Is a radiator in a single room not heating up partially or at all? Here we walk through the most common causes and fixes.
Finding that all of your radiators are working but one?
In this guide, we’ll explain why a single radiator might fail to work and what can be done to fix it.
We’ll also touch on the costs of having this fixed by a professional Gas Safe engineer.
Let’s begin...
Radiator Not Working in One Room - Key Points:
A radiator not working at all i.e. remaining cold even when the heating is on is a sign that the radiator's thermostatic valve is stuck or broken.
If the radiator is only getting partially warm when the heating is on, it may be a sign of trapped air and you may need to bleed your radiators.
If your radiators are heating up at different speeds, then you will need to balance them too.
Why Would a Single Radiator Stop Working?
If you find that most of your radiators are heating up as normal but one of them is cold or at least not uniformly heating up, there are two primary reasons why this may happen.
Specifically, it may be the result of a stuck valve inside the radiator or air being trapped in the system.
Let’s explore each of these reasons separately.
Thermostatic Radiator Valve is Stuck
A thermostatic radiator valve or TRV serves the purpose of controlling the flow of hot water to a radiator.
While these are generally reliable devices, TRVs can occasionally seize and become stuck.
Should this occur, a TRV will be incapable of letting hot water in when the heating is turned on.
Old radiators are particularly vulnerable to this outcome if a TRV seizes and becomes stuck.
In this case, your radiator will likely fail to heat up at all.
We’ll discuss how this issue (and that of trapped air) can be solved in the next section.
Air Trapped in System
If air has become trapped inside your radiator can rise and form large trapped air pockets.
The result; water will be displaced and the radiator will not be able to heat up as intended.
In this scenario, you should notice that your radiator stays warm at the top but is cold toward the bottom.
This is in contrast to a stuck TRV which should prevent your radiator from becoming warm at all.
This is one way to get a sense of which of these two explanations is likely the culprit, although attempting a solution is the only way to be sure.
How to Fix a Radiator Not Working in One Room
Note: For either of these fixes, it’s important to follow the manufacturer’s instructions. However, our guides will provide you with a clear overview of what is involved.
If you are sure that it is just the one radiator which is not working, there are two DIY approaches worth considering.
It is worth checking whether a TRV is stuck before bleeding your radiators to remove trapped air.
Of course, you should only undertake this work if you have the right skills and are sure of exactly what is involved.
If in doubt, hire a qualified heating engineer.
Fixing a Stuck TRV
Firstly, you’ll want to check whether the TRV is stuck.
By following the manufacturer’s instructions, you will need to attempt approximately the following steps:
Ensure that your heating is off and that your heating is not scheduled to come on while you’re working on it. The radiator should be cool before you start work.
If the TRV is stuck, it will likely already be cool, to begin with.
Remove the TRV’s rotatable head - this will unveil the raised pin underneath.
Carefully attempt to depress the pin using a finger.
Upon releasing pressure on the pin, if it is not stuck, it will rise back up.
If this is the case, then you can move on to bleeding radiators as it suggests the TRV is not stuck.
However, if the pin doesn’t move with ease or is already depressed, then there’s a very good chance that a stuck TRV is a sole explanation for a single radiator failing to work.
With that said, it’s important to be aware that this is not certain.
While unlikely, it is entirely possible that a TRV is stuck and there is trapped air in the system.
If the pin is stuck, you can use grease and pliers to carefully move it in and out with ease. Of course, this may not work.
It’s important not to use too much force as this risks damaging the pin.
Therefore, if you cannot move the pin easily using grease and pliers, hire a qualified heating engineer.
Do not take any unnecessary risks that will cause further problems.
Bleeding Radiators
If it turns out that the TRV is not stuck, then there is a good chance that air is trapped inside your radiator.
As mentioned, this will probably result in your radiator being warm toward the bottom and cold at the top.
After all, air tends to accumulate at higher points inside a radiator when there is trapped air.
In order to remove trapped air from a radiator, you must bleed it.
You can read our complete guide on bleeding your radiators here.
Again, only undertake this work if you have the right skills or knowledge and ultimately you should follow the manufacturer’s instructions.
With that said, here are the general steps required to bleed a radiator:
Preparations - To start with, you must prepare the area
Since bleeding a radiator can be very messy, you’ll want to lay down a few old towels or even a rag just below the radiator you intend to bleed.
Also, make sure you have a bucket ready to capture any water that comes spilling out later in the process.
Moreover, you may want to put on some old clothes that you don’t mind getting messy.
Letting the Radiator Cool Down
Before actually getting to work you must also ensure that the radiator is cool.
This means turning off your heating and waiting until the radiator has cooled down completely.
After all, when a radiator has trapped air, the bottom will likely still be warm if the heating is on.
P.S., be sure to check that your heating is not scheduled to come on while you’ll be working on the radiator!
Opening up the TRV
Fully open the thermostatic radiator valve of the radiator in question.
This means simply turning it to the highest number on the dial.
Alternatively, if your radiator lacks a TRV, just be sure that the lockshield valve is open.
Opening the Bleed Vent
Next, it’s time to find the bleed vent.
This will likely be found toward the top right of your radiator, but again, your manufacturer’s instructions will provide clarity.
After locating it, insert the bleed key and turn anti-clockwise. As you do so, you should notice the sound of air escaping.
That is before water will begin to leak from the valve. With your bucket ready, allow a small quantity of water to come out.
You may also want to have some tissue or cloth just below the bleed valve when you first open it up as a way of reducing the risk of dirty water splattering on the floor or walls.
Close the Vent and TRV/Lockshield Valve
Now it’s time to close the bleed valve. Be sure not to over tighten it, though, as this can lead to damage.
Once you’ve done that, be sure to turn any valves back to their original position(s), whether if be the TRV or lockshield.
Look at Your Boiler’s Pressure
Lastly, once you’ve completed bleeding your radiator, check the pressure of your boiler via the pressure gauge.
In most cases, a boiler’s pressure gauge should reveal a pressure of between 1 and 2 bars.
However, for your boiler in particular, check whatever the optimal range is according to your manufacturer’s instructions.
Having bled your radiator, it’s entirely possible that the pressure will have dropped below 1 bar.
Either way, if your boiler’s pressure is too low, you’ll need to top it up (i.e., repressurise it).
Again, you should follow the manufacturer’s instructions for this but you may also want to have a look at our boiler losing pressure guide.
Do you need to balance your radiators?
If you have bled your radiators and had your system flushed, but you are still experiencing a cold spot in a particular radiator, it may mean that the hot water from your boiler is not being evenly distributed to all your radiators.
This may mean that your radiators may need to be balanced i.e. make the water flow evenly from your boiler to each of the radiators in your home.
Here's our complete guide on balancing radiators.
For instance, if the radiator furthest away from your boiler is the one that is failing to heat up, it’s a reliable sign that your radiators need balancing.
Cost of Hiring a Professional to Fix a Radiator Not Working in One Room
Whether you need to hire a professional or you’ve even tried it DIY and had no luck, it will cost approximately £30 to £60 per hour (in labour costs) to hire a heating engineer.
The cost of labour can differ depending on where you live.
Prices tend to be under the UK average in regions such as the north of England and Scotland, while they are usually above average in the southeast of England.
The overall cost of having your radiator fixed may also include supply costs (e.g., if you were to have a TRV replaced this would require labour and supply costs alike).
Here are the average costs of hiring a heating engineer to fix your radiator:
Fixing a stuck TRV - £30 to £60
Replacing a TRV - £40 to £120
Having one radiator bled - £30 to £60
Having all radiators bled in your home - £60 to £180
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