Blocked Microbore Pipes Jun 2026

The "long piece" you mentioned likely refers to a specific run of pipe (perhaps under a floor or in a wall) that is inaccessible or particularly lengthy, making the job harder.

Microbore pipes are narrow copper tubes (typically ) used in central heating systems to connect radiators to a central manifold. Due to their small diameter, they are significantly more prone to blockages from magnetite (sludge) and limescale than standard 15mm or 22mm pipes. 🔍 Identifying the Issue blocked microbore pipes

Metal filings or flux left behind during installation can snag magnetite, accelerating the buildup. The "long piece" you mentioned likely refers to

Note: Be careful with mains pressure; 8mm pipe can burst if it is old or corroded, though usually, the fitting will blow off before the pipe bursts if not clamped. 🔍 Identifying the Issue Metal filings or flux

: Open the radiator bleed valve. If air or water flows out, the pipe is likely clear but airlocked. If there is no draw at all , the pipe is blocked.

Do you know if your system has a (usually in an airing cupboard)? Have you tried bleeding the radiator yet? Unblocking Microbore Pipes - PowDer Flush

Blockages frequently occur where wider 22mm pipes reduce down to the smaller microbore size.