How does ECO switch work-Atwood

[TexasTwoStep]

Atwood GE16EXT--Could someone explain the mechanics of how the ECO switch shuts down the voltage going to the lower harness of the module and causes the error light to come on? Thanks

[Old-Biscuit]

Atwood combo models since 2004 use DC & circuit board to control the heating cycles using electric and/or propane.
DC triggers a relay to allow 120V AC to element.
DC opens gas valve and energizes spark electrode.

When on propane 12V DC has to go thru ECO to get to gas valve ECO (Energy Cut Off---HIGH temp t-stat) OPENS at 180*F if normal t-stat fails to control heating cycles (Your Model uses a 160*F T-stat---standard model uses 140*F t-stat)


When on electric a millivolt DC goes thru the ECO to gas valve so that the ECO is part of control loop.....if normal t-stat fails then ECO opens

Any time the ECO opens (electric or propane) it triggers the FAULT Light circuit so there is a 'visually' indication of problem
Fault light also is triggered when propane flame fails to 'prove' it lit.
Milliamp signal is generated by flame via 'rectification'...this signal returns to circuit board proving flame lit. No return signal circuit board drops DC to gas valve so raw fuel doesn't accumulate in combustion chamber. Fault light is triggered due to failure of flame proving signal.
(Basically....when DC is lost on RED wires and still on Brown wires-----Fault Light comes on. If DC is lost on Brown wires 1st........no fault light)

[TexasTwoStep]

Thanks you for your explaination.

[TexasTwoStep]

Originally Posted by TexasTwoStep

Thanks you for your explaination.

So if DC is lost on red wire it can still be on on the brown?

[TexasTwoStep]

Originally Posted by TexasTwoStep

So if DC is lost on red wire it can still be on on the brown?

No, I guess not.

[Old-Biscuit]

Yes DC can still be on BROWN wires when DC is lost on RED


DC from ON/OFF switches (Electric -WHITE/Propane-ORANGE) to circuit bd
DC to thermal/t-stat back to board (BROWN)
DC to ECO/Gas Valve to Ground (RED)


Thermal fuse blows.....DC still on WHITE or ORANGE until switches turned OFF
T-stat OPENS........DC still on WHITE or ORANGE until switches turned OFF
ECO OPENS (or millivolt lost due to resistance etc)----DC still on WHITE or ORANGE and on BROWN until switches turned OFF or T-stat OPENS


(No DC on RED-----no gas valve/propane heating stops or DC on YELLOW for Relay so no AC to element for heating)

[TexasTwoStep]

Originally Posted by Old-Biscuit

Yes DC can still be on BROWN wires when DC is lost on RED


DC from ON/OFF switches (Electric -WHITE/Propane-ORANGE) to circuit bd
DC to thermal/t-stat back to board (BROWN)
DC to ECO/Gas Valve to Ground (RED)


Thermal fuse blows.....DC still on WHITE or ORANGE until switches turned OFF
T-stat OPENS........DC still on WHITE or ORANGE until switches turned OFF
ECO OPENS (or millivolt lost due to resistance etc)----DC still on WHITE or ORANGE and on BROWN until switches turned OFF or T-stat OPENS


(No DC on RED-----no gas valve/propane heating stops or DC on YELLOW for Relay so no AC to element for heating)

Good, thank you.