If only we knew what machine you have we could advise ! It is wrong to assume the heater is faulty when dishwashers do not heat ,there are a lot of monitoring and switching components that can prevent the heater from operating. 9 times out of 10 "no heat" is not the element being faulty. Its best you give us the make and model as there are common faults for certain makes.
Kenjo
June 2014