Welcome! Here are the website rules, as well as some tips for using this forum.
We are in the process of sizing a boiler replacement for a 1921 school building (now a community center). Presently
has a coal fired 2 pipe steam system from around 1950. Problem is finding EDRs for convectors and fan coils. Have gone through Dan's book "Every Darn Radiator" and did not find them. We will start with the convectors. The enclosures measure 5" deep by 15" high. Inside they are made from 2" steel pipe with 4" square fins, and range from 3.5 ft double row to 27ft single row. Pictures below.

0 ·
Comments
Any make and model numbers? Might get lucky and find an old cut sheets for a similar but newer version.
Other option is to take some measurements of the pipe size, fin spacing, # of rows and some pictures and maybe see if Trane or Modine might help you out. Tell them you want to price some replacements for budgeting.
http://beacon-morris.com/modules/lit_lib/download.asp?litFileID=1688
"Reducing our country's energy consumption, one system at a time"
Steam, Vapor & Hot-Water Heating Specialists
Oil & Gas Burner Service
Baltimore, MD (USA) and consulting anywhere.
https://heatinghelp.com/find-a-contractor/detail/all-steamed-up-inc
brazed on 1" steel headers. See pics.
Division
"Reducing our country's energy consumption, one system at a time"
Steam, Vapor & Hot-Water Heating Specialists
Oil & Gas Burner Service
Baltimore, MD (USA) and consulting anywhere.
https://heatinghelp.com/find-a-contractor/detail/all-steamed-up-inc
Picture of fan coil tag below.
Go to either ecomfort.com or go to the Modine website for the performance data of their units for correction factors.