Replacing your immersion heater

3rd Feb 2020

How to change the immersion heater

  • Turn the electricity to the immersion off and remove any fuses just in case. Remove all the wires and make a note of live, neutral and earth.
  • Find the cold water supply to the hot water tank and turn it off. Sometimes you will have to go up in the loft and drain the supply tank.

  • Run the hot water taps until the water stops. Sometimes this can take 10 minutes or more. Although the tank is still not drained now is the time to loosen the immersion heater. The water still inside the immersion tank stabilises the thin copper wall from the pressure you apply to remove the heater. After this close the cold water supply valve to the tank.
  • Identify the drain point at the bottom of the tank and using a hose, drain the tank.

  • When the tank is drained, unwind the immersion heater.
  • Insert the new heater, careful not to cross the thread. Tighten but not too much.

  • Turn off the drain point and taps. Re-fill the tank. Test for leaks.

  • Re-install the electrical connections and set the thermostat in the immersion to the desired temperature. Replace cover, any fuses and turn on the power. After 30 minutes turn on the hot tap, you should notice warm water coming through.... It may take a few hours before you get really hot water.
  • We always recommend having your electrics certified by an electrician. 

Find replacement immersion heaters at FixTheBog