Adrian was prompt. He appeared at the time he said he
would be there. He had the new thermostat ready to install and proceeded with the de-install of the old Honeywell Thermostat and then the re-install of the new Nest thermostat. The wiring was a bit tricky, so we had to do some additional tests to make sure that it was working properly. I helped him out a bit by researching the error code that the Nest gave us. That gave him the final clue as to why we were only getting hot air. The E78 error code indicated that the O/B wire was not connected. As it turned out that wire was required for the heat pump to operate properly. It is all good now.