We acquired a used, but barely used Sierra 4700TE this summer for a song to install in our very vacant, cold and huge ‘71 fireplace. In the two years prior, our South Carolina monthly winter bills exceeded $300 to “heat” (if you want to call 65 degrees from a heat pump, warm.) our 1971, 2200 sq ft two-story. Well, drum roll, we got our first utility bill after the first snow and it was a whopping $129. ❤️ I grew up with woodstove heat and my husband and I will now do nothing different.