what size boiler do i need?

[kodo]

i just did a heat loss calc of my house.

it is 75 BTUs/hr (for a 0 degrees day. i live in philly)

what rating BTUs boiler do i need?

thanks,
kodo

[johnsp]

You need a boiler that outputs at least 75K.

[comfortdoc]

i just did a heat loss calc of my house.

it is 75 BTUs/hr (for a 0 degrees day. i live in philly)

what rating BTUs boiler do i need?

thanks,
kodo

0 is much to low. I will guess you can heat your home with 50k. Adjust your program to 14 deg outside temp. It is very rare it stays below this for more than a couple hours on the very coldest days of the year. Set indoor temp at the temp you feel comfortable.

[kodo]

ok, to be conservative i changed it to 10 degrees.

it went down to 65k btu

anybody have any ideas why the installer of my boiler (before my time) put in a 125k btu, and all the proposals i have gotten for a new one (three) have been for about 115k?

the slant/fin heat calc was very thorough.

am i falling into some novice misconception?

as a reality check, my house is
-1700 sq ft
-100 years old
-two-layer brick 1st and 2nd floor (uninsulated)
-frame third floor and attic (heavily insulated)
-double glazed windows
-kept at about 65* avg
-uses the boiler for DHW

thanks,
kodo