| Scenario | Recommendation | | :--- | :--- | | | Try a chemical cleaner (e.g., Sentinel X400) for 4 weeks, then drain. If that fails, replace that single pipe run. | | Multiple cold radiators | Do not pay for a powerflush (£500–£800). It rarely works on microbore. Replace the manifold and pipe runs with 15mm plastic or copper. | | Plastic microbore | Replace immediately. It is a ticking time bomb. | | System works fine | Add a magnetic filter (e.g., MagnaClean) and use inhibitor annually. Never let the boiler pressure drop to zero. |
Microbore central heating systems, also known as small-bore or restricted-bore systems, have become a popular choice for homeowners looking to save on installation costs. However, while they may seem like a cost-effective solution upfront, these systems can lead to a multitude of problems down the line. In this post, we'll explore the common issues associated with microbore central heating and what you can do to avoid them.
Microbore central heating systems use small-diameter copper piping, typically 8mm or 10mm, rather than the standard 15mm or 22mm pipes found in traditional installations. Popularized in the 1970s and 80s for their ease of installation and lower material costs, these systems are now notorious for specific technical failures. If your home relies on these narrow tubes, understanding the inherent problems is essential for long-term maintenance and efficiency. Chronic Blockages and Sludge Build-up
While microbore systems can function adequately if they are treated with high-quality corrosion inhibitors and filtered regularly, they are undeniably a legacy technology. If you are experiencing repeated cold spots, noisy pumps, or are planning a boiler upgrade, the most cost-effective long-term solution is often a full system "re-pipe" to standard 15mm copper or plastic piping. This ensures your heating system is efficient, reliable, and compatible with the green heating technologies of the future.
Balancing a heating system (adjusting the lockshield valves so that all radiators heat up at the same time) is much harder with microbore.
