Random Radiators Not Getting Hot (But Have Water)

PerrottaMechanical

Installed some new cast iron baseboard in an older home getting a full renovation. We added a total of about 6 sections on the first floor, in conjuction with the existing traditional radiators. This home has rads going up to the 3rd floor.

Filled system and bled all radiators throughout home, after bleeding topped pressure off at about 17-18 PSI before firing up. After firing boiler we went around and found 3 radiators not getting hot (all others are heating fine).. one section of the new baseboard on the first floor, one of the traditional rads on the second floor along with one on the third floor, all ice cold. Went ahead and kept bleeding each rad that wasn't getting hot and can say we took a total of about a gallon or two out of each. Still cold.

Boiler is piped with circ on the supply side, newer expansion tank and spirovent, Boiler has a single Taco 007 Circ for the entire system. house is probably about 2500 sq ft with big radiators throughout first floor to third along with the baseboard we installed. Boiler size is 120k BTU input. Which is probably undersized..

Im struggling with the fact that its one rad on each floor and i have steady water flow out of each one.

Going back in a couple weeks to try to workout this issue and would really appreciate any insight or thoughts on the situation we are dealing with.

Thanks in advance everyone!!