Blocked pipe

[blockedpipe]

I have a couple of big radiators which stopped getting warm a while ago. They used to be ok, are fairly new, and don't show signs of sludge (i.e. clean water came out, no bits, when I first tried to fix this a year or so ago). The two radiators are the last two in parallel across the flow and return pipes, and neither get hot:

>---!----!
<---!----!

So I suspect the pipework in front of the first radiator I've had a look at it, and the return pipe seems to be in a u-bend shape around a joist, and I suspect it may acted as a trap for any bits or sludge. A bit of casting coming off a cheap towel radiator for example, or just ancient grot. Or an airbubble? But surely the pump would push that through ?

One positive here is that there are isolation values on the flow and return, with compression joints. So my thought was to attach the garden hose to these and 'blast' out any stuff. Don't want to force the same through the boiler as the pressure relief valve would open.

Thoughts - (a) is this likely to work/worth a go? and (b) how do I attach the garden hose to the end of the pipe (after unscrewing it from the isolating valve) ?

 

[twgas]

A) possibly/yes

B)use a short piece of copper tube (15mm) cunnected with a spare/new nut and olive.

 

[blockedpipe]

Thanks for your reply Mick.

I plan to close the isolation valve and detach the 'problem' side whilst leaving the rest of the system as-is. So in that case I will also need a coupler to connect the two pipes. Slightly nervous as I haven't used compression joints before, but the youtube videos I have looked at seem easy to follow.