Whistling Radiators

We recently had our boiler replaced (steam heat) and since then many of our radiators are whistling when the heat goes on, especially at night. Not too loud, but just loud enough to wake up our 2-year-old. So we need to address it. Does it sound like a problem with the valves (that’s where the whistle comes from)? Or something worse (I shudder to think…)?

Thanks.

By lah |