If you look at the Atwood service manual dated September 2003 you will find the following on page 27 :
FLUSHING YOUR WATER HEATER TO REMOVE THE ROTTEN EGG ODOR
1. Turn off your main water supply. Drain you water heater tank. Reinstall drain plug. Remove the
pressure-temperature relief valve. With a funnel use 4 parts white vinegar to two parts water. (In a
6 gallon tank that would be 4 gallons vinegar to 2 gallons water).
2. Cycle the water heater, letting it run under normal operation 4-5 times. At no time do you remove the
vinegar from the tank Once this has been completed, remove the drain plug and drain the
3. After thoroughly draining the tank, to remove the sediment, flush the water heater.
If you elect to use air pressure, it may be applied either through the inlet or outlet on the rear of the
tank or applied through the pressure-temperature relief valve. Remove the pressure-temperature
relief valve and insert your air pressure through the pressure-temperature relief valve coupling. In
either case, with the drain valve open, the air pressure will force the remaining water out of the
If air pressure is unavailable, your unit can be flushed with fresh water. Fresh water should be
pumped into the tank either with the onboard pump or external water pressure. External
pressure may be hosed into the unit either through the inlet or outlet found on the rear of the
tank or the pressure-temperature relief valve coupling located on the front of the unit.
Continue this flushing process for approximately five minutes allowing ample time for the fresh
water to agitate the stagnant water on the bottom of the tank and forcing the deposits
through the drain opening.
4. Upon completion of the steps above, replace the drain plug and the pressure-temperature relief
5. Refill tank with fresh water that contains no sulphur.
The Atwood water heater is designed for use in a Recreation Vehicle. If you use your vehicle frequently
or for long periods of time, flushing the water heater several times a year will prolong the life of the storage
A friend just did his heater and it came out great.
I can send a copy of the manual to all who send their email.
2008 Jayco 322FKS, Hemi, Hensley, Oreo the Malshi, DW and I
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