Cold Rad after Replacement!!!!

[wfoot]

Have just replaced radiator with towel rail (large one). When refilled and turned on boiler all rads are working properly except one.

It is stone cold including the tails. Have played with LSV and WHV but no joy.

The Rad is on a microbore system with an inverted loop which wasn't drained during the replacement and non of the valves were touched on any of the radiators except the one being replaced.

Any ideas

Gratefully

 

[JohnD]

Microbore so perhaps you have dislodged a bit of sediment which has clogged it

Did the old rad have black mud in the bottom?

 

[wfoot]

Some but not a huge amount.

There is another rad which is not warming properly, and is cold at the bottom, which i presumed was sludge?

 

[JohnD]

Yes, probably. It collects and forms a solid mass.

Buy yourself some chemical cleaner (and inhibitor to follow after flushing). Sentinel (Betz Dearborn) and Fernox are good brands.

It is possible (once you have put the cleaner in) that if you turn off all the rads except the blocked one, the pump might push it through.

If you get a magnet and put it against the copper pipe, it will be attracted where there is a blockage, since the black is from iron. If you can't flush it out (read FAQs for more detail) you might have to open the pipe and poke it.