Dirty radiator water

[bengasman]

...I am going to change those 15mm pipes to 22mm in the next few days as I have not put the carpets in yet. After that I might try connecting a hosepipe to my system and blast out whatever is in there then try the DS40...

If there is no flow, no chemical is going to change that. A mainsflush as described in FAQ might be a better way to "blast out" a blockage.
I would try this before changing the pipes; bigger pipes give more flow, but do nothing to increase pressure.

 

[bengasman]

...I am going to change those 15mm pipes to 22mm in the next few days as I have not put the carpets in yet. After that I might try connecting a hosepipe to my system and blast out whatever is in there then try the DS40...

If there is no flow, no chemical is going to change that. A mainsflush as described in FAQ might be a better way to "blast out" a blockage.
I would try this before changing the pipes; bigger pipes give more flow, but do nothing to increase pressure.

 

[tamz]

If you are draining the system taking the rads off and flushing through with a hose will help

 

[Blob]

I cant find anything in the FAQ about 'mains flush' or about cleaning the system, only about what the chemicals do. Maybe I am looking in the wrong place. Could you please give me the link to the post or copy it into this thread.

Thanks

Blob

 

[bengasman]

It has been moved to the wiki for some reason.

//www.diynot.com/wiki/plumbing:flushing_heating_systems