Recommended Zone Valves

I have a 1915 house in Pittsburgh with 3 floors with hot water heat. The house was converted in the 50's to an apartment on the 1st floor, and a second apt on the 2nd and 3rd floors. I have installed insulation in all of the walls, but I still do not get enough heat to the 2nd and 3rd floors, compared to the first. I believe this is because the radiators are much larger on the 1st floor, due to the fact that this was the area that was most used when the house was used as a house, with the 2nd floor being the bedrooms.

My question is: I would like to install zone valves on the individual radiators on the first floor, and want to know what are some reputable manufacturers. I understand these are to be installed on the return side, is this correct? I cannot break the floors into zones, as this would require redoing the piping in the basement(2 pipe system).

Thanks for the help.

 

contact honeywell they will be able to assist u