important safety tip

if you have a battery-powered thermostat, and the thing tells you, just before a weekend away, that the battery is low, change the battery!

the on-off state worked fine, only it kept sending the a/c signal to the pump outside instead of the heat it was supposed to, so the a/c was on 24/7 for the last day at least, and started to freeze the pipes.

no damage done, but damned cold and annoying...