12 Gallon RV Water Heater

What RVs use a 12 gallon water heater?

12 gallon tanks are standard on many mid-size and larger travel trailers, fifth wheels, and Class A motorhomes where a 6 or 10 gallon unit cannot keep up with back-to-back showers or galley use. Suburban and Atwood (now Dometic) both build 12 gallon models in gas-only, gas/electric (DSI), and gas/electric with motoraid configurations. Confirm your existing model number and cutout dimensions before ordering. If you have a smaller rig, compare specs on our 10 gallon RV water heater collection.

Can I replace a 6 or 10 gallon water heater with a 12 gallon unit?

Usually no, not without modification. A 12 gallon water heater has a larger cutout (roughly 16" x 20") and a deeper tank than 6 or 10 gallon models. Swapping up means cutting the sidewall opening and rerouting plumbing and gas lines. Most owners replacing a failed unit stay with the same gallon capacity for a direct fit. Measure the existing door opening and tank depth before ordering.

What is the difference between gas, electric, and gas/electric 12 gallon models?

Gas-only units run on LP and need no shore power, useful for boondocking. Electric-only and gas/electric (DSI) models add a 120V heating element that runs on shore power or generator, which saves propane at full-hookup sites. Gas/electric models give you both, and the recovery rate roughly doubles when both heat sources run at once. Match the fuel type to your existing wiring and gas line, swapping a gas-only unit for an electric model requires running new 120V circuit.

How do I find the right make and model for my rig?

Open the exterior water heater access door and look for the data plate on the inside of the door or on the tank itself. You need the brand (Suburban, Atwood, Dometic), the model number (for example SW12DE or GC12AA-10E), and the serial number. The Suburban decoder reads SW=Suburban Water Heater, 12=Gallon Tank, D=DSI, E=Electric. Text or call us at 817-984-1852 with that information if you want a fitment check before ordering.

Should I winterize my 12 gallon water heater?

Yes. A 12 gallon tank holds enough water to crack the tank lining or split fittings if it freezes. Drain the tank, remove the anode rod (Suburban) or plastic drain plug (Atwood/Dometic), and bypass the heater before running antifreeze through the plumbing. Our RV winterizing kits include the bypass valves, blowout plugs, and antifreeze pumps needed to do this in under an hour.

How often should the anode rod be replaced?

On Suburban 12 gallon tanks (steel tank with porcelain lining), inspect the magnesium or aluminum anode rod every 6 months and replace it when it is consumed down to about 25% of its original diameter. In areas with soft or treated water the rod can dissolve in a single season. Atwood and Dometic 12 gallon tanks use an aluminum tank and do not require an anode rod, only a plastic drain plug.

Does this collection ship free?

Orders over $100 ship free within the continental US. Full water heater units ship via standard ground freight from the manufacturer warehouse, with typical transit of 5 to 10 business days. Replacement parts (elements, thermostats, gas valves, doors) ship from our warehouse and usually arrive in 2 to 5 business days.