Download user manuals for Ariston water heaters in PDF format. Find the reset button location and instructions for each model. reset high limit switchfix ariston electric hot water heatersWORKS ON GL-2.4 t through GL-6 MODELSFix no red light or heat on Ariston hot water heater. You will need to push the reset button to reset the thermostat after the problem has been corrected. Unplug the power cord to the water heater and remove the front cover. Press the reset button firmly with the tip of a ball point pin, extra small screwdriver or similar object. ppP2x.