Mould / 'cardboard' like substance in header tank

UpgradeME · 12 Mar 2012

Hi,

Just had a look in my header tank and found the following:

Untitled

UpgradeME
12 Mar 2012
1

The white bits looked like 'mould' and the brown was what I could only describe as like soggy cardboard (in texture) and about 1-2mm thick covering almost 99% of the water surface. Does anyone know what the 'cardboard' like stuff is and/or the cause?

I haven't really touched the system for around a year, at that time I ran some Fernox F3 for a few days, removed the downstairs rad's and flushed, cleaned the header and refilled adding some Fernox F1 (I added the F1 in the header as I was re-filling the system); the system has a Spirotrap fitted which I checked last week, following roughly a years usage there was some magnetite collected (not a great amount) and the water was pretty clear.

The water was clear(ish) under the brown, however, as I've disturbed it since scooping off the top layer of brown/mould I'm waiting for it to settle again to check what really lies beneath before emptying / cleaning the header (currently there's lots of 'bits' in it swishing around).

crockett · 12 Mar 2012

Hi there, have a read of this

http://www.fernox.com/files/Fernox/Content/PDF/English/HTSBacterialContamination.pdf

Should explain it all

UpgradeME · 12 Mar 2012

crockett said:
Should explain it all

Thanks, that's given me a good starting point to find out more!

Several sites seem to say the same thing, that a tight fitting lid and inhibitor should prevent the algae... unfortunetly I have both already (or so I thought). I wonder if the fact that I have modulating flow controls (so lower radiator temperatures) stimulates the growth? Is it more common with weather compensation/modulating systems I wonder?

A search on here reveals Sentinal have previously suggested bleach kills off the bacteria and Salamander suggest using a "10% solution of household bleach" which sounds cheaper than the £25+ Fernox biocide

I'll clean the header out tomorrow with bleach, refill adding more F1 (I have a new bottle spare), I guess if I add a bottle of F1 in the header, there will be LOTS of chemical making it harder for the fungal mould to grow again but will it ever make it around the system or react to any traces of bleach left over?

transam · 12 Mar 2012

Fernox I beleive used to do a biocide specifically for this purpose eg feed & exp tanks ? AF 10 according to my notes , that may be wrong or out of date ???????????

Dan Robinson · 12 Mar 2012

Why not seal the system?

UpgradeME · 13 Mar 2012

transam said:
Fernox I beleive used to do a biocide specifically for this purpose eg feed & exp tanks ? AF 10 according to my notes , that may be wrong or out of date ???????????

It's still on sale, it's the £25 I mentioned above for 500ml of Fernox AF-10!

I've now cleaned it with my £1 bleach (not sure how Fernox can justify their cost!?); the water was still black after I left it overnight to settle, not sure if the black was magnetite or bacteria/mould/fungas but it smelt like stagnent water (The radiators bleed clean water so I'm assuming it's the latter).

Dan_Robinson said:
Why not seal the system?

Besides the fact there will be no F&E tank, are there any other tangible benefits in converting the CH to a sealed system?

I've thought about it before, the only thing putting me off is I have 10mm pipes plastered into the walls downstairs (15mm tails upstairs) in a 16 year old house/plumbing (all copper). Typically, would you say there is a high / medium / low chance of getting leak(s) when converting such a system? (The radiators are all Stelrad Elites)

DeltaT2 · 13 Mar 2012

OMG!! Bleach in your Central Heating system??!!

You know, every second post on here is about additives or power flushing central heating systems!! There's a public paranoia about it. I mean what's wrong with a little algae in your F&E tank?? The chances are that it's there as a result of someone adding too much additives in the past.

As for sealing your system because you've a dirty F&E tank??!! Talk about a waste of money!!

UpgradeME · 13 Mar 2012

DeltaT2 said:
OMG!! Bleach in your Central Heating system??!!

... as recommended by Salamander, Sentinal and others!

Do you know of a reason I shouldn't use it? (It's currently sitting in the F&E, killing off the bacteria for a bit before I rinse it out and re-fill)

You know, every second post on here is about additives or power flushing central heating systems!! There's a public paranoia about it. I mean what's wrong with a little algae in your F&E tank??

The brown stuff was like wet cardboard, breakable into smaller pieces but thick/dense enough to make a nuisance in my microbore pipes / rads / Hex should it find it's way into my pipework... Thats why I cleaned it.

As for sealing your system because you've a dirty F&E tank??!! Talk about a waste of money!!

... hence the question about other tangible benefits!

DeltaT2 · 13 Mar 2012

'Bleach is made by dissolving sodium hypochlorite in water. Hypochlorite is an extremely dangerous and caustic chemical. Extreme caution and good ventilation is needed when making bleach or serious injury or death could result.'

It's not a chemical I'd put in my central heating system!!! In fact it's only companies that make chemicals that recommend you put 'chemicals' in your central heating system!!! In Germany, there's little or no chemicals of any kind put in central heating systems, as in North America they also advocate just plain water in your system.

I wish I had a £ for every knackered circulation pump or combi diaphram that I've replaced as a result of too much additives in systems.

A correctly installed & operating central heating system would never circulate the content of a full F&E tank into it's pipework.

UpgradeME · 13 Mar 2012

DeltaT2 said:
'Bleach is made by dissolving sodium hypochlorite in water. Hypochlorite is an extremely dangerous and caustic chemical. Extreme caution and good ventilation is needed when making bleach or serious injury or death could result.'

I'm using the end product to clean the tank, not making the stuff!!!

In fact it's only companies that make chemicals that recommend you put 'chemicals' in your central heating system!!! In Germany, there's little or no chemicals of any kind put in central heating systems, as in North America they also advocate just plain water in your system.

From my (German) Vaillant boiler installation manual:

Vaillant Manual said:
For long-term corrosion protection, after flushing, an inhibitor suitable for stainless steel heat exchangers should be used, refer to the current issue of BS 5449 and BS 7593 on the use of inhibitors in central heating systems

I agree the chemical companies have a vested interest, however I think there are valid reasons... not forgetting that our (treated) mains water is likely to be chemically different to that in USA / Germany which may also have a bearing on what needs to be added!?

A correctly installed & operating central heating system would never circulate the content of a full F&E tank into it's pipework.

Agreed, however, should that system be drained (pipe burst, radiator removed etc without checking the F&E (there's an external valve for intake) there is potential for the contents to end up in the system so I see this as preventative maintenance.

DeltaT2 · 13 Mar 2012

From my (German) Vaillant boiler installation manual:

Vaillant Manual said:
For long-term corrosion protection, after flushing, an inhibitor suitable for stainless steel heat exchangers should be used, refer to the current issue of BS 5449 and BS 7593 on the use of inhibitors in central heating systems

Of course any boiler manufacturer does need to comply with the UK BS, but hey mate you carry on, add what you like.

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Mould / 'cardboard' like substance in header tank

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