Well, I've been very deligent in keeping the Englander NC-13 rocking and rolling. This is to keep the central heater off, but I think I kinda of found the fine balance line. Its about 15 degrees and its just barely keeping up. Its still 70 degrees in most of the home, but its not been easy. The tipping point seems to be like 20 - 25 is where the fireplace has complete control of the heat. The heater still hasn't kicked on but the heat cycle of the stove isn't what it was. It gets loaded up when it just starts to get between 400 to 500 now, where I would wait till it was like 200 - 300 before to allow the coals to burn down some. What is your tipping point?