Why Your Radiator Has Cold Spots

Homeowners can sometimes discover cold spots on their radiator, they usually try to ignore this problem or try to fix it by turning the thermostat up. Turning the thermostat up and ignoring the problem is not the solution, by doing this, they can cause serious damage to their heating system. There can be many reasons that can cause cold spots, some of the reasons are mentioned below, along with the solution to overcome them.

radiator with cold spots

Reasons why your radiator has cold spots


When your radiator is cold from the bottom, you should immediately check if there is a development of sludge and debris in it. This build-up is usually a mixture of limescale, old dirty water and rust, which forms into a thick combination of sludge that stops the hot water from circulating all around the heating system and causes cold spots.

This build up should be cleaned properly, or it can create some serious problems for your boiler as well. The sludge and debris can be cleared by a power flush which is performed by a heating engineer. Make sure to call a heating engineer immediately and book an appointment for a power flush to save yourself from further disturbance


Radiator valves are an element of water-based radiators, their purpose is to control the temperature. The valve’s job is to change the hot water flow that runs through the radiator, which keeps it warm and heats the room. The valve usually switches off in summer and switches back on in winter. But this process of switching off and on seizes the valve and it gets frozen which keeps the radiator from warming up. Homeowners usually suppose the fault is in the radiator but the problem is actually in the valve which is a lot cheaper to repair. You can try to fix it yourself by following these simple instructions:

- Turn the locking nut to fix the thermostat

- The pin is usually pushed in if it is stuck, try to find it.

- Use a spray to clean the rust or dirt on the area

- Try to release the pin by putting pressure on it with the help of a small flat metal piece.

If it continues to stay frozen and does not perform, then call a heating engineer as there may be some other issues involved that can be causing this problem.


When a heating engineer installs a heating system on your property, they makes sure to balance all the radiators equally so that they heat up evenly. To make sure the radiator is working properly and producing enough heat there should be a thermometer on one side of the radiator to measure the heat. If a radiator is not balanced, it will not heat up quickly and the property owner will start to notice cold spots on it.


An airlock can cause circulation problems in your radiator. Heated water travels through our heating system to our radiators which keeps your house warm but warm water can produce an overflow of water vapour which can cause an airlock.

How can you find out if there is an airlock?

Well, if your radiator has cold spots and remains warm from the bottom, if your pipes are making gurgling noises or if your taps are sputtering instead of flowing smoothly, you should know there is an airlock that needs supervision. You can solve this problem by bleeding the radiator, which will help release all the trapped air inside. If you do not know how to bleed your radiator contact a heating engineer.

Get in touch with us

If you are looking for a heating or gas engineer to help you fix your heating system or if you want to install a new heating system get in touch with us today by calling us on 01952300008.

Ready to book a service plan?

Our friendly, professional team is here to help. Tell us how we can assist you, and we'll be in touch shortly!
Thank you! Your submission has been received!
Oops! Something went wrong while submitting the form.