Hi there - new to the forum.

Installed the thermostat for a heat pump system w/emerg heat and assumed all wiring was correct (matched to previous thermostat that was functioning normally.) The room temps were off - was reading 10 degrees cooler. Tried to troubleshoot w/Honeywell but was unsuccessful (minimal if any changes were attempted). They are sending a replacement, but I was wondering if there could be a reason for this. There are no drafts coming through the wall and the previous Robertshaw thermostat had an accurate room reading.

Any ideas or could this just be a faulty unit?