Open the pilot light panel on the hot-water heater. Turn on the gas at the tank by turning the valve to the open position. While working on the pilot light, check the water heater's vents for any debris or excessive dust build-up. Clean out the vents so there is a free flow of air in and out.
Spark your lighter and hold the flame at the small gas nozzle tube inside the panel. Watch for any blue flame ignition after holding the lighter to the pilot tube. If no flame is present. Turn off the gas at the tank and disconnect the gas hose off the tank.
Unscrew the pilot tube in the panel and push the pipe cleaner through the tube several times. Brush away any debris or sediment from the tube, and screw it back into position. Attach the gas hose to the tank and turn the gas on.
Spark the lighter and hold it to the pilot tube to ignite the pilot flame.
Inspect the seals around the tank as you address the pilot-light issues. Look for any dripping or seepage not caused by condensation. Use the waterproof caulking to re-seal the heater tank if there is dry rot, cracking and leaking.
Drain the hot water heater tank completely. Take the RV to a dump station to drain if needed. Just like with a gas heater, inspect the tank's seals for dry rot and cracking. Seal the leaks with the water-proof caulking.
Turn off all electric connections and switch the main circuit breaker to the off position. Check the heater's air vents for dust and corrosion build-up. Clean out the vents to allow free flow of air in and out.
Open the water heater panel and find the heating element coil--consult your RV owner's guide if unsure of the exact location.
Unscrew the coil with the adjustable wrench and remove.
Screw in the new heating coil/element. Close the panel and fill the water heater tank with water. Flip the circuit breaker back to on and connect the electricity. Turn the water heater on and adjust the temperature dial to your desired setting.