On this page:

•  General Information
•  Atwood Products Service Info
•  Electric Breaker Switch
•  Troubleshooting
•  Tank Cladding Info
•  Flushing
•  Tank Corrosion
•  Winterizing

General Information

The Rialta uses an ATWOOD Water Heater that is a 110V AC ELECTRIC water heater that also uses the hot engine coolant to heat the domestic fresh water. Winnebago sometimes calls this feature "motor aid". The heater runs ONLY on 110V AC and is controlled ONLY by the "toggle switch" that looks like a regular household light switch that is located on your left side just as you enter (Model 22FD) or on the lower wall under the wardrobe closet (Models 22QD and 22HD). There are no 12V parts or propane parts connected to the Hot Water Heater. There is no adjustable thermostat that can be set by the user.

The manufacturer is ATWOOD Products in Rockford, Illinois and is described as a 4-gallon Marine Water Heater, Model EHM 4-SM.

The heater holds only 4 gallons and the temperature is pre-set at the factory and can not be changed by the owner. All 110V marine water heaters have a recovery rate of 8.2 gallons per hour which means it would take this 4 gal model about 30 minutes to fully heat the water.

Atwood Products Brochure Marine Type Water Heaters (PDF)

 

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Service Info from Atwood Products:

Links to all files in Adobe PDF format.

Pressure-Temperature Relief Valve (PDF)

The relief valve is an Atwood 91604.  The Camco 10421 or 10423 should also work.

Water Heater Care and Maintenance Brochure from Atwood (PDF)

Aftermarket Heating Elements (PDF)

 

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Electric Breaker Switch

Concealed deep within the electrical connections box is a pesky electric breaker switch (overtemp). It does not look like a regular full size circuit breaker but rather is a small red (or brown) rod about 1/8" in diameter which will project out of the top electrical connections block. Simple use your finger or small object to push in to reset the switch.

The biggest problem is getting access to this small switch. The white cover over the electrical connections needs to be removed. In reality, you need only remove one of the two screws on the side of this cover plate. Then the cover can be swung away (and slight bent out of the way) to exposed the electrical connections.

When done resetting the breaker switch make sure to replace the cover and any screws that you removed.

Note: You can replace the over-temp sensor with the automatic reset ECO from Atwood kit 91447.  You can also use kit 90037 to replace the large sensors on the older units, including a new holding plate, but it will have the manual reset.   You can buy an automatic reset over-temp sensor separately as p/n 6UEA0 from many electronic supply stores.

 

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Troubleshooting

If the hot water heater fails to operate electrically, follow these steps:

1. First, check to be sure that the 110v power is connected. If connected to shore power, make sure your cords are firmly plugged in. If running on Generator power, make sure the shore power cord is plugged into the generator outlet. On the Rialta, one easy way of knowing if the power is on is to look at the microwave and see if the LED display is energized.
    

2. Next, check to make sure the ON-OFF switch for the heater is in the ON position (normally it will be angled upward just like a regular light switch).
    

3. Next, check the breaker in the Rialta Load Center panel.
    

4. If the heater still fails to work, there is a breaker/overtemp located behind the water heater electrical service panel on the side of the water heater itself. It is a very small red or brown tab that will poke out from the thermo overload switch when it opens. I have heard of some reports of this breaker on the heater being tripped when the generator starts up and possibly  sends a brief electrical spike to the heater. I suggest that you keep the heater switch in the off position while starting the generator because getting to this little breaker inside the heater service panel is very difficult. If it keeps breaking, you should contact Winnebago or your RV dealer for any info they may have on the problem.

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Tank Cladding Info

The Atwood water heater tank is constructed of a core of high strength aluminum. The interior of the tank consists of a 15% thickness of type 7072 aluminum (pure aluminum and zinc) that is fused to the core during the rolling process.

This material protects the tank from the affects of heavy metals and salts found in waters throughout the country. It is anodic to these heavy metals and acts much like an anode in a steel glass lined tank except it will last much longer.

