replacing one or two of six radiators in one unit of a 90-unit building circa 1925 with steam heat.

pross

I have a classic six in a 1925 co-op in NYC. I now have six active original radiators and want to replace at least one or two of them with thinner units that will hug the plaster/masonry/brick wall and be thinner to give me floor space. Shape flexible, but it must use existing steam in/out connection. I'd like to have better valve control so a really efficient and long-lasting heat sink is good. To optimize function retention and am willing, e.g., to add a heat sink, use iron replacement units, or make the units longer so the central heating isn't defeated; maybe a locally controlled boost? I saw one unit that goes up the wall. Your valuable advice is requested.

pross

Better valve control is mainly to prevent overheating but also to increase during periods of less steam or very cold weather.