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Cold Spots On Your Radiator? Here is How to Resolve That Issue

A photo of a cold radiator

The primary function of a radiator is to heat the room it’s in. Naturally, if you notice something’s wrong with the room’s temperature, you check the radiator first. The most common problem is cold spots on the radiator, whether on the bottom or on the topThese so-called ‘cold spots’ occur when there’s an obstruction preventing the water from flowing inside the radiator. The places it doesn’t reach are left unheated.

There are two reasons those spots appear and in this article, we will talk about the problem and how you can fix it.

Why are Radiators Cold at the Bottom?

Built-up sludge and debris are the most common reasons for making your radiators cold at the bottom. The filth prevents the proper hot water circulation inside the radiator and leaves cold patches at the places it doesn’t reach.  Rust, hard water, limescale, and others can build-up inside of the radiator and create an obstruction for the water flow. You shouldn’t ignore the problem because it can lead to boiler or heating system damage. 

To fix this issue, perform a power flushing of the radiator. This task requires some preparation, but also knowledge and understanding of how the heating system or boiler works. Plus, based on the type of radiators you have, it can be a back-breaking task for you since you may need to lift the radiator. 

Why is a Brand New Radiator Cold at the Bottom?

Since it’s a new unit, it cannot have any build-up inside. There can be several other reasons for this issue. 

  • It could be a circulation problem, airlock or a faulty valve
  • Blockage in the pipes.
  • A radiator balancing issue

If your radiator is hot at the top and cold at the bottom, you may need the help of professional radiator installers, regardless if it’s a new or an old unit.

Why is Your Radiator Cold at the Top?

Radiators that are cold at the top and hot at the bottom often have air inside of them. The air rises to the top and the hot water remains at the bottom of the radiator. That’s why in this case, the cold spot is on the top. This problem is easier to fix than the above-mentioned one. 

Fixing this issue requires you to get the air out of the radiator, and this process is called ‘bleeding’. So, if you hear or read about ‘bleeding a radiator’, this is what it means.

Your Radiators are Cold in the Middle?

The reason your radiators are cold in the middle is once again sludge build-up. Like we said already, there are various things that can cause build-up inside of radiators and you need to flush their insides thoroughly. Power flushing is your best bet in this case.

How to Fix a Cold Radiator

Now that you know all the possible reasons you’re experiencing radiator cold spots, it’s time to learn how to fix your issue. There are several cold radiator fixes, some of which we mentioned already. Also, some of these fixes you can do on your own, with no professional help. So, here are the 4 cold radiator fixes:

Bleed your radiators

Bleeding a heating system is necessary when your radiators aren’t working properly. This means that you may have to bleed radiators whether they are hot or cold. Sometimes the air is an enormous problem, and some or all radiators may become too hot. Then bleeding them is also a must. 

By bleeding the system, the trapped air disappears, returning the normal water flow in the radiators. It is possible to DIY radiator bleeding if you prepare well.  If the radiator is not getting hot even after bleeding, then try one of the remaining fixes or call a heating expert to fix the issue.

Perform a Powerflush

You might be wondering what radiator power flushing is? It’s a procedure that is carried out in your home using a specialist pump. The procedure is a must if you want to resolve problems with the central heating or when a new boiler is being fitted.

We recommend only a licensed specialist to carry out the power flushing at your property, for your peace of mind.

Balance your radiators

Balancing radiators is an important aspect of the installation process. Balanced radiators will heat evenly and produce their optimum heat and, thus, heat up rooms faster and more efficiently. A simple way to track down the performance of your radiators is to attach thermometers to each one. However, some homes are too big and the radiators are far from the heating system or boiler. In this case, it is acceptable to expect a colder unit.

To balance your radiators, you need to:

  1. Turn off the heating and radiators and wait for at least two hours. 
  2. Measure the flow differential. It should be of at least 20°C at the boiler.
  3. Measure whether the return temperature is below 55°C.

If you get results of the flow differential being less than 20°C or the return temperature is higher than 55°C, then the system is most likely unbalanced. You’ll need a professional heating engineer to fix it.

Get a flow diverter installed

A flow diverter is not a necessary part for all radiators. However, you can’t always find it with your new radiator unit. That happens because the manufacturers may forget to install it or convince you it isn’t a must-have. 

A flow diverter helps water flow through the radiator in the right direction, thus making it evenly hot from top to bottom. Talk to a heating specialist about installing a diverter in your radiators to get rid of cold spots.

Key Takeaways

To sum up, after the installation of a heating system, ensure your tradesman checks all radiators before leaving your home. If, after some time, you sense these cold spots on radiators, determine the severity of the problem. Is it on all radiators? Is it on top, bottom, or centre of the radiators? 

Fixing the cold radiator by yourself only if you feel confident enough in your skills and knowledge. Remember to call your heating engineer in the following situations:

  • Radiators are not getting hot even after bleeding or balancing;
  • Your heating system needs a powerflush;
  • You deem the job too complicated to DIY;

Cold Spots On Your Radiator? Here is How to Resolve That Issue

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