Posted by Harold Kestenholz - Hydronic Network on July 10, 2001 at 19:34:43:
In Reply to: How do I determine the right size steam boiler posted by Bill C. on July 10, 2001 at 16:57:51:
As this is a steam system, your plumber is correct. Steam must fill the entire steam system and heat the existing pipes as well. A boiler that is too small will run continually trying to fill the system to no avail, so heating only a protion of the system, and that portion may change without solution. It is simpler to get a gas steam boiler with the same input as the oil burner. A gas strip burner is not variable like an oil burner, so it has to be right from the installation.
To size the boiler, you can count the sections of radiators and find their total output, then multiply that total by 1.5 to take care of the pipe and pickup allowance of the sytem. Instructions how to do so are at http://www.hydronic.net. A calculation program for the heat loss of the building is there also, but it would be most relevant if you changed the system to water from steam.