What are microbore pipes?
Microbore pipes are thin copper tubes, usually between 6mm and 10mm diameter, that were popular for central heating systems from the 1970s onwards. They're much narrower than standard heating pipes and come in flexible coils, making them easy to bend around corners and obstacles without extra joints.
The main advantage is easier installation - you can thread them through tight spaces in older homes without major disruption. They also lose less heat because there's less surface area exposed to air, and systems need smaller boilers since they hold less water.
However, there are downsides. The narrow diameter restricts water flow, which can leave radiators lukewarm, especially with modern high-output systems. They're also prone to blockages from heating sludge and can develop leaks over time due to their thin walls.
If you're considering a heat pump, microbore pipes often need upgrading to larger diameter ones. Heat pumps need good flow rates to work efficiently, and microbore can really hold them back.
Interested in more details?
What Are Microbore Pipes?
If you've ever wondered about those thin copper pipes snaking around your home's heating system, you're likely looking at microbore pipes. These narrow tubes, typically measuring between 6mm and 10mm in diameter, are much smaller than standard central heating pipes and were quite popular in UK homes from the 1970s onwards.
Microbore pipes come in convenient coils that can be bent by hand, making them incredibly flexible for installation. This bendability means they can weave around obstacles without needing extra joints or extensive soldering work, which originally made them attractive to both professional installers and DIY enthusiasts.
Where You'll Find Microbore Systems
You'll most commonly encounter microbore heating in older UK properties, particularly homes built or renovated between the 1970s and early 1990s. They're also prevalent in flats and properties where space is at a premium, as the narrow pipes can fit through tight gaps and around awkward corners that would challenge larger pipework.
Many retrofit heating installations in older properties chose microbore for its convenience, especially when adding central heating to Victorian terraces or period properties where running standard pipes would have meant significant structural work.
The Advantages of Microbore
Microbore systems do offer some genuine benefits. The installation process is typically quicker and less disruptive since the flexible pipes can follow existing routes through walls and floors. Because they contain less water than standard systems, you can often use a smaller boiler, which can mean lower initial costs.
The reduced surface area of these narrow pipes also means less heat loss during distribution, which sounds efficient in theory. For properties with limited space for pipework, microbore can be the difference between having central heating and not having it at all.
The Downsides You Should Know About
Unfortunately, microbore systems come with significant drawbacks that have become more apparent over time. The narrow internal diameter restricts water flow, which can lead to poor radiator performance. You might notice some radiators never get properly hot, or that your heating system struggles to warm the house effectively.
Blockages are a persistent problem with microbore pipes. Sludge, debris, and limescale can easily obstruct the narrow passages, and clearing these blockages often requires professional intervention. In some cases, sections of pipe need complete replacement.
The thin copper construction makes these pipes more vulnerable to leaks, particularly as they age. Mechanical damage from DIY work or general wear can create pinhole leaks that are tricky to locate and repair.
Modern Heating and Microbore Compatibility
The rise of heat pumps has highlighted microbore's limitations. Heat pumps require good flow rates to operate efficiently, and microbore systems often can't deliver the necessary water circulation. If you're considering a heat pump installation, you'll likely need to upgrade your pipework to 15mm or larger diameter pipes.
Even modern high-efficiency boilers can struggle with microbore systems, as they're designed to work with better water flow rates than these narrow pipes can provide.
Costs and Replacement Considerations
Replacing a microbore system typically costs £2,000-5,000 for an average three-bedroom house, depending on access and complexity. Whilst this seems expensive, it's often more cost-effective than repeatedly dealing with blockages, leaks, and poor heating performance.
Regular maintenance becomes crucial if you're keeping microbore pipes. Annual system flushes and inhibitor treatments help prevent blockages, but expect to pay £300-500 annually for proper maintenance.
Common Mistakes to Avoid
Don't ignore cold spots on radiators - they often indicate blockages developing in microbore pipes. Avoid trying to increase boiler pressure to compensate for poor flow, as this can damage the thin pipes.
If you're planning any heating upgrades, assess your microbore system's condition first rather than assuming it will work with new equipment. Many homeowners discover compatibility issues only after installing new boilers or heat pumps.
Microbore represented a practical solution for its time, but modern heating demands often exceed what these systems can deliver reliably.
Liked the answer? Share it and help others!