Electric shower - testing and replacing the heating tank element in the heat exchanger

Bit harder to do compared to other jobs but nothing that you cannot do , to test the element use a multimeter set to resistance Omhs scale and test both elements as below my reading were 15 Ohms for one and 12ohms for the other this is normal and good readings for an electric shower heater element . if you get OL it means an element it damaged internally and 0.00 mean short circuit but this would blow you main fuse.

To check readings you have to calculate parallel  resistance of the 2 elements which in this case is 6.67ohms then the formula is V squared / resistance 

So 57600 / 6.67 = 8635.6 / 1000 = 8.6KW this is an 8.5kw so good enough 

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First remove the outlet pipe retaining screws 

and the side retaining screw of the heater can 

then flip it around you can test the element now while in shower or out after 

depends on circumstances 

Just resistance read both heating elements here i have 12 ohm 

and 15 ohms 

Check your measurements its quite easy to tell what your measures are meant to be

Voltage / resistance = Power 230V / ( 12 + 15 ) = 8.5KW 

then undo the neutrals side of element 

Next undo both brown wires to element Lives , and ensure you know which is top and bottom

next i undo screw holding thermal cut out it place 

and pull the cut out free of heater to allow me to pull heater out

when you replace do not forget o-ring 

testing heater out of the shower 

place it back carefully make sure all o-rings are fitted and seal

and all wires are correct and tight 

see video of the whole process below