Last night was the coldest night of the year. 20* & very windy. We woke this morning & I could feel the cold as I came down the hallway from the bedrooms. It felt c-c-cold in the living room, dining room, kitchen. It felt much colder on my feet. As I got to the dining room I'm thinking outfire, blown circulator pump, the underground pipes can't flow enough BTU's.....then.... then.... I noticed the back door wide open. It needs a firm shove to seal & latch it. About twice a year it doesn't get latched. Each time it happens we're real careful for about 6 months.
That being said, the thermostat at nipple height showed 63 degrees. Not bad!