Installing a Rinnai electric water heater can cost a few hundred dollars or as much as $1,000, depending on the model you choose. Indoor condensing units and outdoor heaters are cheaper to install, but require additional gas line, while indoor models with recirculating accessories are more expensive to install. You can rest assured that your Rinnai water heater will last a long time with proper care and maintenance. Whirlpool. If you experience problems with your Whirlpool electric water heater, follow these steps to solve the problem. You should turn on the power supply to the water heater. The problem could be a blown fuse or breaker. The control panel might need to be replaced. The water temperature is over the maximum temperature set by the thermostat. Another problem could be a misplaced element or faulty insulation. If these problems do not happen, check the water heater's thermostat setting or replace it.