why is my radiator not working

Letsgo Tnt Gas & Heating Engineers

6 Good Reasons Why Your Radiators Are Not Working

Winter is the time of the year that we all rely on our heating system keeping us warm, but when something goes wrong, and one ore more radiators are not heating up, panic sets in and we don’t know what to do.  First thing that comes to mind is an expensive call out for a  heating engineer to repair the problem.  There could be a number of reasons why one or more radiators have either stopped working, or are only partially warm.  We are here to give you some tips on how you just might be able to fix this problem yourself.  Read on!


Faulty Or Jammed Thermostatic Radiator Valve

How do I know if the thermostatic radiator valve is faulty?  First of all, don’t panic.  Check to see if the valve setting is switched on. Sometimes people turn them off in the summer months but forget to turn the knob onto in the winter.  Most valves go up to a setting of 5, this being the maximum temperature.  If the valve is turned on but the radiator doesn’t get warm then unscrew the head and take it off and you will see a metal pin on top of the valve.

Radiator Valve

Get a metal object such as a flat head screwdriver and place it on top of the pin and try to push it in and out.  If it does, chances are the pin was just jammed closed and has now freed up the valve to allow water through to heat the radiator. If it doesn’t , then your valve is most likely faulty and will need replaced by a professional heating engineer.


Air Trapped In Your Radiator

If you  put your hand on the top of the radiator and you noticed that it’s cold, this would indicate that you have trapped air in the radiator and this can easily be fixed.  When air gets trapped somewhere in the heating system, it prevents proper ciculation and will need to be removed before the radiator/heating will be able to work properly again.  The radiator will need to be bled to allow the trapped air to exit the system.  Once this has been done, the radiator should then start to get warm in seconds.

Before you start bleeding the radiator, ensure that you have a rag or a small bowl that can catch the water that comes out of the vent screw.  Once you have this, place the bleed key onto the valve and open it slowly.  You will hear a hissing sound.  This is air coming out which will be followed by water confirming that the radiator is fully topped up.  Once this happens, close the vent screw, give it a couple of minutes and you will feel the heat coming through the radiator.   Once you have done this, and, if there was a lot of air in your system, you may also need to top up your pressure in the boiler.

Trapped Air In radiator


Radiator Leak

These can be a bit more tricky to detect, if your boiler keeps losing pressure and you need to top it up, chances are you may have a leak in one ore more of your radiators.  Don’t panic!  First of all, do a visual check to see if there is any water coming from any of the joints that are connected to your radiator.  If so, and you feel comfortable with doing so, try to tighten the leaky joint with a wrench but do so with caution.

This might be all that is needed to stop the water coming out of the joint that is connected to the thermostatic valve on your radiator.  Don’t forget that you will most likely have to add pressure into your boiler as it may have dropped pressure that was caused by the leak.  If you do not feel at all comfortable trying to tighten the leaky joint, call out your local heating engineer to fix it.

Worst case scenario, if your radiator is rusty and has a leak coming from it you would probably be better off having the radiator replaced by a heating engineer as it is no longer serviceable.

Issue With Your Heating Controls

Although this problem is rare, it can happen. Don’t panic!  First of all, check to make sure that the thermostat has power.  If it has power, check to make sure that it’s actually turned on.  Ensure your boiler is turned on both at the mains and the appliance.  Although this advice might seem self evident something as simple as this could save you from an expensive call-out charge.  In the event of a power cut, your boiler can turn off but fail to come back on when the power is restored.

If you have a wireless room thermostat then you should check to see if the batteries need replaced before you do anything else.  Changing the batteries will solve the issue of your boiler controls not working.  Most wireless thermostats have low battery warning lights that flash on/of to alert you that the batteries need replaced.

Another possible issue that could cause the boiler not to fire up, is the location of your thermostat.  It might have interference which in turn could cause problems communicating with the boiler.  Try relocating it nearer to the boiler to see if this helps.  For example, installing the thermostat near a poorly insulated area in your home or too close to a heat source, such as a radiator or the boiler itself, can cause inaccurate readings which may cause it to lose communication.

If this is the case, you need to relocate the thermostat to a more neutral spot in your home to improve its accuracy.  Moving your thermostat to a different location shouldn’t be difficult if the device is wireless.  If it’s wired, you will need a technician or electrician to move the thermostat.  If you are unsure about how to fix the proble, you should contact a heating engineer.


room thermostat


Faulty Diverter Valve

If the thermostat is asking for a heating demand and responding correctly and you have the correct pressure in your boiler, yet there is still not any flow, this could indicate that there might be a problem with the diverter valve inside the boiler.

The diverter valve responds to a demand for heating and or hot water and controls the flow of warm water to either your heating or taps.  It prioritises a hot water demand over heating and allows water to run to your taps, meaning if you turn your heating on and require warm water from your tap, the valve is going to move the feed to the tap first.

If you get hot water to your taps but not to your radiators, this could be an indication that the diverter valve might be stuck.  This is not something that you should try to fix yourself.  You should contact a qualified gas safe engineer to fix the problem.

Sludge, Debris Or Blockages

If the radiator or radiators are getting warm at the top but cold at the bottom, this is an indication that the radiators have sludge and the heating water in the pipes could also also be full of sludge.  This can also cause blockages which lead to poop circulation of water going around the heating system.  This is something that needs immediate attention as the sludge could cause damage to components inside the boiler and worst case scenario even requiring the boiler to be replaced.

You should call your local heating engineer to come and assess the situation.  A heating engineer should test the water quality and if the system is sludged up, he will need to flush it with a chemical cleaner.  The engineer might also need to agitate the radiators to get as much sludge out of the radiators as possible.



Hopefully you have found this information helpful with how to fix minor issues with your radiators, thus saving you some of your hard earned money.   However, if you do not feel comfortable in trying to fix minor issues yourself, it would be recommended to contact your local heating engineer to assist you.




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