Atwood DSI fault

Thank you so much for your suggestions, will try that and let you know what happens.

OK...........

2 things come to mind

1st.....least expensive
The control system for propane and electric use the same set of t-stats (ECO/Hi Temp & T-stat/normal temp)

When using the propane \
FULL 12V DC Voltage comes from control module to ECO to Gas Valve via RED wire then to ground from Gas Valve via BLACK wires (Full 12V DC needed to OPEN/Hold Open Gas Valve).

BUT when using electric \
Very low DC voltage is sent from control module to ECO to Gas to ground so that the ECO is part of the control circuit for backup to normal t-stat (safety)
IF this low DC Voltage is interrupted on the ECO circuit (ECO Opening OR loss of voltage) the electric heating stops and Fault Light comes ON.

DC Voltage can be interrupted easily....corrosion/dirty contacts/loose contacts etc.
The lower the DC Voltage the easier to interrupt.

Check the terminals/spade connectors on ECO and Gas Valve (RED wires) and the Gas Valve to ground connections (Black Wires).
Need to be CLEAN & Tight.
Might be just enough resistance to stop the low DC Voltage when on Electric BUT not enough when FULL DC Voltage is used with propane.


Other thing \
Control Module Valve Track circuit bad. Replace module

Sorry for the delay, the fault light does not come on when using propane..

Hey OP..........

Why bother posting seeking help then no longer respond :H :S

Fault light comes on when:
Propane fails to light off (3 attempts) and 'Locks Out'
ECO (High Temp T-stat) OPENS (180*F)


Regardless of heating source....if ECO OPENS it shutdown ALL heating and triggers Fault Light

ECO will reset when temp of water drops below 110*F
Fault Light can THEN be reset by turning switch OFF then back ON

ECO only OPENS when T-stat (Normal Temp) has failed to Open (140*F)

Does Propane come on...or throws fault light