Boiler kettling is what occurs when your boiler begins to make noises that eerily resemble a kettle boiling water. While a kettle, by nature, is designed to boil water, your boiler shouldn’t. The hot water within a boiler should stay liquid as it makes its way around the system, heating your home quietly and efficiently without too much agitation. When kettling of a boiler takes place, it is because of water in your boiler heat exchanger boiling and vaporizing the water into steam. This forms steam bubbles that expand at a rapid pace and produce the characteristic rumbling, popping, or whistling sounds which indicate kettling. The noise might be some mild bubbling or even a loud banging or hissing sound which will not be easy to ignore or miss.
What Causes Kettling in a Boiler?
Knowledge of why kettling takes place in a boiler is vital to ensuring that it does not occur again. The three major culprits of boiler kettling noise are:
1. Build-up of Limescale
Limescale is the most widespread cause of boiler kettling, especially in areas of hard water. Hard water (high mineral-containing water) passing through your boiler heat exchanger leaves small amounts of minerals on pipe walls. These deposits over time create hard limescales that limit water movement through the heat exchanger. With limited flow, the remaining water becomes blocked and overheats, eventually boiling and producing steam which causes the kettling sound.
2. System Leaks
Leaks anywhere in your hot water system can potentially cause boiler kettling. When water leaks out of radiators, pipes, or the boiler, it lowers the overall water level in the system and admits air. This disrupts normal water flow, creating hot spots where the water has a chance to overheat and begin boiling. Slight leaks that don’t seem like much can cause problems with kettling in the long run.
3. Overheating Boilers
Faulty thermostats that don’t control temperature proportionally are the most common reason for overheating. Where a thermostat goes wrong, it may let the boiler heat water to unsafe levels. Clogged pipework that’s partially or totally obstructed is another reason for overheating that stops effective water movement through the system. In either instance, extra heat turns the water into steam vapor, which is causing those unmistakable kettling noises.
Recognizing the Symptoms of Boiler Kettling
Apart from the sound being obvious, there are a number of other indications that your boiler is kettling this includes poor heating efficiency; Radiators will take ages to warm up or fail to become as hot as normal. Another sign is unpredictable water pressure, with the boiler’s pressure gauge providing inconsistent readings.
Normal boiler shutdowns is an important symptom where your boiler will randomly switch off as a precautionary measure. Inconsistent heating where rooms become significantly warmer or cooler than others, with the final indicator being higher energy bills as kettling reduces efficiency, leading to increased energy consumption.
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Is a Kettling Boiler Dangerous?
Many homeowners wonder, “Is a kettling boiler dangerous?” The answer isn’t straightforward, as it depends on several factors including the age of your boiler and the severity of the kettling.
1. Instant safety issues
Modern boilers are made with advanced safety devices which usually make kettling an immediate danger. Such safety devices automatically cut-off controls which activate once temperatures rise above safety limits. Such precautions are not present in traditional boilers, and thus possibly dangerous.
The major safety risk of kettling is pressure build-up in the heat exchanger. Water expanding by as much as it boils up accumulates pressure that the system can fail to withstand. In worst-case scenarios, the pressure is strong enough to rupture internal pipework and thus leak steam and cause electrical hazards.
2. Long-term Damage Risks
Whilst kettling is not a risk at the moment, there is one important answer to the question “Will kettling damage my boiler?“: yes, it can. Chronic kettling places immense stress on your boiler components, especially the heat exchanger. The continual expanding and contracting through the creation of steam may lead to heat exchanger damage, as continuing kettling can result in cracking or deforming of the heat exchanger. Shorter life of the boiler due to the kettling stress causing deterioration of work internal parts.
It can also result in lower efficiency with mineral buildup and destruction decreasing your boiler’s efficiency in heating water. This all will come with an increased repair cost, with ignoring kettling typically resulting in costly repairs in the future. The boiler kettling repair cost is lower than ignoring the symptoms when you first notice them.Â
When to Act
It is agreed upon that while you can still use a kettling boiler in the short term, you must organize professional inspection and repair at the first opportunity. If you experience any of the following signs in addition to kettling, turn off your boiler right away and call a Gas Safe registered engineer:
- Leaks visible on the boiler
- Pungent gas smells
- Heavy steam or smoke
- Constant pressure loss
- Total failure of the heating system
How to Stop Boiler Kettling:
1. Power Flushing
Power flushing is usually the best solution for kettling that occurred due to limescale and sludge accumulation. Power flushing is done by forcing water through your central heating system to flush out rubbish, limescale, and corrosion. An expert 6-8 hour power flush can actually give your boiler a second chance on life. Power flushing costs between £300 and £800, which is very reasonable when compared to boiler replacement.
2. Chemical Descaling
For more serious limescale buildup, chemical descaling is required. Chemical descaling involves applying specialist descaling agents to your system to dissolve mineral deposits that can’t be addressed by power flushing alone. Professional descaling will restore your heat exchanger to near-original condition, eliminating kettling and enhancing efficiency.
3. Component Replacement
Worst-case scenarios, kettling damaged components that must be replaced. The most common replacements are:
- Heat exchangers (£300-£500+)
- Thermostats (£100-£200)
- Pumps and valves (£150-£300)
4. Prevention Measures
Prevention is better than cure. An annual boiler service by a Gas Safe registered engineer can identify and repair potential faults before they cause kettling.
If you are eligible through the ECO4 scheme, then ECO Boiler Grants will secure you with long-term warranty to help ensure that you are protected against costly repairs. Fill in our 1-minute simple eligibility form and get your new boiler today!
Improvements to Heating Available
The ECO4 scheme provides a full selection of heating improvements:
1. Boiler Replacements
Free boiler replacement of outdated inefficient boilers with new A-rated condensing boilers. This involves full fitting by Gas Safe registered installers and in many cases, replacement of other components of your central heating system, free of charge.
2. Heat Pump Installations
Air source heat pumps deliver cheap renewable heat without the need for a gas connection. They can save your energy bills substantially while delivering continuous, warm heat.
3. Central Heating Systems
Full central heating installations such as new pipework, radiators, and smart controls. This is particularly important to consider if your house uses electric storage heaters or old-fashioned heating systems.
4. Windows
Although ECO4 does not specifically include window replacement on an individual basis, it can be made in some instances if it is impacting energy efficiency significantly. Windows may be considered on a case-by-case basis as part of an overall energy efficiency package. If the EPC rating for a home would in effect make a substantial impact by fitting new windows, they can be funded.
Ready to see what ECO4 options are available to you? Our specialist team can quickly check if you’re eligible and walk you through all your options and funding available. Fill in our form to get started.
Why Choose ECO Boiler Grants for Your ECO4 Upgrade
When it’s a matter of securing ECO4 funding and ensuring a seamless upgrade, the right partner matters. At ECO Boiler Grants, we’ve established ourselves through being reliable, experienced, and dedicated to partnering with the UK’s most reputable energy companies.
With years of experience, we understand the ECO4 scheme inside and out. Our energy experts, with thousands of successful installations, are familiar with every aspect of the application process, obtaining funding, and the installation of your new heating systems. We keep abreast of all scheme amendments and legislation, so you can rest assured that you will receive accurate, up-to-date advice at every stage. Contact us to learn more now!
