A hot-water central heating system consumes 14 to 25 per cent of your home’s energy, according to the U.S. Department of Energy. Keep your system well maintained so the energy doesn't go to waste. If your system makes gurgling or banging noises, you may have air trapped in the hot-water pipes. Air bubbles prevent water from passing correctly through the system, causing inefficient operation that may stop radiators from heating up. Removing air from the system is relatively simple as most systems are fitted with air bleeder valves.
Search for your central heating system’s air bleeder valve. These are usually fitted directly on top of the boiler tank or below the boiler attached to the tank’s hot-water pipes.
Place a bucket beneath the bleeder valve and undo it with the valve key, turning it 1/4 turn until air escapes from the system. Wait until water spurts from the valve; at first, air and water will be mixed and will escape with a fizzing sound.
Close the bleeder valve with the valve key once the water has started to flow evenly. Dry the valve with a rag and check that it is not leaking; tighten if necessary.