The answer to 'boiler making loud noise' is that a noisy boiler is often caused by sediment buildup, low water levels, or a faulty component. The most common symptoms are banging, rumbling, or whistling sounds coming from the boiler. Solutions can include flushing the system, refilling the water, or replacing worn parts.
If the noise is severe or persistent, it's best to call in a professional HVAC technician to diagnose and fix the issue. Attempting DIY repairs on a boiler can be dangerous and may cause further damage if you don't have the proper expertise.