The difficulty of repairing a water heater varies based the component that has failed, but gas water heaters typically have more parts that can break, which makes diagnosing the problem more difficult. However, wiring problems on electric water heaters can pose difficulties for the inexperienced.
Many problems on gas water heaters occur because of failed combustion. Repairs require first determining if the unit is receiving gas and then checking if the combustion components are operating correctly. Electrical systems are typically a bit simpler; if the heating element doesn't warm, it or the wires connecting to it are faulty. Gas water heaters also require ventilation, and problems with the exhaust system can trigger safeguards that prevent unsafe operation.