Recently bought a house in coastal New Hampshire and need to replace the very ancient boiler (hot water baseboard heat.) Got one quote for a Peerless WBV3 boiler with Beckett Burner and Domestic Coil. Got another for Biasi Model B10-4 with Riello burner and Heat-Floss indirect hot water heater HF-40. We don't know much of anything about any of this and are looking for guidance re: the advantages/disadvantages of the domestic coil v indirect and also about the two different boilers. Any help will be much appreciated, the less technical the better!
The indirect will save on fuel during the summer. If it's sized properly, you may be able to use a smaller boiler depending on the system size. Did either or both of your proposals include a measurement of your existing baseboard, or did they just look at the nameplate on the existing boiler?
The total is used to determine the correct size for the boiler. This plus the domestic hot water demand (another calculation the contractor or engineer will need to do) will determine the size of the indirect.
The room-by-room numbers are used together with with the length of baseboard in that area plus a derating chart for your brand of baseboard to determine the system supply temperature needed at design conditions. If the room-by room balance of radiation to heat loss is out of whack, you should be informed and given options. If the boiler can be configured to deliver a variable output temperature based on an outdoor reset scheme, you will get better indoor comfort and burn less oil.