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Replacing Your RV Water Heater

by Staff Ashley and Brittany 1 year ago

With it getting close to winter time our RV pipes are a bit more sensitive and your water heater will run just a little harder. Sometimes, no matter how much care you put into it, accidents happen. An RV water heater can damage and burst in extreme temperatures. If you want to try your hand at replacing it yourself, let us help you with a guide on how to do just that.


Let’s start removing the old aluminum tank water heater. 


  1. Turn the LP gas supply off at the cylinders or tank. 

  2. Turn any water supply going to the RV off and make sure the Dometic water heater is in the bypass mode. 

  3. Using a pair of pliers, loosen and remove the water lines from the brass or plastic inlet and outlet fittings on the back of the water heater tank.

  4. Use two wrenches to loosen and separate the LP gas inlet connection. 

  5. Remove the hinge clip and remove the door to improve access to the screws on the control housing mounting flange. 

  6. Remove excess silicone as required to slip the inlet gas connection out of the control panel. Prior to pushing the inlet connection through the control housing opening, make sure a male 3/8th inch plug is threaded into the 3/8th inch flare gas connection.

  7. Remove all screws from the control housing mounting flange. 

  8. Remove any silicone from the top of the water heater. 

  9. Bend the control housing mounting flange 90 degrees forward and start removing the water heater from the cutout in the RV. With the water heater halfway out, disconnect any electrical connections. Remove the old water heater. 

  10. Remove the inlet and outlet 90-degree elbows or straight fittings from the back of the old water heater and save them to install on the new water heater. 

 Installing the water heater

  1. Apply Teflon tape to the ends of the fittings that go in the new tank. Install the 90-degree elbows or straight fittings on the back of the new water heater tank. Make sure the fittings are positioned correctly to reattach the water lines. 

  2. Remove any old sealant from around the water heater opening and clean the surface. Be careful not to damage any graphics or decals! 

  3. This is a good time to remove the old cone washers from the hot and cold water line fittings and replace them with new cone fittings.

  4. Install butyl tape to the backside of the water heater mounting flanges. 

  5. Position the water heater partially into the framed opening. 

  6. Route the inlet gas line through the control housing gasket. It might be necessary to remove the grommet from the control housing. 

  7. Connect the 3/8th-inch LP gas supply line to the 3/8th-inch flare fitting at the gas valve located in the control housing. When making the gas connection, hold the gas fitting on the valve with the wrench while tightening the flare nut. After making the gas connection at the valve, reinstall the grommet.

  8. Bend the control housing flanges 90 degrees and press firmly against the side of the RV. While pushing the unit against the butyl tape, secure the four corner brackets to the RV.

  9. Secure the water heater to the RV’s exterior by inserting the same type of number eight screws in all of the holes provided around the flange of the water heater control housing. 

  10. Use sealant around the opening to seal the control housing for a watertight seal against the RV’s exterior and seal any openings around the grommet at the gas line. 

  11. To secure the door, snap the hinge pin into the clip on one side of the control housing and slide the corresponding side of the door into the hinge pin. Next, slide the hinge pin into the opposite side of the door and snap it into the clip at the same time.

  12. Locate and position the module board as required. The module board must be mounted so it is accessible for service, yet out of the way of children. It should be located in an area where it will not be subjected to moisture, cleaning chemicals, and flammable vapors and liquids. The module board can be mounted using the adhesive backing or with two number six by 5/8th-inch screws or other suitable hardware.

  13. Make the 12-volt DC electrical connections following the applicable model wiring diagrams in the instruction manual. 

  14. Make sure the water connections at the back of the unit are connecting the hot and cold water lines.

  15. Fill the water tank with water. Open both hot and cold water faucets to expel air from the tank. When the tank is full and water flows from the faucets, close both faucets and check all connections for leaks.

  16. Perform a LP drop pressure test, then turn the LP gas supply on and check all fittings and connections for leaks using an approved soap and water solution. 

 

Make sure you correct even the slightest leak immediately.  If the project ever becomes too much for you, or you just don’t want to mess with it in the first place, we here at RV Depot do repairs on RVs and we can get you in today! 


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