cold radiator in microbore CH

[mickcoe]

I have a microbore 8mm central heating system with a combi boiler. It serves 10 radiators in a bungalow all at the same level. Each radiator is fitted with a TRV and a lockshield. I had one cold radiator. I closed down the other 9 and tried to flush the water through but with no success. I took the radiator off and and flushed it out with a jet spray but there was very little gunge in it. Without the radiator there hot water flows down the inlet pipe but after I've fitted it the radiator goes cold. The pipes are all in the loft and there are no kinks in them. I've tried putting sludge remover in the system to no effect. After all my efforts I have now got 3 cold radiators. I have a manifold system with two drain valves at either end. I have bled them several times to get all the air out. If my pipes are blocked is there any way I can check where the blockage is. Is a powerflush worth considering. Please help.

 

[Nige F]

Has the manifold got nuts holding the microbore to it . If so you can take the pipes out one @ a time and blast some mains water down each.. up in the roof ...and maybe connect some plastic pipe to where the rad valve connects ..led to outside ( or a braided hose) Cheaper and as effective as a power flus on micro . Then sit in loft for rest of day . tapping the joists .And charge for a Powerflush - Oh you`re a householder

 

[mickcoe]

Thanks for the tip. I have a manifold with 3 lots of six connections. I assume this covers 9 radiators. There is a tee taken off at each end which I presume goes to my 10th radiator which was added later. After Christmas I'll take your advice and unscrew the offending pipe and apply some pressure down it. As its microbore how do I get a good seal when I applying mains water pressure. Also do you think a bicycle pump might work.