If your radiator is hot at the top but cold at the bottom, it is not functioning properly and could lead to more complicated issues. This is a common problem preventing radiators from keeping the house suitably warm.
A radiator which has cold patches while the heating is on may have sludge present within it. Sludge tends to accumulate inside the radiator over time, with the build-up eventually blocking the flow channels and preventing water from moving around effectively.
Experts at Boiler Central have provided a detailed step-by-step guide to clean up your radiator and get rid of this cold spot at the bottom. A spokesperson for Boiler Central said: “Unfortunately radiator sludge is a very common occurrence and this is because of the reaction caused when water interacts with metal.
“When this happens the best thing you can do is clean the radiator completely, which can sound like a daunting task but it is something you can do without a professional.” Here is how you can go about fixing those pesky cold patches.
Isolate the radiator
If the affected radiator has a thermostatic valve, turn this down to 0. On the other side of the radiator is a valve known as the lockshield valve - which will be covered with a plastic hood.
Using a spanner, close the lockshield valve – this could be either a quarter or half a turn but take note of this, as it will be how much it needs turning to open it back up again. Wait at least an hour for the water in the radiator to fully cool.
Set up for leaking water
Have some buckets or containers close by to ensure you catch all the water that escapes from the radiator without overflow or spillage. Place an old rag under each valve to ensure any unexpected leaks do not ruin the flooring.
Open the bleeding valve
Open the bleed valve right at the top of the affected radiator using a bleed key or a screwdriver. Water will then begin pouring out from the loosened nuts.
Remove and clean the radiator
When the water stops being released from the radiator, disconnect the valves and take the radiator off its bracket. Do not completely undo the valves as this could cause the contents of your heating system to empty.
Take the radiator outside to clean and attach a hose to one end of the radiator, blasting water through for a couple of minutes until the water begins to flow clean. Connecting the hose to several different openings should ensure the radiator is fully clean.
Test out the system
Once cleaned, you can place the radiator back on its bracket. Ensure the pipes are attached to the nuts while turning the valves at either end to their original positions.
Water will begin refilling the radiator, so you must have the bleed key ready and waiting. When water starts to escape from it, you should close the bleed valve.
The heating can then be turned on and tested. After waiting for around half an hour, there should no longer be cold patches present on the radiator.
Re-pressurise
Once a radiator is removed from a sealed heating system, it must be re-pressurised. If the heating system is pressurised, add more water to the loop to level out the pressure.
The Boiler Central spokesperson added: “We’re hoping that our cleaning tips will provide some help in running a more efficient household, especially during these tough economic times. Saying this, if you’re still unsure it is always best to call a professional plumber before a heating problem gets too bad.”
