Why Is My Radiator Cold at the Bottom?

We all want to feel warm and cosy during the harsh winter months, right? But what if one day you wake up and find your radiator is cold at the bottom and your heating bills are on the rise? What could the problem be? Has your central heating system failed you?

A cold radiator is always unpleasant. Luckily, we know the culprit behind your cold-bottomed radiator – sludge. In this blog post, we will go over why the bottom of your radiator is cold, what sludge is, and how to deal with it effectively.

So, if this sounds like you:

• Your radiator is hot at the top and cold at the bottom;
• You’re struggling to fix it or are looking for the reason;
• You want to know what to do if your radiator is cold all over,

Then read on! This post is for you.

Why is your radiator cold at the bottom?

All radiators will be slightly cooler at the bottom than they are at the top since heat rises up. So, if this is the case, you don’t need to worry. However, if one or all of your radiators have cold spots at the bottom, then there is an issue.

If the bottom of your radiator is cold, that indicates there is a build-up of sludge inside. This mostly happens to older radiators, as it takes some time for it to form. Sludge is the result of internal corrosion and an accumulation of dirt inside the heating system.

The dirt particles mix with the rust and water, forming a sludge that settles at the bottom of your radiator. This obstructs the flow, forcing the hot water to go straight to the top, leaving the bottom of your heater cool.

A build-up of sludge can cause your radiators to be less efficient when heating your home, increasing your energy bills. It may even damage your central heating system if the corroded particles are allowed to roam around it for too long.

If you’ve had new boilers and radiators fitted, sludge is most likely not the culprit. If they are still cold at the bottom and hot at the top, your system might not have been balanced properly.

How to flush radiators

If you have found the bottom of your radiator is cold because of sludge, you will need to manually flush the heater to get rid of it. First, though, you need to figure out which cold radiator is the source of your troubles.

Are all of your radiators cold at the bottom, or is it just the one? If sludge has settled inside the first heater in your system, it may be causing issues for the rest of them, as well.

Keep in mind that if you have a pressurised system, you will need a Gas Safe registered engineer to carry out the cleaning for you.

However, if you have an unpressurised, open-vent system, you can try and flush radiators to remove sludge yourself. It’s a good idea to have a helping hand there, as heaters can be heavy.

So, here is how to flush radiators that are cold at the bottom:

Sometimes, the grime will be too stubborn to remove. If this is the case, your radiators will need a chemical flush or a powerflush. This should only be done by professionals, so make sure to contact a Gas Safe registered engineer.

Once a technician flushes the radiator, they can add corrosion inhibitor to your system to prevent sludge from building up again. Just keep in mind that central heating inhibitor needs to be changed occasionally.

Installing a boiler filter will also benefit your radiators. A magnetic filter captures all those dirt and rust particles and stops them from roaming around your central heating system. Having this installed on a new boiler can prevent you from dealing with cold patches caused by sludge in the first place.

What if your radiator is cold all over?

There are several things that may be wrong here, depending on which radiators are cold.

Do you have no heating, but the hot water is running? There might be another issue, such as a stuck diverter valve. If your radiators are only cold at the top, then they might simply need a bleed to release the air.

Not sure how to deal with a faulty radiator?

If your radiator is cold at the bottom and you don’t know what to do, we have good news! You can just let a professional plumber handle it for you!

The expert plumbers at Fantastic Services can perform a powerflush of central heating systems and save you from that pesky sludge. They can clean out your system and add central heating inhibitor to it to prevent any build-up in the future.

The certified and insured technicians can deal with anything your boiler may throw at you! They come carrying all the specialist equipment they need to complete the job and will be sure to leave your property spotless afterwards. Rest assured, your radiators and boiler are in safe hands.

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Did you find this article useful? Do you have any additional questions about cold radiators? Let us know in the comments below!

Image source: shutterstock / Vasyl90, Dean Drobot