Hey guys, we are getting all of our ducks in a row for a new forced hot water baseboard system (upgrading from steam). As an engineer and overall geek I like to educate myself on projects that will cost alot of money, especially when I have to hire someone else to do it. I downloaded Slant/Fin's "Hydronic Explorer" Heat Loss Program to make my life a bit easier. I was shocked at the results! We have a 110 year old two-story colonial that measured in at 1525 sq. ft. It is fairly well insulated. About 20-30 years ago (a guess), the previous owners had blown-in insulation installed in the walls and attic. Assuming it hasn't settled too much the walls should be R13 and the attic should be R19. I have installed new double-pane low-e windows throughout and insulated steel entry doors as well. The house is fairly tight and does not have many drafts at all. That said, I meticulously entered all the data room-by-room for both floors into Slant/fin's program using a 70 degree desired indoor temp, 0 degree outdoor temp. I was shocked that I only had a heat loss of [B]41,500 btu's![/B]. For those of you who are familiar with heat loss calculations....does that sound about right for a 1525sqft, two story house that is fairly well insulated? The reason I was shocked is because the boiler for our existing steam system has an output of 90k btu. Of course, the current steam system only provides heat on the first floor. :wall: I did have a question on the heat load calc that wasn't too clear to me: When calculating the window/door square footage, do you have to include the interior doors? i.e. the entrance door for a bedroom? Thanks for the advice guys!

We have a Amtrol WH7L water heater and if it had an internal leak (Coil leaking) would that cause pressure to build in the boiler?