There is a boiler control that, in the application that I saw, wirelessly monitors the temperature in about 30% of the apartments in a high-rise rental building.  So far so good, but it has ‘Green’ in its name, so it is automatically suspect. It uses that the apartment temperatures to switch a boiler on and off.

There is a big flaw in this control strategy. When the controller senses that the room temperatures being monitored are too low, it will switch the boiler on – and keep it on until the temperature in the suites reaches the setpoint. The problem is that there will be a long delay before the hotter water reaches the radiators in the suites being monitored and an even longer delay before the air temperature reaches the setpoint. It could easily take 20 minutes or more. All this time the boiler is firing away. The boiler will be controlled by information that is 20 minutes or longer in the past. The result will be big temperature swings, which is very inefficient. 

Besides, you cannot just switch a boiler on and off as if it were a residential furnace. Rapid cycling will shorten the life of a boiler. Many boilers can be damaged if the return water is allowed to get cold.

Modern controls, both electronic and digital use a control logic called ‘PID’ or ‘proportional, integral and derivative’. Essentially this is an iterative algorithm that records the present trends including the outdoor temperature, compares it with its record of past conditions and determines the level of heat that will be required in the near future. To use a car analogy, if you are merging onto a highway, you know your current speed, and from past experience that you will have to accelerate into a highway lane and you start to accelerate early in anticipation.

Also, in the installation that I saw, the controller was wired in parallel with the operating and high limits of the boiler, essentially bypassing the safeties. They could have blown the boiler up.