Can I use my old IHD and the new one at the same time? Follow Yes, both IHDs can be used at the same time and will it NOT affect the functionality of either IHD. Related articles How does the Trio connect to the smart meter? Why do I need a new Trio IHD, in addition to the IHD I already have from my energy supplier Why is my Trio In Home Display not showing any readings? How do I set up my Trio In Home Display? Why is the System Status screen on my Trio IHD showing a WiFi error? Comments 0 comments Please sign in to leave a comment.