Sizing a new boiler to old radiators

stevelaw

I have an oil-fired steam boiler (cast iron radiators) that's about 50 years old and operating inefficiently but with no trouble.  I have been advised to get a new boiler.  I have heard that in the case of steam heat it is more advisable to size the boiler to the existing radiator system.  How is this normally done?  This is a three story building with basement with a 50' x 35' footprint (ten foot ceilings), full underground basement, blown in insulation in attic, insulated on first floor but just plaster and lath on the second and third stories.  The original boiler has a 472Mbtu/H plate on it.

BobC

sizing a boiler

Steam boilers are usually sized so the EDR (total area of all radiators) is equal to or less than the boilers Sq Ft of steam rating on the name plate. You generally need enough stem to fill all the radiators (or convectors) but you don't want to much more because that leads to short cycling which drives up fuel costs.



This chart will help you determine the sq footage of each section in your radiators. A section consists of a number of tubes or columns that are connected together, these sections are then connected to each other to make up the radiator.



Bob

BobC

PDF not loading

For some reason the Boiler Sizing.PDF chart did not load. Lets try it one more time-



Bob

Rod

Boiler Sizing Chart

BobC- Is this the one you want?

- Rod

BobC

File

Thanks Rod, for some reason I could not get that same file to load with my post.



Bob