I'm planning to be away for a week in February and was thinking about getting some sort of temperature monitor that worked over wifi. I'd like to be able to check in on the house temperature and possibly get an alert sent to my smart phone if the temperature falls below a set point to indicate a heating failure. I see a few options out there and some mixed reviews on wifi connectivity issues. Has anyone had any personal experience with these devices? Wifi thermostat seems to be out as this is an older house without the power/common wire.