What to Do When Your Radiator Suddenly Won’t Heat Up

Expert advice from Gulvin’s Heating & Plumbing Services in Herne Bay and across Kent

When a radiator suddenly stops heating up, it can quickly become uncomfortable, especially during colder weather. Sometimes the issue is simple and can be resolved at home, while other problems require the help of a qualified heating engineer.

In this guide, Gulvin’s Heating & Plumbing Services explain the most common reasons a radiator may stop working and what you can do to get your heating back on track.

1. Make Sure the Radiator Valves Are Fully Open

The first thing to check is whether the radiator valves are fully open. These valves can be knocked accidentally or may become stiff over time. The thermostatic radiator valve, usually shaped like a numbered dial, should be turned to its highest setting to allow heat to flow through. You should also look at the lockshield valve on the opposite side to ensure it has not been closed completely. If either valve feels stuck, it is better not to force it, as this can cause damage. A stuck valve is a common fault and may need attention from a heating engineer.

2. Bleed the Radiator to Release Trapped Air

If your radiator feels cold at the top but warm at the bottom, there may be trapped air inside it. This prevents hot water from circulating properly. To release the air, turn off your boiler so the water is not flowing. Then gently open the bleed valve using a radiator key. You will hear a hissing sound as the air escapes. When water starts to appear, close the valve again. Once the heating is turned back on, the radiator should begin to warm up normally. If you are unsure how to do this, Gulvin’s Heating & Plumbing can provide a professional heating system check and bleed your radiators for you.

3. Look for Cold Spots Caused by Sludge Build-Up

Another common issue occurs when a radiator is hot at the top but cold or patchy at the bottom. This often indicates the presence of sludge, a mixture of rust and debris that sits at the bottom of the radiator and restricts water flow. Sludge build-up cannot be fixed by bleeding the radiator and usually requires a professional power flush. This process uses specialised equipment to clean out the system and restore efficiency. Gulvin’s Heating & Plumbing offer expert power flushing services to tackle this problem effectively.

4. Check the Boiler Pressure

Low boiler pressure can prevent hot water from circulating properly around your home. Most boilers should show a pressure reading between 1.0 and 1.5 bar when the system is cold. If the pressure is lower than this, you can use the filling loop beneath the boiler to top it up slowly until it reaches the recommended range. After doing this, restart the boiler and test the radiator again. If the pressure continues to drop over time, the system may have a leak or an internal boiler issue that needs professional assessment.

5. See Whether Other Radiators Are Affected

If more than one radiator is not heating up, the problem may not be isolated. In this situation, the boiler might not be firing correctly, the heating pump could be failing, or the timer and thermostat settings may not be functioning as they should. When several radiators are cold, it is usually best to call a heating engineer, especially if you have already checked the pressure and valves without success.

6. Consider Whether Your Home Uses Heating Zones

Many properties in Herne Bay and the wider Kent area use zonal heating systems or smart thermostats. If only one zone is failing to heat up, the issue could lie with the thermostat, wiring, or a faulty zone valve. Gulvin’s Heating & Plumbing can diagnose and repair zonal heating problems and ensure heat is distributed evenly throughout your home.

7. When You Should Call a Professional Engineer

If you have tried bleeding the radiator, checked the valves, assessed the boiler pressure, and inspected other radiators without improvement, it is time to call a qualified engineer. Persistent problems, such as radiators that remain cold, valves that do not turn, recurring pressure loss, or widespread heating issues, need expert attention. You should also contact a Gas Safe engineer immediately if you smell gas or suspect a leak.

Gulvin’s Heating & Plumbing Services provide a full range of heating and plumbing solutions across Herne Bay, Whitstable, Canterbury and the surrounding Kent area. Their services include boiler repairs, boiler replacements, radiator repairs, central heating diagnostics, power flushing and emergency heating callouts. Their experienced team can quickly identify the cause of radiator problems and offer efficient, reliable repairs.

Fast, Reliable Heating Repairs in Kent

A cold radiator can be a sign of a simple issue or the start of a more serious fault. Whether you need help with a single radiator or your entire heating system, Gulvin’s Heating & Plumbing Services are ready to help restore warmth to your home.

Contact us and make sure your heating system is ready to keep you warm this autumn and winter.