This can mean our homes aren’t being heated efficiently, wasting money and energy. A common problem that can occur when heating systems have been off for a long period of time is that radiators can be cold at the bottom, meaning they are not heating your home properly and making your bills higher than they need to be. “How to bleed a radiator” is currently the most searched DIY question of 2021.
The experts at Ideal Heating have shared their FAQs around radiator issues along with a step by step guide on how to fix it yourself to avoid pricey call out fees.
Why is my radiator cold at the bottom?
If your radiators are cold at the bottom but hot at the top, this can mean that the flow of hot water is being restricted or redirected so it’s not reaching the whole of the radiator. Often with a cold-bottomed radiator, it’s still hot around the water entry and exit points at the bottom, so the restriction is usually in the middle and at the bottom.
How do I prevent my radiator from getting cold at the bottom?
Radiators being colder at the bottom can be caused by sludge build-up.
Ideal Heating strongly recommends trying to prevent sludge build-up. The easiest way to do this is to put an inhibitor into the system. It slows down the chemical reactions that cause the iron oxides to form, so you’ll get much more life out of the system.
Just one radiator is cold - How do I fix it?
If just one radiator is cold at the bottom, it’s likely to be an issue with that individual radiator rather than a problem with your overall heating system.
In the majority of cases, the single radiator causing the issue may just need a good clean! There are three ways of solving this problem: chemical, physical cleaning and a power flush. Find out how to clean the radiator yourself with the step-by-step guide below.
How can I clean my radiator?
Step One: Isolate your radiator
If you have a thermostatic radiator valve (TRV) turn this down to zero. At the other end, there will be another valve called a lockshield valve, which is probably covered with a plastic cap. Close the valve with a spanner, but note the angle that you have to turn it – it’s probably somewhere between a quarter and half a turn. That’s how much you’ll want to open it later. If you don’t have a TRV, you’ll need to turn off both valves with a spanner.
Wait for at least half an hour to ensure the water in your radiator is cold.
Step Two: Prepare for leaking water
You’re going to be emptying your whole radiator - so expect a lot of water! Have a couple of containers on hand to make sure you can capture all of it with no spillage or overflow.
It’s also sensible to put an old towel or rags down underneath the connector nuts, with your container placed on top to make sure that any leaks can be easily cleaned away.
Next, with a spanner, turn the radiator nuts slightly. A small amount of water might drip out, but don’t expect water to start pouring out just yet.
Step Three: Open the bleed valve
Using a bleed key, open up the bleed valve at the top of the radiator. Air will now be let into the radiator, and water will start pouring out near the loosened nuts.
Step Four: Remove and clean your radiator
Once the water has stopped flowing, disconnect the valves and lift the radiator off its brackets. Make sure not to fully undo the valves, as this can empty the content of your heating system. Take the radiator outside, attach a water hose to one end and blast water through it for a few minutes until it flows clean.
Step Five: replace your radiator
Re-hang the radiator on the brackets, re-attach the pipes at the nuts and turn both valves back to their original positions. Water will start refilling the radiator, so get ready with your bleed key and close the bleed valve as soon as water begins to escape from it.
Step Six: Test your system
Test your radiator by turning your heating back on. Wait for around twenty minutes for the water to heat up, and test it by placing your hand on the bottom of the radiator and swiping up - your radiator should be emitting heat evenly now.
Once you take a radiator off a sealed system, the system will nearly always need repressurising. If you have a pressurised system, more water will need to be added to the loop to bring it back to pressure.
