Hot water cylinder boils

Cause

Thermostat setting is too high

Repair

  • reset the thermostat to 60°C. Stored hot water should reach no less than 60°C at least once per day to avoid the growth of Legionella bacteria. However, the delivery temperature of hot water to sanitary fixtures used for personal hygiene such as baths, showers and hand basins must be no more than 55°C

Cause

Faulty thermostat

Repair

  • turn the cylinder off

  • homeowners are permitted to remove and replace a water heater thermostat so long as it does not involve work on a switchboard. (The details are in the Electricity Act 1992 sections 79 and 80, and NZECP 51:2004 New Zealand Electrical Code of Practice for Homeowner/Occupier’s Electrical Wiring Work in Domestic Installations.) Landlords/ business owners cannot carry out electrical work in their rental properties or workplaces unless they hold the relevant licence

  • homeowners should only make this repair themselves if they have the skills, experience and tools to be able to safely and competently complete the job. You are required by law to carry out the work “in a workmanlike manner” and in compliance with all the relevant laws and codes
    • most homeowners should call a licensed plumber to replace a faulty thermostat

Cause

Solar panel providing too much boost

Repair

  • turn the cylinder off

  • if you know the registered tradesperson who installed the system, ask them back to make the repair, especially if a proprietary system was installed. Some product warranties require all repairs to be carried out by accredited service agents