Standard 15mm copper is robust. Microbore pipework is thin-walled and fragile.
Microbore central heating systems, also known as microbore piping systems, have been used in homes for several decades. These systems utilize smaller diameter pipes (typically 10-15mm) to distribute heat from a central boiler to radiators throughout the house. While microbore systems have their advantages, such as lower installation costs and reduced pipework, they also have some significant drawbacks. In this review, we will discuss common problems associated with microbore central heating systems. microbore central heating problems
Microbore central heating systems, popular in the 1970s and 80s, use small-diameter copper or plastic pipes (typically 8mm or 10mm) to connect radiators to a central manifold . While they were originally favored for being easy to install, they are prone to specific maintenance and performance issues. Common Microbore Problems Sludge Blockages (Magnetite): The most frequent issue is the buildup of "black sludge" or magnetite. Because the pipes are so narrow, even small amounts of sediment can cause a total blockage, particularly where the larger 22mm main pipes reduce down to the smaller microbore size. Kinks and Physical Damage: Soft copper microbore pipes are highly malleable and easily kinked during installation or by accidental impact (e.g., being hit by a vacuum cleaner). A single kink can severely restrict water flow, leading to cold radiators. Manifold Issues: The central manifold, which serves as the distribution hub for the radiators, is a common site for hard water limescale and sludge accumulation. Blockages often occur on the "flow" side of the manifold, preventing hot water from reaching the radiators. Difficulty Cleaning: Standard power flushing is often less effective on microbore systems because the high-velocity water may not reach all parts of the narrow pipework. Some plumbers are hesitant to power flush these systems due to the risk of bursting older seals. Fragile Valves: Radiator valves on microbore systems are small and easily damaged. Twisting a valve without properly supporting it can kink the pipe directly underneath the floorboards. YouTube +5 Performance Limitations 13 sites Microbore central heating problems. Jan 16, 2018 — Standard 15mm copper is robust
If the system is consistently problematic and radiators are cold despite cleaning, the only permanent fix is often replacement. Microbore central heating systems, popular in the 1970s
Microbore systems do not usually run continuously from the boiler to each radiator. Instead, they run a large "main" pipe (usually 22mm) to a central point, often located under the floorboards or in a cupboard. This point is the , where the large pipe splits into several small microbore lines.
Installing a magnetic filter (like a MagnaClean) on the return pipe near the boiler is arguably the best upgrade for a microbore system. It captures the black iron oxide sludge before it reaches the boiler or clogs the microbore pipes.