainly the tank. Look at three months of electricity bills before you decide.
A gas geyser joins a gas installation and a water installation in one appliance. Both halves are finished before it is lit.
The installer's SAQCC Gas card, with its scope and expiry date, is shown before work starts.
Measured at the house before a model is chosen, so the heater lights at the outlet furthest from it.
Every gas joint leak tested under pressure, then the burner checked running and the controls explained.
The Certificate of Conformity is issued through SAQCC Gas's digital system and sent to you on completion.
It depends mostly on the heater's size, whether cylinders, a regulator and a cage are needed or already there, the length of the gas line, the flue, and what changes on the water side, including removing the old electric geyser. Each is a separate line in the quote before work starts. How quotes are built is on the plumber prices page.
Usually, but by less than people expect on the heat itself. At October 2026 prices, LP gas works out to about R3.46 per kWh of heat. The City charges Home User customers R3.56 per kWh up to 600 kWh a month and R4.69 above that, and prepaid homes on the Domestic tariff pay R4.14 and R4.94. The larger saving is the standing loss of the electric tank, which a tankless heater does not have.
At full output, Bosch's 11-litre Therm 4300 burns 1.75 kg an hour, so 9 kg gives a little over five hours of flame. Showers rarely run a heater flat out. As a worked example, an eight-minute shower at the City's 7-litre-a-minute showerhead limit, warmed by 25°C, needs about 1.6 kWh of heat, or 0.15 kg of gas, so 9 kg covers close to 60 such showers. Basins, baths and the kitchen draw on the same bottle.
Gas geysers are sized in litres per minute, not in tank litres, so the question is how many hot outlets run at the same moment. In Cape Town a showerhead may deliver no more than 7 litres a minute, and part of that is cold water, so two people who shower one after the other need less than the head count suggests. Two showers at once, or a bath filling while someone showers, need a larger unit and the water pressure to light it at both.
It needs a minimum water pressure and flow to light, which an upstairs bathroom can struggle to reach. The cylinders need a compliant position, space and regular refills. Where the heater can go is limited by its flue type, and the installation needs a Certificate of Conformity, and a new one when the house is sold. Some models also need mains power to run.
It depends on the model. Bosch's Therm 4200 lights from two 1.5 V batteries, and its Therm 4300 makes its own ignition from the water flowing through it, so neither needs mains power. Some fan-assisted models need a 220 to 240 V supply and stop when the power does. If hot water during outages matters to you, say so before the model is chosen.
Yes, if it is a type made for indoors and the room suits it. Outdoor models stay outside. Indoors, the heater is either flued to the outside or room-sealed, with the ventilation its manual and the standard require, and SANS 10252-1 rules out a flueless heater for a shower or bath. The position is settled on site against the current edition of SANS 10087-1.
No. The Pressure Equipment Regulations allow only an authorised person, in practice an installer registered with SAQCC Gas for that scope, to install a gas appliance, and the City's Water By-law reserves replacing a fixed water heater for a qualified, accredited person. Without the Certificate of Conformity, an insurer can also refuse a claim involving the installation.
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Swapping an electric geyser for gas, or adding gas hot water to a new room? Describe the house and where the heater could go, and we will come back with a price.