It is recommended that you drain and flush the hot water heater one or two times a year. Calcium sediments build up, especially is the southwestern states. It should also be drained if you will not be using the RV for an extended period of time or if the motorhome will be stored in during a time of sub-freezing temperatures. Should you let water remain in the tank for a lengthy period, it is likely to develop a VERY foul odor, and a thorough flushing and sanitizing of the tank will be required to eliminate the smell.
To drain the water heater, turn off the water pump or city water. Then remove the plastic drain plug located in the lower left portion of the water heater; it is accessible through the exterior service door. A 5/8" socket on an extension makes the job easy. After removing the drain plug, open the pressure-relief valve to allow air to enter the heater for faster draining.
Many people replace the plastic drain plug with a petcock that can opened for draining, rather than having to remove the plug. With a petcock, you can also put an adaptor on it so you can attach a short piece of hose to prevent the water from running down the side of the motorhome. Of course, to properly flush the heater, you will have to remove the petcock.
FlushingThe easiest way to flush out the water heater is with a special flushing tool available at RV parts stores. It attaches to the end of a water hose and you insert it through the drain opening and spray the inside of the heater. Repeat a couple of times for best cleaning.
Flushing can also be accomplished without the special flushing tool:
a) wait for a warm day, wear sandals
b) heat the water maybe halfway to increase solubility of the stuff
c) pump off, open drain, open air vent, let it flow
d) use a garden hose with a nozzle that fits partway into the drain.
e) with the nozzle tight into the tank, inject some water. If I'm hand-holding the nozzle I'll be able to hold about half as much pressure as the pump would give. That's what I want.
f) watch as the soft crystals spray on your feet.
e) rinse and repeat
Sanitizing
Turn off the water pump and drain the water heater. Add vinegar to an empty water tank, usually 3 or 4 gallon jugs, add some water to that and run the pump until the water heater fills up. Turn it on and let it heat up and then off and let it cool down. If you're in a hurry, not somewhere you can use water from another source, don't heat it up but just let it sit in the tank for an hour or two. Also run the water through the faucets to get some vinegar on them as well. Drain the water heater and use the flush wand until it the water runs clear. Drain and refill the tank and run it through the faucets to clean them as well. Drain the water tank again, refill and you're done. It is recommended that you do this twice a year. It's amazing how much gunk comes out.
Removing that VERY foul odor
Bob Livingston's "The RV Repair and Maintenance Manual" describes this procedure to 'remove foul odors from hot water tanks":
- Shut off the water supply.
- Drain the tank via the plug (anode rod if so equipped.)
- Remove the pressure relief valve (the valve in the top portion of the unit with the lever that releases pressure.
- Replace the drain plug or anode rod.
- Pour in three to four gallons of white vinegar through the relief valve opening (use a funnel).
- Replace the pressure relief valve.
- Open the closest hot water faucet and turn on the pump so the tank fills.
- Turn on the water heater and cycle until the flame shuts down.
- Close the water supply.
CAUTION: THE WATER IS VERY HOT AT THIS POINT.
- Remove the drain plug or anode rod and drain the tank.
- Replace the drain plug and anode rod and refill the tank.
- Repeat if necessary.
- Perform this procedure at least twice a year to maintain a fresh-
smelling tank.
Contributors: John, Jonna, WxToad
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b) heat the water maybe halfway to increase solubility of the stuff
c) pump off, open drain, open air vent, let it flow
d) use a garden hose with a nozzle that fits partway into the drain.
e) with the nozzle tight into the tank, inject some water. If I'm hand-holding the nozzle I'll be able to hold about half as much pressure as the pump would give. That's what I want.
f) watch as the soft crystals spray on your feet.
e) rinse and repeat
Sanitizing
Turn off the water pump and drain the water heater. Add vinegar to an empty water tank, usually 3 or 4 gallon jugs, add some water to that and run the pump until the water heater fills up. Turn it on and let it heat up and then off and let it cool down. If you're in a hurry, not somewhere you can use water from another source, don't heat it up but just let it sit in the tank for an hour or two. Also run the water through the faucets to get some vinegar on them as well. Drain the water heater and use the flush wand until it the water runs clear. Drain and refill the tank and run it through the faucets to clean them as well. Drain the water tank again, refill and you're done. It is recommended that you do this twice a year. It's amazing how much gunk comes out.
Removing that VERY foul odor
Bob Livingston's "The RV Repair and Maintenance Manual" describes this procedure to 'remove foul odors from hot water tanks":
- Shut off the water supply.
- Drain the tank via the plug (anode rod if so equipped.)
- Remove the pressure relief valve (the valve in the top portion of the unit with the lever that releases pressure.
- Replace the drain plug or anode rod.
- Pour in three to four gallons of white vinegar through the relief valve opening (use a funnel).
- Replace the pressure relief valve.
- Open the closest hot water faucet and turn on the pump so the tank fills.
- Turn on the water heater and cycle until the flame shuts down.
- Close the water supply.
CAUTION: THE WATER IS VERY HOT AT THIS POINT.
- Remove the drain plug or anode rod and drain the tank.
- Replace the drain plug and anode rod and refill the tank.
- Repeat if necessary.
- Perform this procedure at least twice a year to maintain a fresh-
smelling tank.
Contributors: John, Jonna, WxToad
Return to FAQ Index