How to Flush a Suburban RV Water Heater

We’ve been in the motorhome for just over 15 months and figured it was time to service the water heater. Who knows how long it has been since the previous owners did it either. Wondering how to flush an RV water heater? Here are the parts needed and exact steps to perform the water heater flush for a Suburban 12 gallon in a 2014 Tiffin Phaeton. Don’t have time to read this now? We only recommend products we love and your support means a lot to us! This post contains affiliate links and if you make a purchase after clicking on our links we will receive compensation at no additional cost to you.

Parts Needed

• 1 1/16" socket to remove the factory anode drain plug
• 3/4 NPT Male plastic drain plug to use when filling the tank overnight with a vinegar and water solution
• 1 1/8" socket to put on and remove the drain plug above
• Water heater tank rinser
• Replacement magnesium Suburban RV Water Heater Anode Rod. Suburban sells an aluminum one for twice the price, but you don’t need it unless your magnesium one is eaten away in a year.
• 6 gallons of vinegar. Costco sells 2-gallon packs for $4.69, but if you don’t have a membership they are around $2.70/ga at Walmart or check Dollar Tree.
  • Our water heater is 12 gallons, but we are going with a 50% vinegar and 50% water mixture on the safe side. If you think the corrosion is really bad, you can go 100% white vinegar.

Instructions

Drain RV Water Heater

1. Make sure the water heater bypass is in “normal” mode. It probably already is.
2. Turn off city water and the water pump so the water heater stays empty when you drain it.
3. Turn off the gas and electric heating elements in the water heater so they do not burn out once the water is drained.
4. Remove the outside access cover to the water heater.
5. Open the pressure relief valve, which will speed up how fast the water drains out.
6. Use the 1 1/16" socket to remove the drain plug and anode. They are the same one-piece part. You can throw the old anode rod and drain plug away since you’ll be using a new one later.
7. Let the water drain out.

Flush RV Water Heater

1. Flush the tank with the water heater tank rinser on a garden hose for a few minutes until the water runs clear. You’ll probably have a small mess of limestone debris on the ground along with a huge puddle of water.
2. Use the 1 1/8" socket to put on the plastic drain plug. You can probably just hand-tighten it since it’s only staying on temporarily.
3. Remove the inlet hose from the water pump and attach the vinyl hose, the same one that came with your Tiffin for winterizing, to the water pump inlet.
4. Put the vinyl hose in a bottle of vinegar.
5. Turn on the water pump, which should start sucking in the vinegar. It’ll go into the water heater since it’s the only void in the water system.
6. Repeat for all six gallons of vinegar. The water heater is about 50% full at this point.
7. Turn off the pump.
8. Remove the winterizing hose and reconnect the water inlet pipe to the water pump.
9. Turn on city water. The water pressure relief should still be open on the water heater.
10. Water will fill the remaining space in the water heater, about 6 gallons more. When the tank is full, water will come out of the pressure relief valve. Now is the time to close it.
11. Rinse off any vinegar that may have gotten on the paint on the side of the motorhome.
12. Enable the water heater bypass valve again to keep vinegar water from getting into the rest of the system. Note: both cold and hot water taps will produce cold water for now, so take showers or do dishes beforehand.
13. Turn on the heater element overnight, which will speed up cleaning action.
14. This is also a good time to remove the faucet aerators on the sinks and soak them in vinegar overnight too, to clean off hard water deposits.
15. The next morning, turn off city water, heating elements, and the water pump.
16. Open the pressure relief valve.
17. Remove the plastic drain plug. Use protective gloves since the vinegar water is hot and some may splash on you.
18. After the vinegar and water solution drains, use the rinse wand to give it a good rinse.
19. Put in the new anode rod with pipe tape.
20. Disable the water heater bypass and go back to normal mode.
21. Turn on city water.
22. Once the tank is full and water is coming out of the pressure relief valve, close the valve.
23. Turn on all faucets, after reinstalling the aerators, and the shower until the air is out of the system.
24. You’re done.

Conclusion

If it is time to flush your RV water heater order these parts from Amazon and follow these exact steps to service your Suburban 12 gallon in your 2014 Tiffin Phaeton.

Want more RV repair and maintenance information? Wondering how to keep RV pipes and holding tanks from freezing? Take a look at our Motorhome articles.

Get the parts from Amazon: