Total sq ft about 3150. 2000 in the original Victorian on two floors and rest in a single story addition that contains our kitchen, one other room, and the apt. This addition has lots of insulation in the ceiling--2' in places which I put in when I replaced the ceilings.
So, we heat the 1000 sq ft downstairs of the original Victorian and the addition. System zoned 3 ways, up and down in original house + addition. Some heat obviously migrates upstairs but apart from our south facing bedroom, it stays at 50 degrees or lower.

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1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13