My house has what I believe to be recessed Sunrad hot water radiators. Built in 1936, with most of the rooms having these recessed radiators, I am trying to figure out how to count the number of sections. My ultimate goal is to replace the existing 1936 boiler (originally coal, now oil and in the future, I hope, a natural gas fired modulating condensing boiler). I want to change some of the zones (adding a third floor zone and separate the first and second floor zones) which will require some piping changes and additional pumps.
I want to figure out the existing radiation for flow and pumping reasons (I've done the heat loss calculations already). It is just not intuitive to me how the number of sections is figured with these radiators. I've tried to post a picture from the internet of what looks like my radiation.
Thanks in advance for any help (and congratulations to the new grandfather).