At what temp does 'Overheating' trigger?

Hi all, title says it all. I'm using a Plus1PM to control a ~2500W water heater, and it's been fine for the last 5-6 weeks. However the Plus1PM switched off the boiler twice today (the relay to the heater switched off; the Plus1PM kept running OK).

I'm curious how hot the Plus1PM needs to be before switching off the relay due an Overheating incident?

Many thanks!

Dan

OK great thanks!

I have a feeling that I may have slowly killed this Shelly, it should have been OK according to specs (the heater draws max 2600W @ 240V), which is below the 16A limit.

In the end I used a Shelly to remote control a 25A DIN contactor in the main circuit box for the water heater. I lose the power metering capability, but the Shelly can't overheat.