How To Drain A Blocked Radiator

Since the turn of the New Year I have had a central heating radiator in my dining room which has been working as and when it pleases. Not having sufficient time to tackle the job after work I decided to do it this morning. It is the coldest day of the year here today so it was important that I got a satisfactory result.

I am keen D.I.Y.er having worked in the industry for over 20 years as a Store Manager.

If you lack expertise and understanding, but still want to tackle a D.I.Y. job the best place to look for possible answers is the internet. On you tube these days you can get videos packed full of quality, step by step information on tackling those dreaded jobs. Very often the information is provided by experts so you can be assured that you are being guided in the right direction.

I suspected that my problem was possibly a silted up radiator at the lowest point in the central heating system. I had previously tried bleeding the radiator to no avail.

The time had come, then to investigate.

The first job was to get the area ready and clear any furniture in the way and to give good access to the radiator bearing in mind that water could spray everywhere if anything was to go wrong. So I made plenty of room around the working area so if water did spray it wouldn't damage the surrounding furniture.

Depending how old your heating system is and what maintenance it has previously had you must anticipate that the water you will be draining off will be pretty disgusting. Mine was no exception and was a putrid rusty brown colour. Imagine if that gets on your prized possessions - you would be none too happy to get it covered in a rusty red spray.

Having cleared the area I began the process of draining the radiator as per the instructions of the video below, so enjoy watching and learning.

Now, the radiator is drained and can be removed from the brackets attached to the wall. In order to clear any silt from inside the radiator you need to flush the radiator through with a jet of water by using your garden hose pipe.

I placed the empty radiator onto a blanket on the lawn. I then inserted my hosepipe through the bottom port on the radiator and flushed water through until all signs of the reddy brown water was now running clear. Job done or so I thought.

Replacing the radiator is obviously a reversal of the removal. Once the radiator was in place and all the unions were tight I allowed water back into the radiator by unlocking the valves. The water began filling the radiator and it started heating up for a few seconds then went cold again...damn it wasn't fixed.

Mmmm what could it be now? I know I'll try bleeding it. I bled it and let out the air and this didn't solve the problem. Time for drastic action so I removed the head of the Thermostatic Radiator valve and hey presto the radiator was a hot as anything in no time.

Turns out that the piston inside the radiator valve had seized. I always used my radiators on full heat in any case so it works perfectly for now until I can order a new valve.

What a result and the whole job was done in less than an hour and better still it cost me zilch to do. My motto is if you can do-it-yourself, why pay someone else to do it?

The piston in the radiator valve should move up and down freely so that when you adjust the temperature it actually works. If it seizes and the valve closes then you get no hot water into the radiator as the valve remains shut.