Posted by Harold Kestenholz - Hydronic Network on October 19, 2001 at 11:26:56:
In Reply to: Weil McLain posted by Jack on October 18, 2001 at 20:50:05:
While your radiators only require 500Mbtuh, the radiators will only need that much after they and all the pipes are heated up. If you only provide enough heat for the radiators the burners may not stop firing for many days until the pipes heat up, increasing fuel bills without satisfaction. Even then the pipe losses may be high enough so the burners are on all winter without enough input; leaving some rooms warm while others remain cold. A steam boiler replacement must allow for piping and pickup allowance which may be more or less than an additional 50 percent over your radiator requirement.
Manufacturers make boilers that overlap from one size range to another while the series cover smaller or larger ranges of input.