T9 Automatic mode

mluna20

Hi, T9 with three sensors.  Set Automatic mode with heat to 74 and cool to 78.  It s in the 40s outside and and the house heats up to about 80.  Have to turn auto off and switch to cool.  Any idea what is going on?

HVACNUT

Does it still override if it's in Heat mode?
It might not be the thermostat. What type of system do you have? If it's a boiler, could be a bad check valve. 

ratio

What's the thermostat display?

What are the temperatures of the three sensors? Remember that the average of 80°, 80°, and 40° is 67°. Are the sensors programmed in correctly? Is the thermostat sensor used in the average as well?