My current boiler is a wall mounted 50K BTU unit generating baseboard (48 linear feet in total) heat for a 1,100 square foot condo. The boiler is one of those units that also heats the water for my shower by running a pipe through a 30 gallon water tank. My heating bills are low and I have no problems with the volume of hot water. I think the current 50K BTU unit is sufficient. My unit has 3 exterior sides, with a neighbor above and a neighbor to one side, and a mostly below grade garage (not heated but never below 40 degrees on the coldest day) below. One estimate on replacement said they could not get a 50K BTU unit as the manufacturer blah blah blah, but could install a 70K BTU unit (Bimini BNC070) . That seems like too much to me. What will my issues be if I were to install the larger unit? I'm guessing my heating bills would actually go up as my limited internet google-fu suggests. So I came to the beeb for the straight skinny. Anyhow, my current boiler has developed a significant leak (drips about 1-2 gallons every 24 hours) and I am getting estimates on repair vs. replacement. My heat and hot water still work so it's not yet an emergency. Long winded I know, sorry, and thanks for the help.
Input and output are two different things, boilers are a little harder to oversize than a forced air system. I wouldn't sweat the extra as its not that much. Now if it was a 90k or something sure. I'm not familiar with that brand. Are you replacing the domestic hot water tank as well?
I will not be replacing the domestic hot water tank, that was replaced just over a year ago. Got my second quote today. First quote was $5,100 to replace the boiler, nothing said about an expansion tank and I'm pretty sure they are not going to replace the two zone valves. Quote 2 (today) was $9,022 includes boiler, expansion tank and 2 zone valves. Crazy thing is that each of the units (quote 1 and quote 2) I can buy myself for about $3,300 +- $200. Seriously, I am willing to pay a fair price but $9,022? Parts in total will be less then $5,000 so they are charging me $4,000 in labor? Plus permits? BTW boiler #1 Bimini Crown BWC070 Boiler #2 Slant/Fin CHS110