Geyser Size Calculator — South Africa
Calculate the correct geyser capacity for your household based on SANS 10106 guidelines. Compares running costs for electric, heat pump and solar geysers.
Quick answer: The SANS 10106 rule of thumb is 50 litres per person for standard household usage, so a family of 4 needs a 200-litre geyser. High-usage households with double showers or bathtubs should increase to 60–70 litres per person. Heat pump geysers have a slower recovery rate for the same capacity.
⚠️ For planning purposes only. All geyser installations in SA must be done by a registered plumber. A Compliance Certificate is required under SANS 10106 and SANS 10252.
How to Use This Calculator
Enter the number of occupants and select a usage profile — Medium (50L/person) is the SANS 10106 default. Choose your geyser type: electric is cheapest to buy, heat pump and solar cost more upfront but far less to run.
Enter your electricity tariff (check your municipal bill) and calculate. Results show the recommended capacity, element size, recovery time, and a running-cost comparison across all three geyser types for your household.
Geyser Sizing in South Africa — SANS 10106
The water heating system is typically the single largest electricity consumer in a South African home — accounting for 30–40% of the total electricity bill. Selecting the right geyser size and type is one of the highest-impact decisions a homeowner or property investor can make for energy efficiency and running cost reduction.
SANS 10106 (Code of Practice for the Installation of Domestic Hot Water Storage Systems) sets the standard for geyser sizing, installation, and safety requirements in South Africa. The base calculation is simple: 50 litres of stored hot water per person per day for medium usage. This ensures the geyser can meet peak morning demand without running cold before everyone has showered.
Standard Geyser Sizes Available in South Africa
| Capacity | Occupants | Element | Recovery Time | Approx Price (2026) |
|---|---|---|---|---|
| 100L | 1–2 people | 2kW | ~2.5h | R1,800–R3,500 |
| 150L | 2–3 people | 3kW | ~2.5h | R2,200–R4,500 |
| 200L | 3–4 people | 3kW–4kW | ~3h | R2,800–R5,500 |
| 250L | 4–5 people | 4kW | ~3h | R3,500–R7,000 |
| 300L | 5–6 people | 4kW | ~3.5h | R4,500–R9,000 |
Electric vs Heat Pump vs Solar Geyser
South Africa's load shedding environment and high electricity tariffs have made geyser type selection more important than ever. Here is the practical comparison for SA conditions:
- Electric resistance geyser: Cheapest to install (R2,000–R5,000 + installation). 100% efficient — converts all electricity to heat. Most affected by load shedding. Highest running cost.
- Heat pump geyser: Higher purchase cost (R8,000–R20,000 + installation) but 60–70% cheaper to run. COP of 2.5–3.5 — produces 2.5–3.5 kWh of heat per kWh of electricity. Continues working during load shedding if powered by inverter/battery. Highly effective in SA's warm climate year-round.
- Solar geyser (thermosiphon or flat plate): Uses the sun directly to heat water. No electricity for heating in sunny weather. Requires electric backup element for cloudy days and winter. Pays back in 3–5 years in most SA locations. Not affected by load shedding for daytime use.
Geyser Placement and Installation Requirements
SANS 10106 specifies that electric geysers must be installed in an accessible location with adequate clearance for maintenance, fitted with a drip tray and drain pipe, and connected to a dedicated circuit with the correct breaker rating. Most South African municipalities and insurers require a drip tray with an overflow pipe draining to outside the building — an overflowing geyser without a tray causes ceiling and structural damage that is not always covered by home insurance if the tray was absent. All geyser installations must be certified by a registered plumber who issues a Certificate of Compliance (CoC).
Geyser placement affects energy consumption significantly. A geyser installed close to the most-used hot water points loses less heat in the pipe run between the geyser and the outlet. Long pipe runs mean the hot water standing in the pipe cools between uses, wasting the energy used to heat it. Locating the geyser centrally between the major hot water points reduces standing losses meaningfully over the installation's lifetime.
Geyser Timers and Smart Controllers
A geyser timer is one of the lowest-cost energy-saving devices for South African homeowners, with payback periods under 12 months in most cases. A basic mechanical timer costs R200–R500 and restricts heating to off-peak hours. Smart geyser controllers (R800–R2,500) allow remote control, load shedding scheduling, and solar integration. For households on time-of-use tariffs, restricting geyser operation to off-peak hours produces the largest savings. A geyser blanket (R200–R500) reduces standing heat losses by up to 30% on older uninsulated geysers and is one of the simplest energy-saving retrofits available. Newer geysers manufactured after approximately 2015 are factory-insulated to SANS standards and do not benefit significantly from an additional blanket. If your geyser is less than 10 years old, the blanket is unlikely to pay back its cost. On an older, uninsulated geyser — identified by a warm or hot exterior casing — the blanket is one of the highest return-on-investment energy interventions available to South African homeowners. SANS 10106 (the South African standard governing domestic electric water heating) requires that geyser thermostats be set to a minimum of 55°C to prevent Legionella growth and a maximum of 70°C for safety — factory default of 65°C is SANS compliant. Heat pump geysers operating at SANS-compliant temperatures produce water at 55–60°C using 60–70% less electricity than a standard element geyser, making them the most energy-efficient option for households with consistent hot water demand above 200 litres per day.