Atwood EXT water heater LOCKOUT light

Atwood uses same set of t-stats for electric and gas operation since 2004 model year.

The XT uses 'higher factor preset' normal t-stat than the other models.
The normal is set to open at 160*F (vs 140*F other models use) and the ECO (Energy Cut Off/High t-stat) is set for 180*F (which is same as other models).

The higher heating temp is 'mixed' with cold water for a finally output temp of 130*F.....gives the equivalent of 16 gallons from a 10 gallon tank.

IF normal fails to OPEN and ECO OPENS it triggers 'Fault Light' (which also locks out operation). T-stats will reset (Close) when temps drop to 110*F but until fault light is reset no reheating will occur. To reset 'Fault Light' you turn On/Off Switch OFF then back ON.


With ECO operating......normal t-stat has failed OR is not tight against tank wall'

Inexpensive to replace....come as a set.

Atwood part number #91547 for XT Models LINK

Seems a pretty logical approach would be, if the water is not getting too hot, then replace the thermostat.

You replace the tstat. IF the tstat fails to open when temp is met, the temp rises until the ECO trips. At that point your inside light comes on. Doug