If you don't know what you are doing, maybe best to call a pro...
There was a homeowner who had a low wattage water heater which worked fine
on a 240V 15 amp breaker. Then one day a heating element went out...
The homeowner replaced the heating element, except purchased a higher
wattage heating element (wrong element). Then when the heating element was
installed the breaker kept tripping.
So the homeowner purchased a new water heater and this new water heater was
a higher wattage then the old water heater. The breaker again kept tripping.
Then the homeowner replaced the circuit breaker with a new 15 amp (double
throw) breaker. Same problem. Homeowner kept turning on the breaker to try
to get the water heater to work...
Then with the wires to the water heater disconnected and the breaker turned
on, there was no voltage to the wires. Seems the wiring was "fried"!
In the end the homeowner had to pay for an electrician to install new higher
amperage wiring and a higher amperage breaker, plus had the cost of the new
heating element, the new water heater, and the new 15 amp circuit breaker.
All of this could of been avoided if the homeowner had replaced the heating
element with the correct wattage element!