Manky Gunk in F/E Tank!

[Schmill]

Ok, the title sums it up really, but here is some background

Pumped Primary, open-vented system. Indirectly heated DHW.

Last year my heating system had issues with various rads not getting warm etc. When I tried to clean the system the water that came out was black, so I ran some X400 through it for about 1 month and flushed out all the black water until it ran clear.

I then refilled the system with some X100 and all seemed well... for a while...

Due to adding a towel radiator in the bathroom I then had to drain the system again early this year.
When draining, the water seemed murky again and when fitting the towel rail I found that some of the 22mm pipework was quite encrusted on the inside with black deposits (iron oxide I guess). The worst pipe was replaced, and when I refilled I also added X800 (as I believe that is a more agressive cleaner). The circulation pump was set on it's highest setting and the system run with all valves open ensuring good flow round the whole system.

After some period of time I again drained the entire system, flushed the whole thing until the water was clear, then refilled the system adding X100, and ALSO X200.
I have not used X200 before, but as I live in a hardwater area I was advised that it would help to stop calcium build up in the boiler.

This was around 16th February.

-----------------

Over the last 2 weeks or so the system has seemed to get an increasing amount of air circulating in it. I have tried bleeding the radiators and there doesn't seem to be any air in them, but when either the DHW is being heated, or the CH is running I can hear the air pockets circulating and thrashing through the pump in the airing cupboard, and I can hear it gurgle through the boiler downstairs as well.

This evening I had a bit of time to take a look at it, so tried the 'jam-jar over the vent pipe' in the loft, whilst my wife switched the pump on and off, and sure enough the water level in the jar dropped and raised (+ bubbles) in synch with the pump being switched on and off so that seems to be ok.

However when I removed the cover from the F/E tank this is what I was faced with:

F/E Gunk 2011-03-28

• Schmill
• 28 Mar 2011
• 1

F/E Gunk 2011-03-28

• Schmill
• 28 Mar 2011
• 1

F/E Gunk 2011-03-28

• Schmill
• 28 Mar 2011
• 1

Bearing in mind that I scrubbed this tank clean before I refilled last time (about 6 weeks ago!), any ideas on what on earth this manky white gunk is, and where it has come from?
Recommended course of action? Presumably I'm going to need to bail all that out and flush the system through again?
Could this be caused by the X200? It is the only thing that I've added differently to usual?
Could it be this gunk, (or rather whatever reaction is creating it), that is causing the air build up in the system?

Thanks for any info / guidance!

 

[JohnD]

your description is vague.

Is it white slime? Is it a crust of fungus?

what depth of water is above the exit pipe near the bottom? the float looks as if it is sticking out of the water.

 

[Schmill]

Appologies, I've not actually touched it yet, but the jam-jar did when I was testing the vent.

It not a fungus like crust, nor would I class it as slime. Perhaps more of a 'scum'. Like if you left water in a basin that had had a bar of soap in it, or say a sink of washing up water that had washed greasy dishes.
Yeah, definitly a 'scum' would be the best description, if you want to know anymore than that then I'll go back up tomorrow and dunk my hand in the goop!

Not sure on the depth over the fill pipe, but it doesn't seem any deeper or shallower than usual. I'll have to measure it to actually give you a figure for it.
Is there a depth that is recommended?

 

[JohnD]

a couple of inches will do. To my eye it looks very shallow.

If you have bacterial slime or fungus crust, clean it out thoroughly, scrub, wipe over with bleach all surfaces including lid and float, buy a bottle of Fernox AF-10 Universal Biocide (it is expensive) and add half the bottle after refilling the F&E (so the F&E holds the max concentration, stir it in, splash it over the float and arm, sponge the lid with it. You may have to get a proper plumbers merchant to order it for you. Keep the other half bottle to add when you get a recurrence, or if you have to drain or refill the F&E and it gets diluted.

Once you have got an infected F&E, the infection will always be present. Do any other cleaning or inhibiting work before you add the biocide as it is so expensive. There might be some other equivalent product but I don't know one.. Fernox is a top brand.

You seem to be getting a lot of black sediment. Can you afford an extra £100 or so for a Magnaclean or Spirovent? The big magnet in a plastic Magnaclean is very effective at trapping black sediment, but the product build of the brass Spirovent is much better.

Look for a bleed point near the pump and/or cylinder and/or boiler, probbaly on a vertical stub pipe. There may be an automatic valve that is clogged or jammed with sediment. Do this before adding AF-10

 

[Schmill]

So if it is slime or crust it will be bacterial?
From what you have said I do hope it is neither of those, it didn't seem to smell at all, which I would have thought a bacterial infection would?

As you recommend the Fernox AntiBac, is that also the brand you would recommend using as a cleaner and / or inhibitor as well? I've always used Sentinel, but open to advice

I must admit I have been considering getting one of the magnetic capture devices. Magnaclean was the one I have heard the most about, but was wondering if one was preferencial over the other.
Can they be fitted on the flow from boiler, as I don't have much space in my airing cupboard, and practically zero access to the return pipework.

Whilst we are in the airing cupboard....

