Instant or "tankless" water heaters sound like the perfect upgrade — endless hot water, no tank keeping water hot all day. They have real merits, but in South African homes the electrical reality decides whether they make sense. Here is the honest comparison.
How they differ from a geyser
A geyser stores and keeps a tank of water hot around the clock. A tankless unit heats water only as it flows, so there is no standing energy loss — but it must deliver a lot of heat instantly, which means a very high momentary power draw.
The electrical catch
A whole-house electric tankless heater can need 20–30A or more on a dedicated heavy circuit — often beyond what an existing DB board comfortably allows. That is the single biggest reason they are better suited to point-of-use rather than whole-home duty in most homes.
Where they shine
- A guest bathroom or single basin far from the main geyser
- A flat or cottage with limited space
- As a top-up at a specific point of use
The load-shedding angle
An electric tankless unit needs mains power, so it is dead during load-shedding. A gas instant heater, however, runs without electricity — an excellent option if uninterrupted on-demand hot water is the goal (see our gas vs electric comparison).
Our take
For whole-house supply, a geyser with a GeyserWise controller or solar usually wins on practicality and running cost. For a single point of use or tight space, tankless is great. We will check your electrical capacity before recommending — ask us. See also hot water systems.