how big a boiler do i need for a 1000 square foot house in western montana?

Question

I need a used boiler and wonder if i get one bigger than needed how it will affect the efficiency.

Answer 1

I cannot give you a specific size, nor will i feed you a lot of fodder. But you will not need a large one. A larger one may boil more water, which could be wasted since your temperature will reach its desire in the same amount of time. I would not go over what you need.

Answer 2

You can use the International Energy Code. You need the ratings
of the resistance value of your insulation in the attic ,walls and basement which is considered an envelope. You also need the r-
value of all glazing( windows,skylights etc.) The r-value of your doors. These will give you your heat loss and grain. The IEC
has a table for the number of heating days for your area.
These number are put into a program which will tell you the required number of BTU input @ output for your house. When you buy the boiler the heating contractor must do this for you because it is required for the heating permit. You must check with your local Bld.Dept. for any new amendments to the IEC.