I'm just getting started with home automation and successfully wired up my pool pump and downstairs HVAC. For the upstairs HVAC I followed basically the exactly same process as I did with my downstairs one (buck converter as supply, 8266 using tasmotize, 3 relays and a temp sensor). The supply is dialed in to 5V but when I plug it in I can't connect to the esp8266 via wifi (offline) and 2 out of my 3 relays switch on even though the state is stored to off. One of the devices makes some noise, can't really tell which one it is as the issue disappears once I change anything (which renders my setup useless, so that's not a solution ).
If I disconnect the relay input's of the 2 relays the esp8266 comes online, if I then connect the relay's everything works just fine.
Would really appreciate any tips anyone might have, not really sure what I can do to fix this.