If you’re on the move, a 24v DC water heater is a good choice. They can also be connected to batteries or solar panels for power. They are great for RVs, livestock tanks, or even to convert an AC water heater to run on DC power. To avoid heating the water, ensure that your unit has a thermostat. To replace a gas hot-water heater, make sure you get a 24-volt dc water heater.