Thermostatic radiator valves

[Amy A.]

Has anybody used thermostatic radiator valves to save money in old apartment buildings heated with steam radiators? I'm considering the purchase of such a building and am trying to figure out a way to reduce the gas bill. It already has a new gas burner, but the steam boiler itself is old. I would consider replacing the entire system, but the pipes are wrapped in asbestos and it would be very expensive. it's 3 stories and there are 12 units.