Brown floating bits in hot water

liviboy

Recently started to have these floaters appear in my hot water (unvented cylinder installed a year or so ago along with new expansion vessel).

When pressed against bath they cause a brown ‘smear’.

Floating bits come out of other hot taps so it’s not a faulty/degrading tap.

Got the plumber who fitted coming out to have a look but in the meantime any thoughts/ideas?

Veteransaver

Does it seem to be rust? Does it smelly irony at all?
Are the immersion heaters operating on the tank (thinking one of those may have gone kaput?)

liviboy

No immersion heater in use.

No smell at all.

ThisIsWeird

Hard water area?

If so, could it simply be 'scale', coupled with natural impurities in the water? But it doesn't fit with your description of it smearing, so no idea...

That's a sizeable quantity, but it's also floating, so will hopefully be concentrated at the top of your cylinder where it can be drawn off - assuming it doesn't keep coming back.

A mystery.

Albermarle

Presume you have not seen any issues with the cold water, and that you are getting water from the normal mains supply ?

liviboy

No issue with cold.

We’re in good old soft-water Scotland so not scale.

its been on and off for a couple of months 

FreeBear

What temperature are you keeping the tank heated to ?

If it was in the 20°C to 40°C, it could be a bacterial growth. In which case, a 55-60°C blast will kill it off.

Eldi_Dos

Second putting temperature up beyond 60 deg, leave for a few hours then flush out all your hot taps. Do it a few times.

If you have a shower fed from the tank, give the head a good clean out and sterlise.

Green_hopeful

Sometimes you can get slime in pipes but I don’t know if that comes out like that. I clean the inside of my taps about once a week with a toothbrush. I get black stuff on the kitchen tap if we don’t do it often enough. 

MattMattMattUK

My guess would be some kind of bacterial or fungal growth, but I am guessing that you do not have a microscope you could stick some of it under?

liviboy

Thanks all for the replies.

Temperature is 60.

It's not restricted to one tap/room, it happens in any hot water tap so it's definitely within the system itself.

Plumber came out - the expansion vessel was discharged (1bar instead of 3) so it was re-charged.

He is also planning to come out and exchange the flexible hose connecting the cylinder to the expansion vessel.

Don't think it's bacterial or fungal - it's a sealed pressurised system and the hot water is used in full every day (3 showers plus a nightly bath for little ones) so there shouldn't really be any opportunity for growth to occur.

Plumber has suggested he may do a drain down and re fill a few times to whip up some turbulence inside the tank to try and clear anything that might be there. He also plans to return to the manufacturers if the problem continues.