The Hydraulic Heart Attack: Understanding and Resolving Blockages in Microbore Central Heating Systems
Diagnosing a microbore blockage requires eliminating other variables. The first step is the magnet test : sliding a strong neodymium magnet along the microbore pipe. A sudden “stick” indicates a high concentration of magnetite. The second is thermal imaging , which reveals a sharp temperature gradient at the precise point of occlusion. Unlike a standard system where blockages are typically in radiators, microbore blockages are perversely located in the 6mm branches between the manifold (a central distribution hub) and the radiator valves. microbore central heating blockage
The ultimate failure of microbore systems is that they were designed without adequate filtration. A modern standard system mandates a magnetic filter (e.g., MagnaClean or Fernox TF1) to continuously remove magnetite. Retrofitting a magnetic filter on the return pipe to the boiler can dramatically extend the life of a microbore system, but it cannot reverse existing hard blockages. Furthermore, the use of corrosion inhibitor (e.g., Sentinel X100) at installation is non-negotiable; an uninhibited microbore system will typically fail within 5–7 years, whereas a treated system may survive 15–20 years. The second is thermal imaging , which reveals