New unvented system poor central heating performance

[Noflow]

Had new unvented system fitted about a month ago and the plumber has never managed to get good consistent performance from the radiators. Cylinder was pre plumbed by the manufacturer, new 24kw boiler, all new pipework, 7 out of the 11 radiators are the old ones from the previous system. We have at times had heat in each of the rads although never all at once. Plumber has tried balancing to get heat to problem rads with limited success and as soon as settings altered on other rads, problem rads loose all heat and become stone cold. Currently have, 2 hot rads, 6 Luke warm rads and 3 stone cold rads (literally freezing cold). The problem rads are at random points in the loop. Water returning to the cylinder is feels hot. Any ideas? Could sludge from old rads be moving round new system causing blockages and slowing flow. Even when rads are hot they do not seem to have the heating effect that one would expect.

 

[gavinda]

it sounds like the system just needs balancing correctly. the system should have been flushed by the 'plumber' already. just dont pay him until he has your system working correctly.


you havent payed him , have you?

 

[Noflow]

It's not a balancing issue. That's been done half a dozen times.

 

[gavinda]

what is the water quality like? was it flushed before the new boiler installed. did the plumber extend the systemd

as for balancing, once done correctly, altering settings on the other rads should have no advers effect on other radiators, should only make the hotter in fact.

i suggest you get him to balance it again, properly.

 

[mehran]

sounds like poor system design!, how are they pipe up? is it in 10mm or 15mm to the rads? what are the main flow and return done in?

do the rads have trv's?

 

[picasso]

turn off the hot water and make sure the zone valve for the cylinder has closed, then see if your central heating has improved.

 

[spraggo]

The problem rads are at random points in the loop. Water returning to the cylinder is feels hot. Any ideas? Could sludge from old rads be moving round new system causing blockages and slowing flow. Even when rads are hot they do not seem to have the heating effect that one would expect.

You mention, points in the loop, and you also state that the return is hot, which gives all indications that you have a one pipe system. Converting it to two pipe would seem to be the solution. What type boiler do you have?.