How to Set a Geyser Timer (Save Up to 30% on Your Electricity Bill)
24 May 2026 · Plumbers On Duty
Quick answer
A geyser timer switches your geyser on for the hours you actually use hot water and off for the rest. For most homes, 4–6 hours per day is enough to keep the tank hot. The cheapest mechanical timers cost R150 and pay for themselves in 1–2 months.
Two types of timers
1. Mechanical timer (R150–R350)
A clock-face dial fitted at the DB board. You push pins in for "on" and leave them out for "off". 24-hour cycle, repeats daily.
2. Smart timer / Geyserwise (R800–R2,500)
Programmable, app-controlled. Sets different schedules for weekdays vs weekends, can sense water temperature, integrates with solar PV.
Recommended schedule for a 150L geyser
| Household | Morning slot | Evening slot |
|---|---|---|
| Single / couple, morning showers | 5am–7am | — |
| Couple, morning + evening showers | 5am–7am | 6pm–8pm |
| Family of 4 | 5am–8am | 5pm–8pm |
| Family of 4 + bath in evening | 5am–8am | 4pm–9pm |
The tank holds heat well for 4–6 hours after the element switches off, so the water is still hot when you need it next.
How to set a mechanical timer
- Switch off the geyser at the DB before you start
- Mount the timer in the DB board between the breaker and the geyser circuit — this is electrical work; if you are not comfortable, call a sparky (R450–R800 fit)
- Set the current time by rotating the dial to the arrow
- Push the pins IN for hours you want power on, leave OUT for off
- Set the toggle to "Timer" (not "On" or "Off" override)
- Switch the geyser breaker back on
How to set a Geyserwise / smart controller
These vary by model, but the basic flow is:
- Install the control unit (in the DB) and the in-roof temperature sensor (mounted to the geyser)
- Connect via app (Wi-Fi)
- Set your preferred minimum temperature (60°C is the SA standard)
- Set your weekday and weekend schedules
- Enable boost mode for unexpected hot water needs
How much you'll actually save
- Old, uninsulated geyser: 25–35% saving
- Modern, insulated geyser: 10–20% saving
- Combined with a geyser blanket: add another 5–10%
For an average 150L geyser using ~R600/month electricity, that is R60–R200 saved every month.
Loadshedding tip
During Stage 4+ loadshedding, set the timer so the geyser is NOT scheduled to come on the moment power returns. This prevents your geyser from joining the surge that destabilises the area.
Need it installed?
Most plumbers and electricians install timers. Budget R450–R800 labour on top of the timer itself.