Top 10 Boiler Issues: Troubleshooting & Fixing


Boiler issues can become a real headache, especially in the winter season. Some of the times, the problem can be avoided and other times, it just cannot. Even if your boiler is new, it can still get subjected to issues like leaks and cold radiators. If the issue gets big, you can contact a Gas Safe Engineer to help you troubleshoot and solve the problem.

Most of boiler issues are very common to identify and can be easily fixed by you. You just need proper guidance and assistance. To help you out, we have sorted out a list of the top 10 boiler issues and we have listed their easy fixes and solutions.

Top 10 Boiler Issues:

  • Unusual and loud noises from the boiler
  • Leakage in the boiler
  • Low boiler Pressure
  • Radiators getting cold
  • Water not getting hot enough
  • Boiler not responding to the thermostat
  • Pilot light not responding
  • Boiler kettling
  • Boiler not turning on – power
  • Frozen Condensate Pipe

Unusual and Loud Noises from the Boiler

Boilers often produce a sound of a low hum, and that is completely normal. However, if this sound gets louder and stronger then this is a matter of serious concern. Strange and loud noises can be heard from the boiler if it is experiencing any issues.

Any obstacle or hindrance in the pipe can cause these noises. Under these circumstances, sounds of whistling, gurgling, whooshing, and humming can be heard. This would mean that air is trapped in the boiler pipes. You will need to locate the frozen pipe and fix the noise. Drone noises can also come in case of any fault in the boiler pump. Bleeding the radiator can also solve this issue.

If the issue still occurs and strange and unusual noises are still coming from your boiler, we would advise you to immediately call a gas-safe engineer to troubleshoot the issue and remove the obstacle if it is in the boiler pipes. A qualified heating engineer or technician would inspect and diagnose the cause of unusual and loud noises to provide solutions such as bleeding, descaling, repairing, replacing, or adjusting settings.

Leakage in the Boiler

Leakage is one of the most common issues with the boiler. It seems to be a very minor problem at first, but please do not ignore it! Over time, it can become very hectic and cause a lot of trouble. Along with the water damage in your house, it can damage things around the boiler such as electrical switches, wires, plugs, etc. It can also become a source of mold and fungi in your home, which is bad for air quality.

Corrosion, improper water line connections, too much pressure, a broken seal, or a damaged valve or pump are some of the most common causes of leaks in a boiler. Poor boiler installation can also be a problem for leakage. These issues must be addressed and taken care of before the leaking boiler causes a lot of damage.

leakage in boiler - top 10 boiler issues
Top 10 Boiler Issues: Troubleshooting & Fixing 3

If corroded boiler pipes are an issue, an easy fix is to replace them with new ones. But we never advise you to take care of this issue alone. Rather we insist on calling out a certified gas-safe engineer who can help you diagnose the issue and take care of this problem.

Low Boiler Pressure

Low boiler pressure is a common problem faced by homeowners with central heating systems. It can lead to reduced heating performance and even complete loss of heat. It can be caused by water leaks, bleeding radiators, or pressure relief valve issues. Understanding the underlying causes and knowing how to address them promptly can help restore optimal heating comfort.

Another reason for the low boiler pressure problem can be a leak in the boiler or the radiator. Locate the leaking region in the boiler and call an engineer to fix it. Fixing the leak will help to restore the boiler pressure.

Other fixes for this specific problem may include repressurizing the boiler by locating the filling loop and opening the valves slowly until the pressure gauge reaches the recommended range. In case of repeated concern, the best solution is to consult the boiler’s manual or contact a professional if unsure. If the pressure loss is recurrent or unexplained, have a gas-safe engineer inspect the system thoroughly.

Radiators Getting Cold

When the radiators in your house begin to feel cold, it may be an annoying and uncomfortable experience that interrupts the overall comfort of your home. The problem of having cold radiators is a prevalent one that may be brought on by a number of different causes. There might be airlocks inside the system, a buildup of sludge, defective thermostatic valves, or even issues with the boiler itself. These are all possible causes.

As these causes may seem very much hectic and troubling, they do have very common and easy fixes. Below, we have compiled a table for you to understand the most common issues due to which the radiator gets cold and experiences problems and we have also provided their solutions and easy fixes. So, get your tools up and get ready to fix the issue yourself.

Common Issues with the RadiatorCommon Fix
Trapped air in the radiatorBleed the radiator
Faulty thermostatic valveCheck and adjust the thermostatic valve
Low boiler pressureIncrease the boiler pressure
Sludge or debris buildup in the systemPower flush the central heating system
Open or leaking valves in the systemInspect and fix any open or leaking valves
Issues with the central heating systemConsult a professional heating engineer
Table showing some common issues with radiators and their common fixes.

If your radiator is experiencing any other issue than these listed above, the best possible solution is to call a gas-safe engineer immediately and get your boiler fixed.

No Hot Water and Heating

People install boilers in their houses to get hot water and a central heating system, but when the boiler faces an issue working, it does not provide hot water and a heating facility. People usually come across the fact that their boiler is experiencing this particular issue when they are taking a shower, and this problem really gets frustrating in winter. In such situations, you would only want your boiler to get fixed as soon as possible.

