I don't remember when I learned about this but it has become a pretty routine maintenance task in my RV. Once a year, at the end of the season, I descale and clean the RVs water heater. This gets rid of all the built up calcium deposits and scale. It also cleans the electric heating element to keep it working at peak efficiency. This video and procedure is how I perform this simple maintenance item.
Turn off all water and turn off the water heater gas and electric. Using a socket or Water Heater Wrench remove the drain plug or anode rod and drain the water heater.
Wash out the water heater with a RV Water Heater Rinser or turn the city water supply on to flush out any loose debris in the water heater. Reinstall the water heater plug.
Using the RVs or trailers winterizing kit, put in 3 to 5 gallons, depending on water heater capacity, of white vinegar. Fill the rest of the water heater with water. Turn on the water heater electric element to heat the mixture and leave for a minimum of 8 hours. After 8 hours turn water heater off and allow to sit overnight.
After sitting overnight and allowing to cool, drain mixture from water heater. Flush water heater out as you did previously using the water heater rinser or allowing city water to rush into tank. You will see more debris come out and this is normal. Reinstall plug or anode rod and move inside.
Remove the aerators and turn on each faucet, both hot and cold, till water comes out and no vinegar smell can be detected. Reinstall your aerators and your done till next year.
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