New radiators, new pump but still not warm!

Chrispie

Hi all, I don't know if anyone can help here but we're stuck at what to try next. My husband fitted 6 new radiators 2 weeks ago (leaving 2 original ones in place). Decided on new ones because the old ones had been in place at least 18 years to our knowledge and when we put our heating on this year they didn't get very warm despite bleeding and balancing. Having read on DIY forums we thought our problem was due to sludge in the rads. Our new rads get warm at the tops but stay cold at the bottom. On Friday my husband fitted a new CH pump but we still have warm rads at the tops only. (The 2 original radiators that weren't replaced get hot all over). We can hear gurgling noises from the pipework as if air is in the system but very little comes out when we bleed the rads, if at all.
Has anyone experienced this before? Should we resort to a Power Flush or is it a case of expelling the air that seems trapped in the pipes? Any help will be appreciated as we're running out of money to keep replacing things!

Ruski

What temperature are the pipes feeding the rads - hot one side cold the other? Are existing pipes in a solid floor or dropped from ceiling?

Too many questions to ask - but we need to know more diagnose

Chrispie

Yes, one pipe is hot and the other is cold. Existing pipes are under a solid floor (concrete I think)

greyteam1959

Have you tried turning the speed of the pump up ???

Chrispie

Yes and this seems to make the gurgling noise in the pipes worse and eventually the boiler warning light starts flashing

southcoastrgi

sounds like the system needs balancing

espresso

When was any cleanser/de-scaler/inhibitor last added to the system?

Chrispie

Recently, about the end of October

espresso

Chrispie wrote: »

Recently, about the end of October

Was it added regularly previous to October this year?

unclebulgaria

Just an idea but, can you find a magnet and go to the pipes above and below the new central heating pump and tell us if they show signs of being magnetic?

Chrispie

No, the cleanser was added about 2 years ago prior to this October.

I will try the magnet on the pipes but I'm now at work so will do this tonight.

Thanks for your help