Close Call Today - Thermostat malfunction

[thecoalman]

Originally Posted by North Beach Person

The service tech came out and replaced a zone valve.

That will do it, the valve opens and closes on demand for heat from thermostat. Woke to bedroom once that was 85. The other zone was calling for heat and since the valve was stuck open it kept on pumping heat into the room. In addition to that you can get a thermosiphon loop action working and the heat can naturally work it's the loop even without the pump running.

[Nonesuch]

This sort of failure mode is why I am reluctant to deploy home-automation controlled thermostats, much less internet-managed models like Google's Nest.

IIRC, one of the common home-automation managed thermostats (Insteon?) would commonly fail "closed", would just lock on "heat" and not shut off. Not a good failure mode!

Originally Posted by Wmsn4Life

Why would you set it to 49? Setting it that low makes the system work way too hard to warm up again. How old is the system?

Not sure that there is such a thing as "makes the system work way too hard to warm up again". If anything, running longer puts less stress on the system than short cycling.

I do see two drawbacks to a very low nighttime setback. First, it will take a long time to warm up again, so you need a smart thermostat, or you need to set the clock so it starts warming back up an hour before you actually get up.

Second, I set my thermostat to 55F at night, because I've been told that going lower than 55F has an increased risk of frozen pipes (for example, under a sink on an outside wall where it could get much colder than the thermostat setting).