2 rads cold, microbore pipes

[Arturo]

My CH system is pump & header tank type, 2 1st floor rads have never worked. Boiler is on ground floor in garage, hot tank in airing cupboard on 1st floor, expansion tank in the loft. System is connected with microbore pipes.

After trying everything I have read about (balancing, bleeding, draining & refilling system, removing & flushing the cold rads), they still don't work.

Is the likely cause a block in the pipes? Does this mean carpets & floorboards up? Or can I safely use a flushing chemical? I'm nervous about making things worse, by moving the pipe blockage (if that's what it is) to a more serious place & stoppoing more rads from working.

Thanks for any advice.

 

[oilman]

You could try something like Kamco Hyperflush, though there is Fernox and Sentinel as well as others, to clean the system. This chemical lowers the surface tension, and allows the chemical into the blocked bits. Leave it in for a couple of weeks, and see if it helps. It may find some leaks, but you can fix this with leaksealer.