We have gas heat and 4 heating zones in our house. We have baseboard heat in all but 2 rooms where there are traditional radiators built into the walls. The basement zone always seems OK, but the other 3 have from time to time kept the temp rising past what the thermostat is set at until we have shut it off completely. Once we do this, it stops coming up and goes back to normal the next time it is turned on. Until now. Now the upstairs zone and the zone for the first floor addition have become completely possessed. It's 83 degrees in the addition and the thermostat has been all the way down for over 24 hours. The upstairs one turned off for a while, but is again coming up very slowly. It's 71 degrees up there. Does this sound like a thermostat issue or some larger problem?

Help!! We have a baby and it's getting hot in here!!

You have a control problem. Unless you know controls I suggest you call a pro to fix this.