I bought two of these at Lowe's while they had there clearance and I'm not sure which one to go with in our house. I got 1 of the 55-SHP10 and 1 of the 55-SHP22 and I'll tell you about our house. It's a brand new construction with 1100 sq ft on the main level and 1240 on the 2nd floor. It's also very "tight" I built it and I chalked and sealed every seam & window before I insulated the walls. I will be putting this unit on the main floor and I'm hoping that the heat will travel up our open staircase and through the floor to the upstairs. My concern with the bigger unit is that it may blow you out of the 1st floor and I don't want that. Also I do have vent-less propane fireplaces in the master bedroom upstairs and in the basement to help supplement if the heat is lacking. I just want to make sure if I go with the smaller unit I'll be able to feel it. Thanks for your help!