When I flushed & refilled my CH system last year I had to remove quite a wodge of jelly-like growth from the header tank. Luckily it hadn't descended into the pipe work.
Fernox appear to make AF-10 biocide to deal with this growth - I tried to buy some but no-one seemed to stock it and I was advised that most people just add extra inhibitor into the tank to deal with the problem so I did.
I checked the header-tank yesterday and the growth has returned so I'm again trying to buy AF-10. The local Plumbase said they could get some in but I just went to collect it and they'd failed to do so, so now they're ordering it direct from Fernox. I was again told that no-one uses it which is why they don't stock it and that it "old hat".
FERNOX ALPHI-11. A combined anti-freeze and inhibitor which is suitable for protecting heating, chilled water, and solar systems. It helps prevent oxidic corrosion, bacterial contamination and limescale formation. Suitable for all metals
The slime is a "bio-film". See ehp.niehs.nih.gov/docs/1998/106-12/innovations.html
It probably hasn't got into the main circulation pipework because the working temperature is too high for it to survive. It has only proliferated in the stagnant water of the F&E tank, the cold feed and open vent pipes. The organsims responsible secrete a sticky carbohydrate coating which protects them from disinfectants and anti-biotics. Generally, it takes 1,500 times as much disinfectant to kill and disperse a biofilm as a bacterial infestation; I doubt that Fernox or household disinfectants will clear the infestation, some bugs will survive and the bio-film will return in a few months.
It may be Pseudomonas aeruginosa , a very persistent slime that can clog heating or cooling systems. I'm an engineer, not a microbiologists, so I'm open to correction by the microbiologists who frequent this forum. Pseudomonas was in the trade mags a few years ago, having been identified in a number of clogged-up or contaminated commercial systems. The organism was getting in through the fill water and, once clogged, the systems were extraordinarily difficult to clear. It is present in small numbers in the environment and (possibly) in the mains water, like legionella. It is harmless in this form, the problems occur when it is given favourable conditions to survive and multiply. The recommendation was to disinfect the water used to fill the systems, to prevent the system becoming contaminated. I don't know the details, but I think it was low-temperature systems (water treatment, chilled water, heat recovery), rather than LTHW heating systems.
Pseudomonas aeruginosa can cause infections, especially lung infections in cystic fibrosis sufferers, also urinary tract & contact lense problems.
I think I'd look at converting to a sealed system, if your boiler is suitable (i.e., it must have a secondary manual-reset high-limit thermostat), and minimize the lengths of any dead-legs. Check with the boiler manufacturers. Otherwise do some searching for an effective biocide. If you've got plastic pipes, then be aware that polybutylene pipes (e.g., HEP2O) don't like high chlorine levels, chlorine being a common and effective disinfectant ingredient. I think PEX is OK.
good point. I would be a bit cautious about handling it. Bugs in that quantity could overwhelm anyone's T cells.
Chlorine will evaporate in time, but might do something to reduce slime and bacteria population for a bit. I'd stick some copper compund in there, its harmless to your heating system and kills just about everything. CuSO4 should so it. Swimming pools sometimes use Cu and Ag in place of Cl2.
Since its not in the hot section, boiling the water for half an hour would also kill it, fwiw.
A chemical that breaks down the sticky coating may help a lot as well, by removing most of the defences.
Chlorine bleach? But would adding that adversely affect the rest of the system?
I tried to find a source of CuSO4 and failed. Ahhh
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does stock both stabilised chlorine granules & a copper-based 6 Month Algaecide. They're not far from us. Would either of these be Ok? (Wonders, why is any of this necessary in my system??? - what is wrong with it?)
It's not an algae, so an algaecide would be of dubious effectiveness. I'd be very wary of bunging in home-brew chlorine or copper compounds in the hope of killing it. Thery could create corrosion problems, if not flushed out. Pseudomonas was resistant to customized biocides, I wouldn't count on a home-brew toxin. Even if you got the system 100% sterile, there'll be bugs lurking in the environs of the F&E tank, ready to recolonize the water when the chemical's effectiveness have diminished.
The slime isn't in the circulation pipes and isn't causing a problem. If you must use chemicals, I'd just disconnect, drain and treat the OV, feed pipe and F&E tank.
I still think a sealed system is the best fix for this. If any bugs get established in the expansion vessel, they won't get out.
Sorry I don't know more about the appropriate chemicals.
I just did a search of Google Groups and found there is a group called "bionet . microbiology . biofilms"! I kid you not. Someone there might have an answer.
I suggest you call the Fernox help line for some definitive advice.
017990550811
The reason why contamination of the feed and expansion cistern has occurred should be identified and the cause remedied otherwise contamination will reoccur and the following stages will be a waste of time.
The system should be drained and thoroughly flushed out.
The header tank thoroughly cleaned manually, ( face mask eye protection rubber gloves) wipe internal surfaces with a rag soaked in strong bleach solution.
The tank then should be flushed to remove ALL residual bleach
The system should be thoroughly cleaned out, then disinfected with biocide ( ask Fernox for their recommendation),
Then again thoroughly flushed, and fully drained
Then and ONLY then should sufficient fresh inhibitor/corrosion proofer be added.
Yes, time consuming but thoroughness will be rewarded with a trouble free operation for years to come.
replying to dave , Geoff wrote: Hi Dave I have been an engineer for 30 years. I use it on every underfloor heating system that we instal. I find that if you power flush a system with a header tank it usually gets infected with the sludge usually pseudonomous, which is bad for your lungs and ears so wear a mask etc. Drain the tank with a hose pipe bye siphoning it into a toilet or something else, scrub the whole thing out ball valve and float, underside of the lid. When it's all clean drain it down put AF10 in a smal plant sprayer and spray all of the inside of the tank , spray some down the overflow all around the ball valve etc ,wipe it all over with a cloth being carful not to miss any where. Then wait 10 minutes refill tank wash it all around then drain it again. Then refill but add two half ltr bottles of theAF10 and leave full. I then ad another bottle or two to the system. Do not drain the tank through the system!! I hope this helps, or ring fernox
He had this issue 12 years ago, and is most likely long gone from here. This is news:uk.d-i-y, not a website, try a newsgroup portal or client that can claim basic sanity.
What's so magic about gallons of af10 anyway? Copper sulphate is vastly cheaper, and any CH system with copper in it is going to end up with copper compounds in the water anyway.
This might assist you with posting to a newsgroup, albeit through a website:
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