Heating for Chicago multi units: space heater?

[Peter Graves]

Hi BP, first time poster. Am looking at a 2 flat currently that has a heating situation I haven’t run into yet, and would like your thoughts. The units are each heated by individual self-contained  space heater/ furnace units in the main living area. These units are the only point source of heating for the entire floor and I’m a bit concerned the heating isn’t going to be uneven/uncomfortable for thetenant. Have others had successes or horror stories with these? It is a very old building, well kept though. Would love some opinions for this TX guy who hasn’t had to deal with heat for much of his lifetime. Thanks!