RE: Water Heater
At the unit itself, there is a toggle switch, marked on/off. In the potty room there is a switch marked water heater (in addition to the gas one) also marked on/off. Do I have to turn both of these on? I did, and I’m getting hot water, but still not sure why the two switches.
The switch on the back of the water heater is a master off, for the electric heater. If it is turned off, the electric will not operate, but the gas side will. The gas part does also require a 12V-dc power supply, while the 120V-ac does not. The master must be on for the inside switch to work as it is there for the service tech. as well as the fact that not all RV builders add the inside switch. The switch for the gas side should also have a light with it which should turn on when you first flip the switch, then go off after the fire ignites. It would stay on if the fire does not light. The two switches inside do not both need to be on, but they can be. If they are, the electric will start first and unless you are using a large amount of hot water, the gas will never light. This allows you to use the propane as a back-up and to help to keep the water hot when taking a shower or other large uses of hot water. The propane should heat the water much more rapidly than does the electric. It is also designed for the electric to start several degrees before the gas does, to conserve gas if both are in operation.
If you wanttest the propane, the easiest way is to turn both off for an extended period to allow the water to cool. That will take several hours. After at least four hours of "off time" turn on only the propane switch and check to see if it lights. You should be able to hear it when outside and near the water heater if it is on. You can also open the access door and look as the flame is visable in the lower right corner of the water heater. If it does not heat the water, there is some problem and it should be repaired.
"Also, is there any way of turning down the heat? The water is extremely hot "
The answer to this is no, unless you get an adjustable thermostat and add it to the unit. There used to be some available, but I have not seen one in some time so I'm not sure that they are still available. The reason that RV water heaters are set so high(usually 140 degrees) is so that the water can be mixed with cold to make it last longer when taking a shower and such.