i have several apartments with different heating systems. two of them have thermostats that for example if you set them at 70 degrees they only get to 60 or 65. so you have to set them above what you want the temp to be. one of them is a forced hot air gas heat system with the round honeywell thermostat. the other is a utica boiler steam system with a fairly new Luxe thermostat. i've heard that dust can accumulate on the inner metal pieces of the thermostat and cause it to not work properly. i've cleaned both out. what else could it be? or is it just the heating systems themselves?