Best Smart Thermostat for Steam System

dtmaine

I've got a 1-pipe steam system and would like to replace our thermostat (it is way too slow on sensing changes in the room's temperature). I would like to replace it with a smart thermostat, primarily for the benefits of being able to monitor our heat system while we are away and for the tracking and logging that is provided. My wife also likes the aesthetics of the new thermostats since ours is right in the middle of our living room.

I understand that steam is typically most efficient with limited or no setbacks, which is fine. But I am also curious about some of the 'learning' features I've heard about. For example, with temp overshooting basically inevitable with our current thermostat and system, are there any 'smart' thermostats that would learn how long it typically takes for my system to heat up and, after 'learning' that the temperature keeps climbing even after boiler shutoff, also be able to 'learn' how to preemptively shut itself down before temperature is reached? It seems like that would not be a hard algorithm to program into one of these things.

I know this would be less of an issue if we just kept the thermo at a constant temp, but our house has a ton of south facing windows and so naturally heats up above our set temp during the day, with the heat (in the current season) only firing periodically through the night and early in the morning. We typically leave it set at 65. By 9am the house has naturally risen in temperature to 68 or 70 until it starts to slowly fall again after sunset, with the heat maybe ticking on at 8pm. So even without setbacks, we are periodically firing the system up from dead cold.

Any experience with smart thermostats and what would be the best option for us? I do not have a C-wire.
Thanks!
Dustin

Jamie Hall

Since you have a natural set back sort of built into the system, I would suggest not messing with setbacks -- or smart thermostats -- at all. Steam systems don't mind starting from "dead cold" (really ambient).

What type of thermostat do you have now? Many thermostats either have an anticipator or some other mechanism built in which will reduce the overshoot problem -- if it is properly adjusted. Where most of them have a problem is when the system is truly recovering from a set back; the overshoot will be bigger and may not be really properly compensated.

Some thermostats (including many of the "smart" ones) are aimed at the forced air market, and will not have the anticipator function (since there is minimal overshoot with forced air).

If you really want a smart thermostat, most of them require a "C" wire for power -- since anything connected to WiFi or the 'net guzzles power, and batteries won't cut it. If you really want one, then, you will need to figure out how to handle that.

Further, if you do get a "smart" thermostat, do the whole world a favour and change the password... immediately...