Today we’re going to have a look at the problems you might have if you’ve only got one radiator that’s not working. So let’s say you’ve got a house full of ten rads and you’ve got one radiator in one of those rooms that just won’t get hot.
Usually you’ll find that it’s actually a really really simple solution and one that you can do yourself, without actually having to call a plumber out. So let’s see how we can do that now.
There are two ends to a radiator where the heating will come in and go out. The lockshield end is generally on the return side back to the boiler, so the first thing to do if the radiator isn’t getting hot is to get yourself an adjustable spanner, or a pair of grips, and open the lockshield valve one full turn.
Now go to the other end of the radiator and, if there’s a thermostatic radiator valve (TRV) present (which there is on most radiators in the UK), make sure it’s fully turned open.
If you’ve opened the lockshield at one end and the radiator TRV at the other end and the radiator still doesn’t get hot, what you can then do is remove the radiator TRV head. Once you’ve removed the head, that will expose the TRV pin, that the radiator valve acts on.
Now often these can get stuck down in the shut position. To solve this issue, do not use anything to hit the pin with, but instead, grab a set of grips and wiggle the pin up and down in order to free it off. Once you’ve got that working properly, you should see the pin goes up and down on its own.
If you feel like it once you’ve freed the pin, you can spray some lubricant around the pin shaft to try and prevent it from getting stuck again.
Those are the first two points you should try and cover when you’ve got one radiator that isn’t working. If you’ve done all that - you’ve opened up your lockshield, turned on the TRV and freed up the pin and you’re still not getting any heat or flow through the radiator, then there’s one more thing you can probably do as a homeowner, although it is still quite advanced.
The first thing to do is shut the thermostatic radiator valve and shut the lockshield. Then get a small towel, put it under the air bleed valve and open up the bleed with a radiator key. That will dissipate any pressure that’s in the radiator because no water can now get into the radiator as both of the valves are shut.
The next thing to do once the pressure has been fully dissipated is to remove the whole airbleed assembly itself and put in a connection that will allow you to attach a normal garden hose. (½ inch male to 15mm compression with a small stub of 15mm copper is fine)
Then turn the heating system off, take the end of the garden hose outside and then open up the thermostatic radiator valve. What will happen is a large body of water will come out through the top of the radiator, go down your hose and out into the garden.
The reason to do this is potentially the remaining problem about that radiator is there could be an airlock. Flushing out the flow side through the thermostatic radiator valve will push any trapped air out.
Remember, once you’ve pushed any air out, if you’ve got a pressurised system, top up the pressure on the filling loop. Or if you’ve got a non-pressurised system, you shouldn’t have to worry as it will fill up automatically.
Once you remove any slugs of air, you will then need to shut the thermostatic radiator valve and do the same with the lockshield. Also remove your hose and reinstate the radiator with it’s airbleed, so it’s back to normal. Turn the radiator back on and with any luck, you should get some heat flowing into the radiator.
You can view a video of this radiator process on our YouTube Channel.
Alternatively, if this has not solved your problem, you are advised to watch out How To Balance Your Heating System video.
The radiator featured in the main image is a Victorian Cast Iron Radiator 760mm High.
Article by Benjamin Clarke