Is This an Emergency?
If you can smell LPG gas (like rotten eggs), immediately turn off your gas supply (if possible) and evacuate everyone from the building. Do not turn on any lights, use torches, or use any naked flames.
Gas emergency line: 0800 111 999 — available 24 hours a day.
No Heat or Hot Water
Start with the basics: check that your thermostat is set to the desired temperature and heating mode, and verify the boiler is switched on. Check that the gas supply is not interrupted. If pressure is low, try repressurising using the filling loop — refer to your boiler manual before attempting this, and check for any leaks from radiators. If these steps don't resolve the problem, call a Gas Safe registered engineer.
Boiler Making Unusual Noises
Occasional gurgling or crackling is normal. However, loud banging, kettling (a whistling or rumbling sound), or persistent noise indicates a problem. These issues often relate to sludge build-up in the system, low water pressure, or air in the pipes. Do not ignore persistent unusual noises — call an engineer to investigate.
What is Kettling?
Kettling sounds like a boiling kettle inside your boiler. It is usually caused by limescale or sludge on the heat exchanger restricting water flow and causing localised boiling. A Gas Safe engineer can diagnose and resolve this.
Water Leaking from the Boiler
Never ignore a water leak. Do not attempt repairs yourself. Turn off the boiler and call a Gas Safe engineer immediately. Leaks may originate from loose joints, corroded pipes, a faulty pressure relief valve, or internal component failure. The engineer will identify the source and repair or replace affected components.
Pilot Light Going Out Frequently
Some older boilers have pilot lights that occasionally blow out if a draught is present. Check that nothing is blocking the boiler combustion area. If the pilot light goes out frequently, or if you smell gas, notice unusual odours, or see yellow flame colouration (it should be blue), do not attempt to relight it. Turn off the boiler immediately and call a Gas Safe engineer.
Yellow Flame Warning
A yellow or orange flame instead of blue indicates incomplete combustion, which can produce carbon monoxide. This is a safety hazard — do not use the boiler and call an engineer immediately.
Frozen Condensate Pipe
Modern boilers have a condensate pipe (usually a white plastic pipe leading outside) that removes acidic water produced during heating. In severe cold, this pipe can freeze, causing the boiler to lock out and stop producing heat. You may see an error code on the boiler display.
If the condensate pipe is accessible and clearly frozen, you may carefully pour warm (not boiling) water over the frozen section. However, if you are uncertain about which pipe is affected or it is inaccessible, call an engineer. Once resolved, insulate the pipe to prevent recurrence next winter.
Low Boiler Pressure
Most boilers require a pressure of 1 to 1.5 bar when cold. If your pressure gauge shows below 1 bar, the system may need repressurising via the filling loop — a procedure described in your boiler manual. If pressure drops repeatedly, this may indicate a leak in the system, which requires professional attention.
Radiators Not Heating Evenly
If radiators are cold at the top but warm at the bottom, this is usually caused by trapped air. Bleeding the radiator with a bleed key will resolve this. If radiators are cold at the bottom but warm at the top, the issue is likely sludge build-up — a power flush by a heating engineer may be required.
🔧 Boiler Inefficiency Costs You Money
An older or poorly maintained boiler uses significantly more LPG for the same heat output. Use our calculator to see how your boiler age affects your running costs.
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