Answer: With the information you provided, we can only take a shotgun approach in an attempt to help you.
If you are positive that the electric water heater has power, then the problem must reside with the heating element or an internal connection, fuse or reset button between the heating element and the power supply.
So, assuming that you have checked that you have 120 volts at the water heater and checked the associated circuit breaker for power then you will have to take the following steps.
Bad Heating Element:
- Find your owners manual and determine the model number of the replacement heater element and anode if it has one.
- Read about the steps needed to replace the element and anode (if equipped), ie., draining and yearly maintenance etc.,
- Turn off power to the electric water heater
- Shut off fresh water supply and turn on any hot water faucet to relieve water pressure – If you are lucky enough to have a water shut off on the inlet side of the hot water heater shut that off also
- Release pressure from the electric water heater (via the pressure relief valve)
- Drain water heater – if you have a drain set up good if not screw in a garden hose to the drain valve at the bottom of the water heater and open the valve to drain
- Remove the old element and anode following your manufacturer recommendations
- Install the new heating element and anode if equipped following your manufacturer recommendations
- Refill the water heater with fresh water make sure to bleed off any trapped air in the water heater – Open a hot water tap until no air comes out of that tap. This step is critical to prevent the heating element from being exposed to air and burning out.
- When you are sure that no air is in the water tank turn the power back on to the water heater and wait for the hot water.
Our hot water heater (8 gallons) takes about 45 minutes to fully heat cold water.
If it is not your electric heating element, then you should check for power at the terminals that supply power to the element. The terminals are usually behind on access panel. If you have power at the circuit breaker but no power at the electric element terminals then you many need to push a reset button, replace an internal fuse, fix some internal wiring, replace the water heater or take the RV to a repair facility to get the problem identified and fixed. But before you take it to a repair facility check with the manufacturer, they may be able to help.
By the way some 120 volt water heaters have a 12 volt relay that controls the element and will not provide 120 volts to the element unless the relay is working and has 12 volts – again check with your manufacturer.
You did not specify if the water heater was hard wired or plugged into an outlet. If it plugs into an outlet verify that you have 120 volts at the outlet and that the cord is working properly.
Please let us know how you resolved your issue so others can learn from your experience.