Originally Posted by BionicTiki
Thanks eye95. I didn't realize my hot water heater had a reset button! It just needed a reset. I must have run it dry at some point. Doh!
Not necessarily, sometimes the ECO/High Limit thermostat trips for unknown reasons. Once reset it may not trip without a reason again. You need to read the manual for the water heater. The gas ECO/High Limit actually controls the 12vdc going to the LP gas valve so if the 12vdc fuse for the water heater blows you will have the same symptom but different remedy.
If you have a LP/Electric WH there will be two ECO/High Limit thermostats, one for gas, the other for the 120vac heating element. Though they will be under the rubber cover, one has nothing to do with the other.