The thermostat controls when the geyser element switches on and off. A faulty or poorly set thermostat can leave water cold, cause overheating, increase electricity use or repeatedly trip the system. Because the thermostat is part of the electrical circuit, testing must be done safely.
Before you worry
Temperature can also be affected by a failed element, mixing valve, pipe losses or unusually high demand. Note whether the problem is constant and whether the water is dangerously hot.
How to recognise the problem
- Water is consistently too hot or too cold.
- The geyser heats only intermittently.
- The reset trips repeatedly.
- Electricity trips during heating.
- The geyser runs for unusually long periods.
Common causes
- Worn thermostat contacts.
- Incorrect temperature setting.
- Poor contact with the cylinder pocket.
- Scale or overheating damage.
- Loose or damaged wiring.
- A separate element fault.
What you can safely check yourself
- Avoid using scalding hot water.
- Switch off the geyser circuit if overheating is suspected.
- Note whether the issue occurs at all outlets.
- Do not remove the electrical cover.
What you should never do
- Do not bypass the thermostat.
- Do not increase the temperature to compensate for another fault.
- Do not work on live wiring.
- Do not repeatedly reset a tripping safety device.
When to call a plumber
Professional help is needed when water is dangerously hot, the geyser does not heat, the reset trips, or the electrical supply trips. These symptoms can involve both plumbing and electrical safety.
How professionals solve it
The circuit is isolated and the thermostat, element and wiring are tested. The correct thermostat is fitted and positioned properly, then the system is monitored through a heating cycle to confirm safe cut-off and stable temperature.
How to prevent it happening again
- Use appropriate temperature settings.
- Address scale and element problems.
- Keep electrical covers secure and dry.
- Investigate repeated resets promptly.
- Use compatible replacement parts.
Frequently asked questions
What temperature should a geyser thermostat be set to?
The appropriate setting depends on safety, hygiene and system design. A qualified professional can confirm a suitable setting for the installation.
Can a thermostat cause high electricity use?
Yes. If it fails to switch off correctly, the geyser may heat longer than necessary.
Why does the thermostat reset keep tripping?
Overheating, a faulty thermostat, element problems or wiring defects may be responsible.
Need help with a geyser problem?
Tell us what you have noticed, whether water is leaking or electricity is tripping, and the approximate age of the geyser so we can help arrange the right response.