There is also no need to replace an anode on a yearly basis.

Flushing the tank on a regular basis has been found to be helpful in insuring the best performance of your water hater and adding to the useful life of the tank. For flushing instructions see your owners manual or contact Atwood for a copy of our recommended procedures.

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Flushing

FLUSHING YOUR WATER HEATER TO REMOVE THE ROTTEN EGG ODOR

Hydrogen sulfide can result when the protective cladding on the interior of the tank is doing its’ job by preventing corrosion and therefore premature tank failure. The electro galvanic action of the cladding material releases hydrogen from the water. If sulfur or any of its’ combinations are present in the water the two will combine and produce hydrogen sulfide. This compound produces the “rotten egg odor”. Hydrogen sulfide can also be present in your fresh water supply. It is the product of the decay of animal matter and as little as one mg/liter can cause a perceptible odor. Smell the water before starting the flushing procedure. If your fresh water has the rotten egg odor, you will need to find another source of fresh water before flushing and refilling the entire water storage system.

1. Turn off your main water supply - your pump or your water hook up source.
    

2. Drain your water heater tank. Due to the location of the drain plug, approximately two quarts of water will remain in the bottom of the tank. If while draining the unit you note that it is flowing sporadically or trickling, instead of flowing steadily, we recommend one of two things. First open your pressure-temperature relief valve to allow air into the tank and secondly, take a small gauge wire or coat hanger device and prod through the drain opening to eliminate any obstructions.
    

3. After thoroughly draining the tank, to remove the smell, flush the entire system from water inlet all the way to holding tank.

For flushing,  use four parts vinegar mixed to two parts water 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 part. 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 unit.

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 valve. 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 tank.

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Tank Corrosion

Pinhole leaks from galvanic corrosion may cause the water heater tank to fail. Microscopic particles of metals (like iron and copper) suspended in water, set up a reaction inside the water heater that is not unlike the principle on which an automotive battery operates. The aluminum tank is the anode and the metals in the water serve as the cathode. Consequently, the aluminum gradually sacrifices itself and aluminum particles are carried away with the water flow.

A white scaly material (aluminum oxide) often is formed around the points where the heaviest action is taking place and heat accelerates the process. Severity of the problem varies considerably in different locales depending on the metal and mineral content of the water. White deposits inside the water heater tank are usually from water impurities that have settled out.

Periodic flushing of the water heater tank under pressure is recommended to slow down this process. For flushing instructions see your owners manual or contact Atwood for a copy of our recommended procedure.

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Winterizing

1. Turn off your main water supply, that is, your pump or your water hook up source.
    

2. Drain your water heater inner tank. Upon doing so, you will note that, due to the location of the drain plug, approximately two quarts of water will remain in the bottom of the tank. This water contains most of the harmful corrosive particles. If while draining the unit, you note that it is flowing sporadically or trickling, instead of flowing steadily, we recommend one of two things. You should first open your relief valve to allow air into the tank and secondly, take a small gauge wire or coat hanger device and prod through the drain opening to eliminate any obstructions.
    

3. After thoroughly draining the tank, you should then flush it with air pressure or fresh water. If you elect to use air pressure, it may be applied either through the inlet or outlet on the rear of the tank. It may also be applied through the relief valve part. In this case, it will be necessary to first remove the relief valve support flange. In either case, with the drain valve open, the air pressure will force the remaining water, along with the corrosive particles, out of the unit. However, if air pressure is unavailable, your unit can be flushed with fresh water. Fresh water should be pumped into the tank either with the assistance of the on-board pump or with the assistance of external water either through the inlet or outlet found on the rear or the 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 thus forcing the deposits through the drain opening.
    

4. Upon completion of the steps above, replace the drain plug and the pressure-temperature relief valve.
    

5. After this procedure, there will be approximately two quarts of water left at the bottom of the inner tank. Should this water freeze it will not cause any splitting of the tank.

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