Weird behavior simultaneous Cool/Heat
CT here, mild Spring and last night was the first time we ran AC for cooling. Turned cooling on at 6pm and went to bed at 10pm our home was about 74F, at 1am I woke up sweating and the bedroom was 84F and I felt warm air coming out of the floor registers.
Off to the basement I went and found our propane Combi-boiler tankless running and air handler was cooling and heating. I rebooted the Tankless, shutoff the breaker for the AC and airhandler also rebooted the Ecobee. Turned everything back on and waited, yet the Tankless was still getting a signal to heat. In my frustration found and disconnected the 48v communicating wire between the tankless and air handler. That did stop the heating.
This AM I called the HVAC company that replaced the combo-boiler tankless after Thanksgiving 2025 and they are trying to get out this week. We have cooling and hotwater to shower and wash dishes.
We've been in this house for 5yrs and installed Ecobee tstat within 2-3months after moving in. This is the first time something this weird has happened.
I looked at Beestat and I see the spike in indoor temperature from 11pm to 130am but there is no heating data only cooling.
Any other ideas?