Microbore central heating issues - cold and uneven radiators

[daveytea]

Please help!

I Recently moved into an old Victorian house. New boiler was fitted just before we moved in, but the central heating radiators and pipes were installed about 25 years ago.

There are about 16 radiators spread across 3 floors

The radiators all have 10mm grey plastic microbore feeds to them. I can only access one of the floors and have found 15mm copper going to a manifold with 8 hot and 8 cold feeds.

The issue is, On the ground floor for example, only 2 of the radiators get really hot. 3 get warm and the other 3 don't get warm at all. It's a similar picture upstairs.

Have tried bleeding, checking the valve springs, checking the cold valve is open and balancing by turning down the hot ones.

One plumber says the 10mm pipe needs replacing with 15mm copper throughout but this is a big expensive job.

Before I do this.. is there anything else to try? Perhaps:

Removing the cold radiators and cleaning them out?
Replacing the valves?
Power flush? (Apparently pointless with microbore pipe)

Many thanks

David

 

[Andy165]

Main circuit 22mm copper pipework and 15mm pipework to radiators. Bite the bullet, upgrade.

 

[omph]

You're not going to get decent flow from that kind of pipework. As Andy stated, 22mm main run and 15mm runs to each rad.

 

[daveytea]

Thanks. However I want to exhaust all possible other options because doing an expensive pipe re-fit.

I tried individually cleaning some of the rads today. Closing them off and draining and flushing each rad. Loads of black gunk came out. One of them had good flow coming through the hot feed, the others were a trickle.

I might continue to do this just as a quick way to get a load of gunk out of the system.

Question. If I quickly disconnect each of these feeds and allow the gunk to come out before reconnecting, would this work? I'll have to be pretty quick and have something to catch the water.

 

[omph]

DIsconnect each rad, take outside flush with water till clean and remount. Make sure you flush from all holes (bottom and top) to get a good clean. Once all rads are clean, get the plumber to do a powerflush and see how that goes. You might be able to get away with it if your system it gunked up.