Loud banging or knocking noises coming from your boiler can be alarming, especially if it starts out of nowhere. While it may not always signal a major fault, ignoring these sounds could lead to more costly repairs or even a complete breakdown. Here’s what you should check before calling out an engineer.
Common Causes of Banging Noises in Boilers and First Steps to Take
If your boiler starts banging, clanging or making kettling-like sounds, it’s likely reacting to internal issues with water flow, pressure, or limescale. Acting early can often save you time and expense.
Bleed Your Radiators
Trapped air is a common cause of knocking pipes and radiators. Use a radiator key to release air from the top of each radiator, starting from the ground floor upwards. If air comes out before water, you’ve successfully found a culprit.
Check Your Boiler Pressure
Low pressure can cause banging and rattling, particularly when the pump is working harder to circulate hot water. A healthy boiler pressure reading is typically between 1 and 1.5 bar. If it’s too low, refer to your manual to safely top it up.
Listen for "Kettling"
A loud rumbling or whistling sound like a kettle boiling could indicate limescale buildup on the heat exchanger. This is especially common in hard water areas like Chelmsford or Saffron Walden. While it may require a powerflush or descaling treatment, turning the boiler off and back on can sometimes reset the system temporarily.
Check for Loose Pipes
If the banging happens when your heating system starts up or shuts off, expansion and contraction in metal pipes may be causing them to knock against floors or walls. Inspect visible pipework and secure any loose areas with brackets or insulation.
Ensure the Pump Isn’t Stuck
Boiler pumps circulate water around your system. If the pump is seized or faulty, it may create loud clicking or banging noises. You can gently feel the pump for excessive heat or vibration, but don’t attempt to open or service it yourself.
Don’t Ignore Persistent Noises
If the noises continue after basic checks, it’s best to book a professional inspection. Ongoing banging can signal deeper issues like pump failure, sludge buildup, or system imbalance that require expert intervention.
Banging boiler in Dunmow, Bishops Stortford, Saffron Walden or Chelmsford?
He@Heating Limited provides professional boiler fault diagnosis and repair services across Essex. Call 07956575049 or fill out our contact form to arrange a boiler check today.
