Electric water heater is a commonly used household electrical appliance. The major types of electric water heaters available in the market include instantaneous, shower type (also known as low-pressure storage type or open type) and unvented thermal storage type (also known as high-pressure storage type). Although electric water heaters in the market are provided with appropriate safety devices, incidents involving electric water heaters occurred occasionally in the past. Investigations revealed that the main causes of the incidents were mainly improper installation and lack of maintenance.

The public should note the following when using the electric water heater:

 

Should

  • Employ registered electrical contractors and licensed plumbers for installation or modification of electric water heaters.
  • Adhere to the instructions given in user manual of an electric water heater.
  • Picture 1: Switch off the power source of an electric water heater after useSwitch off the power source of an electric water heater after use.


  • Arrange an experienced technician to inspect and maintain an electric water heater regularly.
  • Picture 2: If an electric water heater has an abnormality while in use (such as circuit breaker tripping), stop using it immediately and contact the supplier for inspection and repair If an electric water heater has an abnormality while in use (such as circuit breaker tripping), stop using it immediately and contact the supplier for inspection and repair.

 
 

Should Not

  • Ensure that shower head with on/off valve is not installed for "Shower Type" electric water heater to prevent excessive pressure from building up inside the water storage tank, causing an explosion.

    Picture 3: Ensure that shower head with on/off valve is not installed for "Shower Type" electric water heater to prevent excessive pressure from building up inside the water storage tank, causing an explosion

 

Trade members should note the following during installation or modification and maintenance of an electric water heater:

 
  • The installation or modification of an electric water heater must be carried out by a registered electrical contractor and a licensed plumber.
  • The vent pipe of vented storage type electric heater must not be installed with any on/off control valve to avoid damage the safety design of the electric water heater.
  • The outlet pipework of a shower type electric water heater must not be connected with any on/off control valve and must not be connected to basin or bath tub, to prevent excessive pressure from building up inside the water storage tank, casing an explosion.

    Picture 4: The outlet pipework of a shower type electric water heater must not be connected with any on/off control valve and must not be connected to basin or bath tub, to prevent excessive pressure from building up inside the water storage tank, casing an explosion Picture 4: The outlet pipework of a shower type electric water heater must not be connected with any on/off control valve and must not be connected to basin or bath tub, to prevent excessive pressure from building up inside the water storage tank, casing an explosion Picture 4: The outlet pipework of a shower type electric water heater must not be connected with any on/off control valve and must not be connected to basin or bath tub, to prevent excessive pressure from building up inside the water storage tank, casing an explosion

  • The manufacturer’s instructions should be followed to carry out maintenance work on an electric water heater. Advice should be sought from related agent or manufacturer if necessary.
  • In case the outlet pipework or ben pipe (if any) is not properly installed, the trade member should advise the user to fix the problem immediately.
 

More safety tips for electric water heater could refer to the following:

Enquiries about the safety of electrical products should be addressed to enquires hotline (Tel. No.: 1823) or email: info@emsd.gov.hk.