My Central Heating / Radiators Not Working / Heating Up

Read This Detailed Guide Before You Call An Engineer

My Central Heating / Radiators Not Working / Heating Up

Do you have a problem with your central heating? Are your radiators not working/heating up properly? Read this before you get an engineer in!

Do you have a problem with your radiator? Are your radiators not working?

It can be annoying if your radiator isn’t heating up or has just stopped working completely. Your home will be cold which can be frustrating at some points through the year and make your home completely unlivable at others.

Your first thought when your radiator stops working is probably going to be call out an heating engineer. But before you spend a lot of time and money on a service like this, you can consider another possibility. You can fix it yourself, and to this, you need to understand what’s gone wrong and how to complete a DIY fix.

My Radiator is Warm at the Bottom, but Cold at the Top

One of the most common problems with the radiator is finding out that it’s heating up nicely at the bottom but freezing cold at the top. What on earth is going wrong here? This is typically because you have air trapped in the system and that means that the heat can’t spread as it should, leaving the majority of the radiator cold.

To fix this, you need to get your trusty radiator bleeding key. All you need to do is unscrew it just enough that you begin to hear the air leaking out. It will sound like a hissing noise but don’t go anywhere when you do this. Keep hold of that key and get ready to turn it as soon as the water starts leaking out. Otherwise, you are going to have a nasty leak on your hands. Once you have done this, you should find that the complete radiator is now heating up as it should be.

This problem usually occurs when you have been away for a long period, and the radiators have been off. You may find that you have to bleed more than one in your home if this is the case.

Do note that if you have a combi boiler, bleeding radiators does alter the pressure and can cause the system to stop working. If this happens, you do need to repressurise the system.

My Radiator is Cold at the Bottom, but Warm at the Top

It is possible that your radiator is cold at the bottom but hot at the top. While the problem previously mentioned is quite common, this one is typically quite rare. It usually suggests that there is a build up of sludge inside the radiator.

Basically, what happens is that the sludge moves around through the systems and ends up in the radiators blocking them. It can happen in one radiator or several. The only way to fix this is to power flush your radiator (read also: Why You Should Be Power Flushing Your Central Heating). If there’s a problem in one radiator, you might be able to do this yourself, if you feel confident enough to manually remove the radiator from the wall.

When doing this, make sure that your heating has been switched off for a good few hours. This will avoid you getting hurt by boiling hot water. Before you take the radiator off the wall, lay down some old blankets sheets and ideally a waterproof covering. Water will spill out the radiator, and the sludge may also drip through.

Make sure you have a bucket ready for any leaks. After you have done this, you can remove the radiator and take it outside. You need to hose it through until all the sludge is removed. After that, you can put the radiator back in place, and it should be working again.

Why You Should Be Power Flushing Your Central Heating

All Radiators Warm Except One Cold All Over

All your radiators could be working great except for one. One is completely cold. This problem is a tad trickier to fix, but you can still resolve the issue without calling out a heating expert.

The first step is to make sure that both the valves are open on that specific radiator.

It’s quite possible that they are not and if that’s the case, you’ll need to turn them to the right position. Both valves should be turned until they are both fully anticlockwise.

You might be able to do this without taking the cap off but, for good reason, they are often quite stiff.

Remove the cap, and you’ll find a square screw. All you need is a spanner, and you will be able to turn this easily.

There are two valves. One is to control the amount of hot water entering the radiator, and the other is an isolation valve. The isolation valve should always be opened fully to ensure that your radiator does heat up.

Recommended reading: No Hot Water from Boiler: Our Ultimate Troubleshooting Guide

Thermostatic Valve is Stuck Closed

The other problem could be a thermostatic valve is stuck closed. Thermostatic valves are used to control the temperature of the radiator. Occasionally, they do get stuck, and even though they look like they are open, they are actually closed.

Repairing or replacing a valve can be quite tricky for amateurs and will often involve draining the entire central heating system before checking it’s working again.

If you want to avoid this, there is an easier option here. You can carefully unscrew the nut on the valve. It is crucial that you only unscrew one nut and that it is the right one. If you unscrew all three your room will flood with water.

The nut that you need to unscrew is the top one that is circular but has rough edges or bumps on the outer rim. You should be able to unscrew this with your fingers, but it may take a little effort to loosen it.

Once you have done this, you’ll see a small pin underneath. To let the water through it needs to be up. Try moving it. If it doesn’t move the valve is stuck shut.

If you tap it, you can loosen it a little and move it into the upright position. Water will then flow through, and you can put the screw back in place.

Thermostatic Valve

Radiators not Working – All Radiators are Cold

Usually, this isn’t a problem with the radiators, at all. It’s an issue with your boiler. If you check the boiler, you may find that it is not working. First, make sure that it is lit and ensure that the burners for gas are ignited.

If you have a combi boiler, it might be something to do with the pressure. Have a look at the pressure gauge and make sure that it is in the region it should be, as directed by the manual for your boiler. If it’s not, you should be able to turn up the pressure by adding more water, and this will get the radiators working again.

Boiler is Working but All Radiators are Cold

The other possibility is that it’s an issue with your thermostat. Don’t forget that you can turn your radiators up at the source but if the thermostat is on low, they’re not going to heat up.

Some thermostats have automatic temperature settings that need to be altered to get the radiators to a higher temperature. This is usually a problem in rented accommodation where the thermostats have been set by the landlord.

Check your thermostats and try adjusting the temperature. You should find that after a few minutes the radiators do begin to heat up.

Lower Temperatures Than Usual

Again, this can be an issue with the thermostat so make sure that you do check it again and look to see that it is set to a reasonable temperature. If it isn’t, turn it up until you notice a change in the temperature of the radiators.

Alternatively, it could be another problem with the boiler. Check the temperature of the boiler and if it is low, turn it up. If neither of these changes makes a difference, it could be a problem that might need a heating expert to have a look at it.

We hope this helps you deal with some of the most common issues with your radiators not working without the need for the services of an expert engineer.

This article is not intended to constitute professional advice and should not be relied upon. If your radiators are not heating up and there is no easy fix to that, you should give PHS Ltd a call and we will have an experienced, fully certified heating engineer out to you in no time.