central heating microbore not fitted with manifold

[BCyork]

Radiators used to work when I moved in, though never great. Over last few years, some stopped completely, some only get slightly warm. Had numerous people look at it. Most saw the microbore and ran for the hills.

Latest attempt: engineers have tried to flush system (radiators taking off and flushed out), boiler replaced (new combi bolier installed), thermal storage tank removed (cistern part was full of crud). Now even fewer radiators working.

Engineers took up floorboards on first floor to try to locate manifold(s), expecting they may be blocked. Have found that no manifolds are used! System involves teeing off from 22mm plastic feed pipe to each radiator using what looks like 12-15mm plastic pipe, with copper microbore (maybe 10mm) visible out of the walls or floors. Engineers say this is completely wrong way to fit a microbore system. They say water flow is likely to favour following the 22mm pipe and not head to the radiator, due to pressure differentials.

Am told powerflush will be no use, and only option is looking like re-piping at high cost. Any advice out there?

 

[Ajax13]

If the flow and return are both Into the same pipe then your "engineers" are correct. If there is a flow and a return they are talking rubbish

If there are flow and return then The installation sounds fine to me. It certainly sound the same as my own. The flow should run into the rads and then be piped out into the return.

The usual issues I have seen are to do with the pump not being man enough, cavitating or jamming and the the rads must be balanced. Typically they should be set up so the the return temperature is about ten degrees cooler than the flow..