Need some help - going on a trip Thursday (well maybe)

Unfortunately the manual also confirmed that temperature is factory set.

Inquiring minds want to know.

On some heaters, I've read, the thermostats can be replaced by one of a different temp setting. I'd assume that the heater MFG's install a thermostat that complies with reasonable temperature and pressure,i.e. not a higher temp thermostat that may cause an issue.

On some, you could choose a lower value to keep away from 140f water, if that's a concern.