I have been trying to replace an 80-year old oil-fired snowman boiler with a new heating system. The oil heating dealers I have spoken to don't seem to have any idea of how to correctly size a heating system for our house.

Now that I've done the figures myself, I find they are all trying
to sell oversized systems. They base system size on the amount
of surface area of the radiators in the house, which was determined by the builder over 80 years ago, when houses were less insulated, more drafty and oil was cheaper.

The area we are looking to heat is about 1800 s/f - the 2nd and 3rd floor of a 2-family home.

The contractors suggested boilers in the 130,000 BTUH range. When I calculated using the actual surface area of all the radiators in the house, I came up with 85,000 BTUH..

According to our state's energy savings program, the proper way to do this is to calculate total heat loss from the house, and this points to an even smaller boiler.

I still would like an oil-fired system. How do I find an oil heat contractor in the Boston area who will do this correctly, and not just rely on a rule of thumb?