I have a 2nd gen Nest thermostat since they first came out in 2012 or so with a hot water system, so I can speak from my experience.
There is a setting on the thermostat (True Radiant) that takes into account the long heat-up times of radiant systems. With this setting off, overshoot is real. On cold days, True Radiant does start the system earlier. For example, it take about 2-3 hours in the deep of winter vs 30-60 minutes now.
However, it seems to be based to on a look-up table rather than an algorithm. It doesn’t take into account forecasted conditions, such as a temperature rise overnight, strong winds or decreasing/increasing radiance of the sun over the season. Those latter factors do make a difference in whether the house reaches the target temperature on time or whether overshoot occurs, and whether I am slightly uncomfortable.
As far as I can tell, there is an automatic set-back for heat pump systems. I wish this was given as an option for manual scheduling in True Radiant mode. To this day, I can’t tell whether there is an effect on efficiency (based on run-times which the thermostat dutifully displays).
I also wish the thermostats (in a dual-zone system with a single boiler) be “genlocked” or run on common firing times with demand prediction for temperatures to make use of boiler run-time, rather than running the boiler just when there is a request for heat in one zone.
There is a setting on the thermostat (True Radiant) that takes into account the long heat-up times of radiant systems. With this setting off, overshoot is real. On cold days, True Radiant does start the system earlier. For example, it take about 2-3 hours in the deep of winter vs 30-60 minutes now.
However, it seems to be based to on a look-up table rather than an algorithm. It doesn’t take into account forecasted conditions, such as a temperature rise overnight, strong winds or decreasing/increasing radiance of the sun over the season. Those latter factors do make a difference in whether the house reaches the target temperature on time or whether overshoot occurs, and whether I am slightly uncomfortable.
As far as I can tell, there is an automatic set-back for heat pump systems. I wish this was given as an option for manual scheduling in True Radiant mode. To this day, I can’t tell whether there is an effect on efficiency (based on run-times which the thermostat dutifully displays).
I also wish the thermostats (in a dual-zone system with a single boiler) be “genlocked” or run on common firing times with demand prediction for temperatures to make use of boiler run-time, rather than running the boiler just when there is a request for heat in one zone.