I don't have a heat loss for my house but I do know how many BTU's Im using by doing the math 1 gallon oil = 136,000 BTU's. So in November and December I used 223 gallons or 497,180 BTU's a day. And now in colder January I used 170 gallons or 745,806 BTU's a day. Heres my question why are all the boiler companies telling me I need the bigger Model. If I look at the Empyre Elite 100 with a 66,000 BTU per hour burn if I run it twice for 8 hours that would be 1,056,000 BTU's plenty more than I need. The 200 would be 1,760,000 BTU's for two 8 hour burns. Is my thinking correct here or am I looking at this the wrong way?