Checked first floor Trane air handler with hot water heating coil for no heat checked circulation pump and coil had to purge air out of the loop tested system operations left system working highly recommend to replace the automatic air vent on the return hot water line View visual findings from this job here - https://visionshare.xoi.io/?id=XA-A243-B0A0BFA4A4284F63B37EA4A80D48A6DB