Automation pHat relay fluttering with two outputs connected

I’m trying to connect my Automation pHat to my thermostat. I can connect my fan wire to one of the outputs and control it but when I connect my heating wire the relay on the hat starts switching rapidly without any code running.

Any ideas why one of the outputs might be affecting the relay?

What are you actually connecting, can you post details of, or datasheets for the fan and heating devices you’re connecting. Do you know:

  • Their peak/typical current consumption
  • Their voltage

Also, at this point are you running any of the library code?