Home heating automation

deezell

https://www.boards.ie/discussion/comment/122937444#Comment_122937444

On off is how a dumb mechanical thermostat works, it stops firing when the measured temperature passes threshold, it start firing when temperature drops below. With a mechanical stat there is considerable lag or hysteresis, as it can take several degrees either side of target to turn the stat on and off. Add this to the overshoot caused by the fully heated rad continuing to heat after the boiler turns off, and the continued cooling on firing as the flow must heat up before the rads can have an effect, you can have a room temperature which goes up and down by several degrees. Even electronic stats which can trigger on or off on a fraction of a degree difference will have this latter issue.

Smart thermostats use a number of techniques to achieve and hold a steady temperature. PID control is one, predictive learning is another, and to facilitate this is variable rate of heat delivery. As the boiler can only deliver heat at a constant rate, a method known as modulation is employed. This is your 1 2 3 tics, whereby the boiler will cut and restart even though target is not reached, but is approaching, in oder to land smoothly on the target temperature. Once there, the same technique is used to mini boost the boiler though temperature may be above target but falling, so that the temperature does not have a significant lag.

Most cheap electronic stats and many general pupose automation sensors will lack these features, or may require programming to achieve more accurate control. Smart stats will also use learning to determine the rate of heating or cooling dynamically, and also in conjunction with local weather temperature readings. It all makes for a more comfortable experience, and removes the incentive to be a human thermostat, constantly leaping up to nudge the stat up a few degrees, pulling it right down as the room becomes uncomfortably warm, and repeat until bedtime.

TheSunIsShining

https://www.boards.ie/discussion/comment/122937858#Comment_122937858

So is it clear whether 1 tick in Tado has the boiler on or off?

deezell

https://www.boards.ie/discussion/comment/122937868#Comment_122937868

Both. A little on, a little off.