I keep getting a DSI fault light coming on when using my waterheater. It will heat up the water just fine on electric, gas or both. I have put the switch on electric only and get the fault, I can put ...
ECO is a normally closed safety temperature switch that sends voltage to solenoid valve. The switch opens if the water temperature exceeds 180°F Here is a link to a manual for an Atwood wh. Atwood Manual
The ECo and thermostat cost about $16.00. Mine as doing the same thing, replaced eco and thermostat solved problem. (both come together on same board)