I have my Englander 25 hardwired to a digital thermostat and for the most part it works great. If I set it at 71 degrees most of the time it will hold it within a degree or two. Sometimes though I notice that after the call for heat has been met I still get a fairly large flame and then the room temp climbs. In other words why does it not go into an idle mode all of the time once the temp is reached? I understand that the outside ambient temp can cause it to get hotter but I can not understand why there is a large flame when the thermostat is not calling. Any suggestions? Could a weak stat battery cause this?