It's the dead of winter. Outside the temperature is below freezing. Your building is sending up heat, and you've got
your windows open. What's going on? Why can't your building's heating system just make everyone comfortably warm instead of turning your apartment into an oven?
What's going on is that most boilers are controlled by the outside temperature. A simple reset timer mounted on the outside of your building reads the air temperature and, based on that reading, instructs the boiler to cycle on for a predetermined period of time. The heat starts coming up, and it gets warmer and warmer inside the building; but, of course, the temperature stays about the same outside. And because it's generally true that the lower the temperature outside, the longer the boiler runs, inside it gets warmer and warmer still, wasting fuel and making residents uncomfortably hot. And that's when the windows start to open.
The obvious solution is to somehow control the boiler's cycles based on the temperature inside the building. That's what indoor computerized heat sensors are all about. A number of unobtrusive heat sensing devices about the size of light switches are mounted on walls throughout the building, usually in residential units. These sensors feed temperature information to a main computer most often connected by wires to the boiler/burner system (although there are wireless systems). The main computer processes the information and, based on its readings, cycles on and off until the average temperature of the sensors reaches a preset comfort level. When that happens, the computer instructs the boiler to cycle off. The cycle repeats itself constantly, maintaining comfortable temperatures throughout the building.
Temperature Controls and More