replacing my boiler, what brand and is size correct.

i'm gonna replace my boiler. i did a heat loss calc on slant fins app and need 100,000 btu's. i'm gonna use a 45 gal superstor indirect system and do one zone for 1st floor and another for 2nd floor. does any of this change the size boiler i should be looking for?
right now i'm looking at a weil mclain gv90, burnham apline and a peerless purefire. any opinions on which is better or is there another brand i should be looking at?

 

First off I need to ask the size of your home. I am assuming about 4000 sq ft above grade for that kinda heat loss. I do find many heat losses done without reading all the instructions and researching some information like OD design temperature it usually is incorrect.
The amount of heat zones does not change the heat loss nor does the amount of radiation. I normally will not change the size of the boiler due to an indirect water heater (IWH) providing there is not a huge hot water demand.
All boilers are good it is the installation that makes and breaks the quality of the boiler.
I like high efficiency boilers and the Alpine has been around since 2008 and the control strategy they have with the Sage 2.2 control has many troubleshooting screens and programing options. Their new Sage Zone Control will add another 10% to 20% fuel savings as it communicates to the boiler and limits the firing rate of the boiler by heat zones or DHW demand.

 

my basement is heated so including the basement house is 3650 sq ft. its a brick tudor. 3 stories with no insulation and single pane windows. house is about 110 years old. i live in the ny metro area so i used a 15 degree outside temp and 68 degree inside.
i'm thinking i may have a change in plans. over the next 5 years i plan on redoing half the rooms in the house and insulating everything along the way (what i dont tear apart i'm gonna have blown in done). i'm also gonna replace all the windows. i need a new boiler now so i'm thinking i might put in a standard efficiency for now and then switch to a high efficiency when i'm done so that when all the work is done i can fully take advantage of energy savings. for fun i changed all the window values to double pane and proper insulation through the whole house and the btu usage went down to 54,000. so it seems like if i do a high efficiency now i'd wind up with a way oversized boiler in 5 years. we plan on staying here for at least 25 years so the payback period is there. i have to wait on the windows due to some foundation issues that we've started to correct but its gonna take some time.

 

Sounds like an ideal place for a boiler with modulating firing rate burner. Your can also just cut the firing rate of a new boiler and increase the efficiency as you do. Look on it as "manual modulation" instead of built in modulation.

 

What is wrong with the current boiler? Maybe get a used boiler for now.