I have just bought a boat with this Can you tell me the startup procedure for the heater as the previous owner never used

Hello Kenneth, thank you for getting in touch. Please can you advise your Eberspacher heater model? This thermostat controller ( in most installations) will switch on the heater via the on/off switch, then the heater will regulate according to where the temp rotary dial is set to. But for best advice we'd need to know your heater model