UKH

Hi

I have an old electrical combination hot water tank in my flat (small cold water header tank is above, and integrated into the hot water tank construction), and recently had to replace the header inlet float valve.

When I lifted the lid of the header, I discovered the remains of a large (about dinner plate diameter) heavily corroded, turquoise-copper-sulphate-crystal-encased and broken-up tube-like ring lying in the bottom of the tank.  There is also the remains of a stub of similar corroded tube poking up from the bottom of the header tank that presumably the broken bits were attached to (maybe this comes from down in the hot part of the tank?).  So the whole ring thing must have looked a bit like a large circular heating element.  But this is the cold water header tank!

Does anybody know what the corroded broken tube ring thing could have been?  And is it important?

Can't find anything like that online.

Cheers.

Sounds like a sacrificial anode although I thought it was unusual to fit them to cold water tanks.

Interesting if that is the case.  It does not look like it is replaceable.  And it's a -- or was a -- fixed ring rather than a rod...

I removed the loose old fragments from the tank and just left the fixed stub: which I imagine should have no affect on further tank corrosion, if that was its job, since those loose bits were no longer electrically connected to the tank casing.  But I still can't see anything about sacrificial anodes online that look like that.

I think you might be describing a Fortic tank with a sacrificial anode. Does it look like this, on Money Saving Expert of all places: https://forums.moneysavingexpert.com/discussion/915673/fortic-hot-water-cyl...

Hi.  Thanks.  Yes - ish.  The remaining stub is off-centre, but roughly the same as those forum pics, and the turquoise coral reef deposits in the bottom are the same.

So you guys are right.  And now I also know the name Fortic which pulls up a lot more relevant google hits than combination tank.

I have some remains of the crud covered tube in a bucket, and just started pulling it apart with force.  It did break up to reveal not an electrical element-like tube as I wondered, but a thin maybe 5mm dia "expensive metal" looking wire.  Prob magnesium or something.  All that's left of the anode.

So thanks guys. 

And following those forum posts it seems the anode does most of the work in the first few months of service before the tank builds its own partially protective layer.  So sounds like my tanks no worse off without it now.  No choice anyway

Thanks again both

Bruce

Great, glad to help.  Bit of esoteric knowledge from reading Without Remorse back in the late 1990s.  Second thing I've learnt from that book to prove useful.

Boat marine anodes are zinc alloy, freshwater are magnesium alloy I believe.