GC6AA-10E heater manual

Enabling your recreational vehicle with a heater

All the advantages of having hot water during a vacation come with water heaters that can be installed in motor homes, travel trailers, and house boats. Exactly for these purposes, Atwood has designed 6-gallon and 10-gallon heaters, of which the GC6AA 10E is an exemplary model. This particular heater is able to run on either electric or propane, which allows for more flexibility while camping.

Technical specs

Some bits can be deciphered from the model number, that is GC6AA-10E. That ‘G’ on the beginning stands for ‘gas’, whereas ‘C’ tells you that it’s a combination of gas and ac electric. ‘6’ here indicates the capacity in gallons and ‘AA’ marks the type of heating element installed (screwed-in or bolted-on). Finally, those last ‘10’ and ‘E’ show you the number of revision and that your appliance has electronic ignition rather than pilot relight.

Atwood boasts that their six-gallons (22 liters) and ten-gallon (38 liters) productsare distinguished by the lightest weight available in the market. The main components of GC6AA-10E are the heat exchanging unit, DSI system, thermostat, and electrodes.

Heat exchanger

Atwood’s motor homes models feature a heat exchanging unit. The exchanger tubes come as a welded-on part, and cannot be added as a modification later if not factory-equipped. Those buyers interested in this feature should check its availability when getting their new heater tank.

Having hot water when you arrive at the place you are traveling to is exactly what the engine heat exchanger allows your recreational van to do. Besides operating your gas or electronic heater on the move, the heat exchanger is your only option for warming up water. However, driving with a heating unit turned on is considered dangerous and is not a recommended thing to practice.

The GC6AA 10E offers a 110 VAC heat exchanging component that consists of screwed-in/bolted-on heater, a separated ECO and a separated preset thermostat. Both bolted-on and screwed-in heaters come rated at 1400 watts. Made to last, this incolloy element can withstand running in a dry tank for a limited period of time without shorting out.

The heating system is welded to the outside of the water tank with its U-shaped tube of aluminum. Both ends of the tube have SAE hoses connected to them. These hoses will be spliced into the coolant system of your van’s engine, delivering the hot liquid to the aluminum tube when the engine is running. By transferring its heat through the welds, the circulating coolant warms up the water. Due to the specifics of its design, the exchanger will keep the water from overheating and boiling.

Direct spark ignition (DSI)

Direct ignition water heaters by Atwood are currently manufactured being equipped with a thermal cut-off device. This feature looks like a one-shot fuse that by default remains in a closed state and conducts the power to the thermostat. Its heat sensing design allows it, when tripped, to shut down the ignition by cutting current to the main circuit board. The tripping event would be reaching the point of 190 °F (ca. 88 °C), which can occur because of the flue tube or burner getting blocked.

The thermal cut-off is placed on the incoming power wire and directly connected to the thermostat. This device is meant to break circuit permanently and prevent damage from overheating. Primarily, excessive heating takes place when the main burner’s flame starts burning outside the main burner tube. This can happen after periods of seasonal inactivity, when the water heater remains idle and attracts insects that often create obstructions (see the Maintenance section below).

Although a necessary controlling element, the thermal cut-off is simply a safety device within the DSI system consisting mainly of electrodes and a thermostat.


Those provide a spark to ignite propane. The entire electrode system is enabled with a safety lock-out option that triggers in the absence of flame in 6-8 seconds after the spark is created. Sensing no flame heat, the electrodes send a signal to the circuit board to shut the propane valve down. When locked out, the system it can only be switched on manually, using the ON/OFF switch.


The thermostatic device is based on a simple non-adjustable temperature switch. In its default closed state it that conducts power to the circuit board, ready to open should the water temperature reach the level of 140 °F (ca. 60 °C). This level is preset and cannot be controlled, meaning that the water heater will invariably cycle off upon reaching 140 °F. Normally, the water heats up this hot in 20-25 minutes of standard operation. After cooling down to 115 °F or so, the thermostat will turn the heater back on.

Specifics of gas/electric combo functioning

The GC6AA 10E provides its user with the advantages of both gas and electric operation. The propane mode and the 110 VAC heating mode can be run independently or both at the same time, ensuring faster temperature recovery.

After you turn the gas switch on, the device will attempt to light. If something prevents it from ignition for three attempts, the water heater will enter the lockout mode, indicating the change with its red lamp. In the event of thermostat failure, the unit will also be locked out by the ECO and won’t turn on unless reset. Since each mode employs a separate thermostat, a failure of the gas one won’t get in the way of the electric operation, and the tank content still will be heating up. The red illumination will only tell you if both thermostats are in a lock-out state; you can check if either one is faulty on its own by turning the other one off. Another thing to indicate a malfunction on one side would be a slower temperature recovery.


Rather than an anode rod, this heater features a tank with a clad aluminum lining. This kind of a material corrodes much more slowly and does not require replacement on an yearly basis. Other elements of protection include a pressure-temperature relief valve and the ECO which is a limit switch in the gas thermostat.

Off the box, this Atwood model comes with a pre-installed fused circuit board, which will guarantee protection of the electronics from wiring shorts. Your water heater will refuse to operate, remaining perfectly safe if the fuse should open.

The pressure-temperature relief valve in this model complies with the ANSI Z21.22 standard.


The GC6AA 10E supports the general installation along with other approved methods, including Baggage Flush Mount (MPD 93948) and Compartment (MPD 90093) installations.

The simplified installation procedure means that to mount the water heating appliance, for instance, on carpeting, you will only need a metal or wooden panel that extends a minimum of three inches beyond the complete width and depth of the heater. In case of installing the appliance in a place where tank leakage will possibly damage the surrounding area, you will also need a drain pan.  Added below the water heater, the pan can simply be drained to the outside of the coach.


Preventative maintenance

This water heater model is designed in such a way that allows you to do 95% of all the servicing on its front side. The only exception is the 110 VAC heating elements because those can only be accessed from inside the van, on the backside of your heating appliance.

As the burner tube needs to remain open for the inflow of air, it also invites in crawling and flying insects like spiders or mud wasps that can build nests in the tube. Such blockages will result in poor combustion, delayed ignition or burning outside the combustion tube. Disturbances in the ignition can be heard in changed burner sounds or if the usually strong blue flame degrades in appearance to a soft flickering flame or grows distinctly yellow. Obstructions of this kind are very ease to clean and their presence should be checked on a regular basis.

Flushing and winterizing your GC6AA-10E heater

This appliance comes carefully pre-configured for winterizing. Using the plumbing circuit you can pump your antifreeze solutionin the tank drained in advance. For this purpose, the system features a cold water passage and a check valve, with thetee, hose, and thermostatically-regulated mixing valve on board.

Even without the need in winterizing measures, periodic draining and flushing the heater tank will ensure the faultless performance and long life of your water heater. Also, the draining and flushing procedure is necessary before long term storage or storage in the winter conditions. All Atwood modelshave a flush flange meant specifically for that. This ensures that the access door sits flush with the van sidewall.

Removing unpleasant smell

Whether you use your recreational vehicle frequently or for prolonged periods of time, a reliable way to add to the life of your water storage tank is to flush the heater 3-4 times a year. An unpleasant odor may develop if the water you fill the tank with contains high amounts of sulfur.

For the simple procedure of draining the tank, you will need to remove the drain plug. After the tank isthoroughly drained, flush the water heater to get rid of any sediment. Flushing the tank can be done with fresh water or pressurized air. Pressurized air may be applied through either the pressure-temperature relief valve coupling situated on the front panel or through the inlet/outlet valves on the tank’s rear.

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