There can be many possible reasons for this problem. The most common issues are malfunctioning pilot lights, frozen pipes, a faulty diverter valve, faults with the thermostat, or even pressure issues with the boiler itself.

Now, let’s look at easy fixes for these problems. If your issue is with the pilot light, we would advise you to relight the pilot light or replace a faulty thermocouple. Similarly, you can try to thaw the frozen pipes in case of a frozen pipe problem. Calling a certified gas plumber is also a good option in this case. If the diverter valve has any fault, try replacing it. You can do the same fix for a faulty thermostat in the boiler.

water not getting heated in boilers - top 10 boiler issues
Top 10 Boiler Issues: Troubleshooting & Fixing 4

Boiler Not Responding to Thermostat

Homeowners have a variety of thermostat options to select from, which can help them make their houses more energy efficient and smart in this manner. However, if the boiler stops reacting to the thermostat, it can become an annoying problem that needs to be fixed. If your boiler does not react in any way to the temperature set on the thermostat, the controls may either be faulty or very old.

To check if the thermostat is functioning properly, check to see if the temperature shown on the thermostat is higher than the temperature in the room at the moment. If the temperature in the room is lower than the setting set on the thermostat, consider changing the batteries. If this does not work, the thermostat may need replacement.

Some other common fixes may include moving the gadget closer to the boiler and inspecting it for any interference that could be the source of the problem. In the event that the issue with your thermostat continues, you should consult the instruction manual for guidance or get in touch with the manufacturer for assistance.

Pilot Light Not Responding to the Boiler

The pilot light is one of the main components of a boiler. The pilot light is a little gas burner that produces the first flame required for the boiler to begin generating heat or heating water. If it undergoes any issues, the boiler will not work properly.

Frequently occurring issues with malfunctioning pilot light may include:

  • Faulty thermocouple
  • Gas supply issues
  • Blocked pilot orifices
  • Air in the gas line
  • Malfunctioning gas valves

When you are attempting to reignite the fire, again check to see if there are any problems with the gas supply. In the event that the gas valve is turned on but the boiler still does not get gas, this is an indication that you need to get in touch with a professional. You also have the option of relighting the pilot light by yourself by referring to the instruction manual and following its instructions.

Boiler Kettling

Boiler kettling sounds like a kettle boiling. Limescale or sludge on the heat exchanger restricts water flow and overheats. This reduces efficiency, damages the boiler, and requires expert repair.

In simpler words, boiler kettling happens when water is heated too fast and hits the boiling point. This makes steam and traps air. The trapped air makes a sound like a kettle whistling. Boiler kettling is one of the most commonly faced problems by homeowners that have a boiler.

Reasons for boiler kettling issue includes incorrect water pressure, limescale buildup, sludge or debris accumulation, incorrect thermostat settings, and inadequate circulation. Boiler kettling can easily be fixed by you with little understanding of the problem. If you are experiencing this issue, we advise you to check the boiler pressure. On other occasions, examine and fix pipe obstruction issues. Also, try to descale the heat exchanger or use a descaling agent in case of limescale buildup.

If all of this goes over your head, don’t take any stress. Simply call a gas plumber to come to your house and fix this boiler kettling problem so your boiler stops whistling like a kettle and works as new.

Power Issues – Boiler Not Turning On

Boilers can lead to frustrating issues if left unserviced for a long period of time. There can be many reasons for this problem to occur. The common ones are trapped air, low or high boiler pressure, a faulty thermostat, and an accumulation of debris and sludge in the pipes. If your boiler keeps switching off, the above-mentioned factors can be the reason for it.

To resolve this issue and fix it, we recommend you to check the pressure and thermostat settings. Also, try to check if the air is being trapped or not, and if it is, then try checking the possible reason for it. If any of these suggestions do not work, call a registered boiler engineer to troubleshoot the problem and fix it.

Frozen Condensate Pipe

If you have a condensing boiler, you know that it produces a byproduct called condensate, which must be drained away from the building. This condensate line occasionally freezes in low conditions, creating noise inside the pipes. Thankfully, a frozen condensate pipe is usually indicated by a problem code on newer boilers.

Safely thawing a condensate pipe may be done with the help of internet instructions and watching online tutorials mostly available on YouTube. If you don’t feel comfortable or confident thawing your condensate line on your own, it’s best to call a licensed professional. The boiler engineer will definitely assist you in fixing your frozen condensate pipe.

YouTube video
Youtube Tutorial showing how to defrost a condensate pipe – Which?


Boiler issues might frustrate. Leaks, chilly radiators, and non-responsive thermostats are frustrating. With the appropriate instruction, many common boiler issues may be recognized and rectified without a Gas Safe Engineer.

Homeowners may solve problems themselves by learning typical difficulties and remedies. To optimize performance, bleed radiators and fix low boiler pressure. To help you to further, we wrote down the most common and top 10 boiler issues, and how you can fix them. However, serious difficulties like leaking or a frozen condensate line need expert assistance. Therefore, it is always advised to call gas-safe engineers for professional solutions and troubleshooting.

If you want professional and efficient support, Clean Heating Ltd. is the way to go. Trust our boiler repair experts. Schedule a service or check out our service plans to end frigid evenings and unpleasant breakdowns.

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