White stuff in heating water?

[Ric2013]

Hi. No work on at present due to being abroad, so I'm writing a question I have had in my head for years.

I have a few samples of water from heating systems back in my storeroom. I like to do a nail in jar test when I've worked on a system, both as a matter of interest for myself and because I suffer from Plumber's Paranoia and worry about inhibitor concentrations.

Something I have noticed is that most samples (all of the systems I have samples from are elderly open-vented systems) appear to have a small amount of whitish yellow cloudishness that tends to settle to the bottom.

Even a sample taken from a system a week after a powerflush and treatment with (definitely sufficent quantities of) inhibitor had some whiteishness to it. This isn't the sparkling clear you'd like to see. In fact, the sample only just passed a turbidity tube test due to the presence of this stuff.

Any ideas? Hard water, algae? It isn't magnetite. Ta.

 

[centralheatking]

Black is magnetite in a sealed system or open vented system that is watertight. Brown is ferric sludge as well but in a system that is leaking and being topped usually open vented. White scales is usually temporary/permanent hardness. Other colours can be left over from various heating water treatments.
Also look out for debris from the F&E tank or cold water storage tank which enters from mains water normally or cleaning or general debris because the lid does not fit. It can also be dust from different sorts of insulation inbetween the roof rafters. Centralheatking

 

[Ric2013]

So if the system is clean but filled with hard water, is it normal to find hardness deposits in the system water? Talking about the system I powerflushed myself, the system was powerflushed with DS40 with a hired Kamco (and my own Magnacleanse kit), having been pre-treated with X400 a few weeks prior and then drained and refilled on the day, and draining would have (to some extent) cleaned the cold feed and vent pipes. I was as thorough as I could be, and took around 10 hours. And, yes, I did clean the F&E out.

There was some underfloor heating in the system which I could only flush in one direction, and, with hindsight, I might have connected directly to the UFH manifold to flush the UFH instead of relying on replacing the circulator with the powerflush machine and doing the whole system from there. Perhaps this meant the job was not as thorough as it could have been. That said, the task was certainly not rushed.

Perhaps there was more scale than the DS40 could cope with, or some scale was loosened but not fully removed? I must say I removed a Magnatech from a system that had apparently been powerflushed the previous year by others and the magnet was full to capacity - perhaps due to a similar phenomenon?