Why Are My Radiators Cold At The Bottom? January 14, 2026 When your radiators don’t heat up properly, it can make your home feel less comfortable and cause your heating system to work harder than it should. A common issue homeowners notice is when the top of the radiator feels hot while the bottom stays cold. This uneven heating is usually a sign that something is affecting the flow of water through your system. Understanding the most likely causes can help you decide when it’s time to call an expert for boiler repairs in Aberdeen and Stonehaven. Understanding What Causes Uneven Radiator Heating Radiators rely on hot water circulating evenly through the system. When that circulation is disrupted, parts of the radiator can remain cool even when your boiler is working. Ignoring the problem might not only make your home less comfortable but can also lead to higher energy bills and unnecessary strain on your heating system. After all, your boiler works harder to push heat through a system that’s not performing efficiently. Below are the most common causes behind radiators that are cold at the bottom and what can be done to fix them. 1. Build-up of Sludge or Debris Over time, small particles of rust and dirt build up inside your radiators, especially in older systems. This creates a thick sludge that gathers at the bottom, stopping hot water from circulating properly. As a result, the top of the radiator warms up while the lower section stays cool. While specialist system cleaning can sometimes be necessary, many issues can be resolved through targeted maintenance or replacing heavily affected radiators. 2. Air Trapped Inside the System Air pockets can get trapped in the central heating system, blocking the flow of water and causing uneven heat distribution. Though trapped air usually makes the top of the radiator feel cooler, it can also affect the overall circulation throughout your heating system. Bleeding your radiators is a simple process that often helps, but if air repeatedly finds its way back in, it could point to a larger issue such as a pressure imbalance or small leak that needs professional investigation. 3. Faulty or Stuck Radiator Valves Radiator valves control the flow of water into and out of each radiator. If a valve becomes stuck or blocked, the water can’t circulate freely, leaving certain areas colder than others. Thermostatic radiator valves can sometimes get jammed due to limescale or lack of use during the summer months. Gently adjusting or replacing them can often restore proper heating, but if the issue persists, a heating engineer can check whether the valve or pipework is causing the problem. 4. Circulation Problems from the Boiler If more than one radiator across your home is cold at the bottom, the cause may be linked to your boiler or the circulation pump. A failing or underperforming pump will reduce the flow of hot water, leading to multiple cold spots. Similarly, incorrect system balancing can mean that heat isn’t distributed evenly between radiators. A qualified heating engineer in Aberdeen and Stonehaven can ensure your boiler and pump are operating efficiently, restoring full performance to your system. 5. Poor System Balancing In some homes, particularly larger properties, certain radiators can heat up faster than others due to poor balancing. Balancing the system means adjusting each radiator’s valves so that hot water reaches every part of the home evenly. This is a straightforward process for a qualified engineer and can make a big difference to both comfort and efficiency. When to Call a Heating Professional If you’ve tried bleeding your radiators or adjusting valves but the problem continues, it’s a sign that something more serious could be affecting your system. A qualified heating engineer will be able to inspect the pipework, radiators, and boiler components to find the root cause. Prompt repairs can save you from higher energy costs, improve heating performance, and extend the lifespan of your system. Professional Boiler Repairs in Aberdeen and Stonehaven Westhill Boiler Services provides trusted boiler repairs in Aberdeen and Stonehaven, helping homeowners fix uneven heating and restore comfort throughout their homes. Whether your radiators are cold at the bottom, your boiler needs attention, or you’re struggling with inconsistent heating, our qualified engineers are here to help. We ensure every repair is carried out safely and efficiently, keeping your system performing at its best all year round. Call 01224 548803 or fill out our online contact form to arrange a visit today and get your heating running smoothly again.