I am adding a pellet stove to our house and trying to decide between a pelpro pp130 and castle serenity. The house is 1800 sq ft but we are looking to supplemental heat our main floor, second floor is only two bedrooms and a bathroom. The pelpro has a higher BTU and recommended heating area than the castle but how are the higher btu's obtained? Is it just a bigger pot and able to burn more pellets and blow hotter air? Also how accurate are the recommended heating area's from the manufacturers? We will be heating fairly open roughly 1300 sq ft but wouldn't the heat get upstairs decently well too? Also for the sizing we live un central VA and have fairly mild winters, usually in 40's and 50's. We would mainly use it when its cooler in evenings around 30's and sometimes in 20's. Any input us greatly appreciated