Radiators play a crucial role in keeping our homes warm and cosy, especially during the colder months. However, like any heating equipment, they can develop issues over time.
One of the most frequent issues homeowners face is a radiator not heating up. When a radiator fails to heat, it can be due to multiple reasons, each requiring a different approach for resolution.
Understanding these common problems can help you diagnose the issue more quickly and decide whether it’s something you can fix yourself or if it necessitates a call to a professional.
Air Pockets and Trapped Air
One of the most common causes for a radiator not heating up properly is trapped air. Radiators work by circulating hot water through pipes, but air can sometimes get trapped inside. This trapped air can prevent the hot water from flowing evenly through the radiator, leading to cold spots.
Typically, this problem can be resolved by bleeding the radiator to release the trapped air. It’s a relatively simple process that involves using a radiator key to open a valve on the top of the radiator.
Sludge Build-Up
Over time, radiators can accumulate sludge, which is a mixture of rust, dirt, and other particulates. This sludge settles at the bottom of the radiator, obstructing the flow of hot water and causing the radiator to feel cold at the base.
Sludge build-up is often the result of corrosion inside the radiator or the presence of minerals in the water supply. Power flushing the entire central heating system can help remove this build-up and improve radiator efficiency.
Balancing Issues
Another common issue that can prevent radiators from heating uniformly is an imbalance in the system. Occasionally, one radiator might be heating up fine while others stay lukewarm or cold. This uneven distribution of heat can be caused by improper balancing of the radiator valves.
Each radiator has two valves – the thermostatic valve and the lockshield valve – and adjusting these valves can ensure a consistent heat level across all radiators.
Thermostatic Valve Problems
Thermostatic radiator valves (TRVs) are designed to adjust the temperature of individual radiators. However, they can sometimes get stuck or faulty, preventing the radiator from heating as required.
If the TRV is not functioning correctly, it can either keep the radiator too cool or too hot. Cleaning or replacing a faulty TRV can help restore the radiator’s normal operation.
Boiler Pressure Issues
The performance of your radiators is closely linked to the pressure in your boiler. If the boiler’s pressure is too low, it may struggle to send hot water through the heating system efficiently.
Regularly checking the pressure gauge on your boiler and ensuring it is within the recommended range can help avoid this problem.
If the pressure consistently drops, it may indicate a more serious issue with the boiler or the system that requires professional inspection.
Blocked or Partially Closed Valves
Valves that are partially closed or blocked due to debris can also result in ineffective radiator heating. Regular maintenance, including ensuring all valves are open and clear of obstruction, is essential for optimal performance. In some cases, simply opening a stuck valve can restore the radiator’s function.
Radiator problems are a common occurrence, especially in older systems. While some of the issues can be easily resolved with simple maintenance or DIY solutions, others may require professional attention. Regular inspection and maintenance of your heating system can greatly reduce the risk of encountering these problems.
If you’re experiencing a persistent issue with your radiator, it’s advisable to consult with a professional heating engineer to prevent further complications and ensure the continued efficiency of your heating system.
Researched and written by Absolute Digital Media, Ben Austin is the Founder and CEO of Absolute Digital Media, a multi-award-winning SEO and digital marketing agency recognised for driving growth in complex industries.
Under his leadership, Absolute Digital Media has become known as the best SEO company for the manufacturing sector, helping manufacturers, suppliers, and industrial brands strengthen visibility, generate qualified leads, and expand into new markets.
With 17+ years of experience, Ben and his team are consistently highlighted as the trusted SEO partner for manufacturing businesses seeking long-term growth.


