Magnetite in CH System - How long to form

[TheScullster]

Hi all

Having flushed my old CH system repeatedly with fresh water and all-manner-of cleaners, I was disappointed to find that my MagnaClean filter had "picked up" significant amounts of crud after 1 year of operation post-upgrade. (I had at some point either replaced or removed and manually flushed all rads as well). The material collected by the filter was approx half sludge and half gritty magnetite.

As I had the main pipe route upstairs changed from 15 to 22mm, the mechanical disruption as well as the improved flow could well have released some more stubborn crud I expect.

So the question is, will the larg(ish) magnetite crystals form in the space of a year, or is this more likely to be stuff that has been dislodged from the old pipe work.

If this material is still being created, then I will have to look for a possible cause. Haven't seen pump over issues and the layout around the pump and vent appears correct.

TIA

Phil

[Ed Sirett]

The bits are more likely a mixture of the oxide (probably magnetite) and limescale. It seems that no matter how well you clean the old system out there are always some bits that remain. Presumably the old system had significant issues but these have been addressed with the new system. So if no pumping over is happening and there is no air/gas collecting in any radiators then there is no real cause for concern. Of course I haven't seen just how much crud you've seen and called 'significant'. In part a combi boiler may be more sensitive to the bits if they get stuck in the plates of the DHW exchanger, but that is easy removed on many models and easily descaled.