Blocked CH pipework

[yoda]

Unfortunately, I suspect I may know the answer to this question, but.....

We have a downstairs rad that refuses to warm up. All other rads in the house are fine.

The rad has been removed and flushed clean - very mucky and sludgy inside.

We refitted the rad and it fills fine from the TRV (the return, judging by the direction of the arrow) but it does not fill if we empty the rad again and open the flow valve.

At the risk of flooding the hallway, we removed the rad (again) and opened the flow valve. The valve mechanism screws itself open OK but the flow of water is barely a trickle.

The pipe feeding the flow valve gets very hot very quickly so I suspect there may be a blockage either in the valve or in the pipework close to the valve.

I really need to get the valve off to inspect it and the pipework leading to it. Is this going to require a full system drain down or is there some 'sneaky' method of localised flushing (hosepipe / compressed air etc) which might shift the obstruction ??

Or is trying to flush a blockage in CH pipework not a good idea as it may just transport the problem elsewhere in the system ?

Many thanks for any advice....

 

[ChrisR]

You could try connecting a mains hose to the "slow" valve, for a short blast. (Garden hose adapters will fit). You might be lucky - at worst you're no worse off.
If the pipe's cold you can freeze it further back, to replace the valve - saves draining.

 

[yoda]

You could try connecting a mains hose to the "slow" valve, for a short blast. (Garden hose adapters will fit). You might be lucky - at worst you're no worse off.

Cheers, Chris - That's what I was hoping. I couldn't see that it would do any damage but thought it wise to check

If the pipe's cold you can freeze it further back, to replace the valve - saves draining.

Nice thinking !!

But how do you go about freezing the water in the pipe (sorry if the question seems a bit dim )

 

[ricarbo]

With a hired pipe freezing kit or, if you're brave, buy an aerosol pipe freezing kit. When those first couple of drips start coming through the ice plug, you know you've had it!!!!

 

[bathjobby]

yoda, agree with ChrisR as I successfully used the garden hose technique on around half of my rad pipes last year and was amazed at the muck which came out. After I'd screwed the garden hose connector onto the rad pipe connector, I then used a female connector that auto closes when disconnected from the male tap connector (they have a red dot on them normally) on the end of the hose and this made it a clean process. So after turning the water on, stick you finger in the end of the female connector to let all the air out, then bang it on the rad connector for a few secs, pull off and watch the sludge run into your catcher.

 

[yoda]

Top advice guys - many thanks for your help

Will try not to get too wet tonight !!