It would seem as though it is but remember the 100,000 is the input. you will multiply it by the efficiency (80 or 90 or 95%) to determine the output. Unless the house is older with poor insulation and you live in the northern parts, it will probably be oversized. Your furnace is a 90+ so your output is close to 90-95,000 btuhs. To give you some idea, I can heat my 2300 square foot home with a 75,000 btuh input but I live in the mid-atlantic. You want to be careful oversizing a condensing furnace. I would certainly recommend a load calculation be performed.