Boiler sizing

Peteys

I have a 5 family house (3 stories) that has about 520 sq ft of edr attached. Apartments are around 700 sq feet. 19 radiators total. One pipe parallel flow gravity that drips into a dry return (30 feet) one side and (15 feet)the other side, and then into the wet returns. Main vents are up on a nipple at the end of the dry returns where they drop to the wet. There are no vents on the mains or risers, only on the end of the dry returns? There's 2 mains, one 50 feet of 2 inch, the other 10 feet of 2 in. Dry returns are 1 1/2. I'd like to have a wm 80 gallon super store iwh. I also have about 25 feet of hot water baseboard heat in a room in the basement that runs off the boiler.



Would use size the boiler based on edr or go higher?



Many thanks

Jamie Hall

Sizing

is based on the EDR.  Unless you are going to use an awful lot of hot water, there will be ample capacity.



Provided, that is, that all your mains are insulated, as they should be.

Peteys

Edr of baseboard

Thank you. And would you know what would the additional edr that I would have to add for approximately 25 to 30 feet of baseboard if I were to get a new boiler?