Copper pipework is generally robust, and a power flush circulates water at low pressure. For most homes, old pipes are not a problem. But some older systems do need extra care — and occasionally a different approach.
Copper pipes
Most heating pipework in UK homes is copper, which doesn’t corrode in the same way steel radiators do. Pipework in reasonable condition is very unlikely to be damaged by a power flush. The weak points tend to be joints, old compression fittings and valves rather than the pipe itself.
Microbore pipework
Many systems installed from the late 1960s to the 1980s use microbore — 8mm or 10mm pipe to each radiator. The narrow bore means dislodged sludge can form a blockage. Power flushing microbore is possible, but it needs:
- Careful control of how much debris is moved at once
- Flushing each radiator individually with regular flow reversal
- Checking each radiator heats properly afterwards
Steel and iron pipework
Some older properties still have sections of steel or iron pipe, especially in larger gravity-fed systems. These can be badly corroded internally. We assess them carefully and may recommend replacing sections rather than flushing.
Gravity and one-pipe systems
Older gravity-circulation and one-pipe systems work on different principles from modern pumped two-pipe systems. They can often be cleaned, but the method must suit the system. Occasionally the best advice is to upgrade the system rather than flush it.
Our approach: we check the system first, explain any risks plainly, and recommend the method that suits your pipework — a power flush, a gentler chemical clean, or replacing problem sections. You decide.
Hidden pipework and pipes under floors
In many London homes, heating pipes run under suspended timber floors or are buried in solid floors and walls. A leak on a hidden joint is harder to spot, so we pay particular attention to any signs of past leaks — staining on ceilings, damp patches, or a system that has needed regular topping up. On sealed systems, we also watch the pressure gauge after the flush; a steady pressure means the pipework is holding.
Plastic pipework
Newer systems and extensions often use plastic (PEX or polybutylene) pipe. Plastic pipe doesn’t corrode, but some types let small amounts of oxygen through the pipe wall unless they have an oxygen barrier. That extra oxygen can speed up corrosion of the steel radiators on the system. Power flushing is suitable for plastic pipework in good condition — the connection fittings are what we check.
Questions to ask before a flush on an older system
- Will you check the system and tell me about any risks before starting?
- How will you adapt the method for microbore or older pipework?
- What will you do if a leak appears during the flush?
- Will you flush each radiator individually?
A good engineer will be happy to answer all of them.
Related: can power flushing damage radiators?, power flush vs chemical flush, and our power flushing service.