Correct Capacity for Oil/steam boiler

bosfmv

I need to replace my oil fired tank-less steam boiler.  I heat the main house with steam and have a three room addition that is heated through the same boiler with forced hot water.  I have received several quotes on a replacement, however, I am concerned that the capacity (IBR sq ft ratings) vary from 513 to 700 sq ft.  My present boiler has a capacity of 760 sq ft?  Apparently there is a formula based upon the number and size of the steam radiators in the house.  Does anyone know what that formula is so I assure I replace with an efficient system?

Jamie Hall

There is indeed such a formula

in fact, a residential steam boiler is sized entirely based upon the effective square feet of radiation, plus what is called the pickup factor.  In your case you will need to add some capacity for the hot water loop as well.



What is needed is to find out what the "EDR" rating of your radiators is, and add them all up.  Then multiply by the pickup factor, which is usually in the range of 1.33 to 1.5, but can be more if, for instance, someone took all the insulation off the steam mains and didn't put anything back.



It sounds as though you might be interested in learning more about your heating system -- which I encourage!  If so, I suggest the three books offered as a package deal ("A Steamy Deal") on this site; they are well written, highly informative, amusing -- and will help a lot!

Unknown

Measuring for a new Boiler

I agree with Jamie. Get the books as they have all the formulas you need and explanations as why things should be installed a certain way.

Here 's a link to "A Steamy Deal"

http://www.heatinghelp.com/products/Super-Deals/14/129/A-Steamy-Deal

The books will save you many times their cost and more during the installation of your new boiler plus reduce a lot of headaches.

Here's also a chart which maybe of help to you

http://www.ecrinternational.com/secure/upload/document/414.pdf

- Rod