Old Pipe Layout

• Schmill
• 28 Mar 2011
• 3

There are now some slight changes to this (a feed to the towel raditor after the pummp but before zoning valves, and the cold feed pipe is now at 45 degrees rather than at the slightly-not-horizontal-in-the-wrong direction state it was in before that ALWAYS got airlocked!).
However you can see the stub next to the hot water cylinder. This has a manual bleed valve in the top which sometimes has some trapped air behind it.
Would there be any benefit to change it to an auto-valve?
Can it be done without too much hassle?
What is invovled?

Thanks

 

[JohnD]

I almost always use Sentinel chemicals (I am a householder not a pro) but the only effective biocide I know of is the Fernox one. I think when I got it they said it was compatible. Automatic valves have a reputation for clogging.

the cleaning devices are supposed to go on the return to the boiler, to reduce the chance of sediment getting into it. Once you fit one, you can add X400 and leave it in - it does not have to be removed, but over time it loses its power so the sediment would settle again. However if you have a device to trap it, it can't. Wherever you put the device, it will be a lot better than not having one.

A Magnaclean only traps black particles, which in my experience are the most common, and can collect a spectacular amount. However the valves ands cap sometimes leak which is why lots of pros no longer fit them. The makers must be wishing they had cared more about build quality than about profit, but it's too late for them now. £100 for a plastic canister with a magnet in it, and some cheap valves, might have been OK when they had no competition. Now we all want a better product.

 

[DP]

Schmill, you may want to look at the float valve position in relation to other fixings in the F&E cistern.

 

[Schmill]

I almost always use Sentinel chemicals (I am a householder not a pro) but the only effective biocide I know of is the Fernox one. I think when I got it they said it was compatible. Automatic valves have a reputation for clogging.

Aha, cheers for clarifying that, and I guess I'll stick to my manual one then, after all it shouldn't need bleeding THAT often

the cleaning devices are supposed to go on the return to the boiler, to reduce the chance of sediment getting into it. Once you fit one, you can add X400 and leave it in - it does not have to be removed, but over time it loses its power so the sediment would settle again. However if you have a device to trap it, it can't. Wherever you put the device, it will be a lot better than not having one.

I thought that might be the case In order for me to connect to the boiler return after the cylinder and central heating and bypass /towel rail connections it would have to be under the floor in the bathroom somewhere, (or perhaps on some pipework that must be in the kitchen somewhere, but that I am yet to discover).
I suppose I could fit it on the flow, and then move it at a later date (perhaps when the boiler is replaced or something), I'll check with the manufacturer(s) I guess

A Magnaclean only traps black particles, which in my experience are the most common, and can collect a spectacular amount.

From this I assume that the Spirovent uses a collection method other than (or as well as) magnetic then? I shall go and have a read, any idea if they are as good at removing the black particals as the magnaclean?

Thanks for your responses

Schmill, you may want to look at the float valve position in relation to other fixings in the F&E cistern.

Can you elborate what you mean by this please? Does something appear wrong?

 

[JohnD]

I've used both Magnaclean and Spirovent. Here you see a modest amount of the black sludge collected from my mum's very old heating system after a week of running (this is after it had already been flushed and X400'd)

View media item 12015 . . View media item 12016
and here are the few particles collected from my own system, a week after the new boiler was fitted and the system had already been powerflushed. The Spirovent works on a vortex and labyrinth trap, a bit like the way dirt drops down inside a Dyson vacuum cleaner, so it does not need a magnet. However on the latest version they have put one at the bottom of the vortex where it can hold the stuff that has already fallen through. IMO this is just a marketing gimmick.

View media item 3406 . . View media item 3783
It is no good putting the device out of the way or under the floor, as you have to remove the dirt it has trapped periodically.

 

[Schmill]

Thanks for the detailed response.

Sounds like they are both taking features on from the other then.

Seems the debris filtering spirovent is actually called a SpiroTrap (the 'vent' only removes air?) and uses the vortex you describe to remove particles, but in the latest version they have added a magnet to it (although it seems to not be removable, so I'm not sure how well that will work?!)

The Magnaclean on the other hand seems to be good for removing the black sludge, and has greater capacity, and now in the latest version 'TwinTech' they have added some kind of mesh filter in order to remove the non-magnetic particals too.

At the moment I think the Magnatec one is winning me over purely because you take it apart to clean it, whereas the spirotrap you seem to have to 'trust' that the water coming out of it when you open the drain tap will carry the dirt out.

Seperate to that, I'm still intrigued what caused the gunge in the tank though in such a short time. I've e-mailed Sentinel too, just on the off-chance, asking whether they are aware of any reaction that might cause it.

 

[DP]

the cleaning devices are supposed to go on the return to the boiler

I would strongly suggest more advice be sought regards positioning of the aforementioned cleaner on an open vented system. On a system or a combi boiler, return is indeed the best place to fit the filter unit, but on an open vented system similar position may well be hazardous.

If you look at the header tank, the position of the overflow is incorrect... It should be below ball valve discharge point i.e. the valve should not submerge when overflow takes place.

 

[ade2k]

Why dont you just seal the system and put a expanstion vessle and blow off valve on it. Check with manu if you can seal the boiler first.

 

[Schmill]

I almost always use Sentinel chemicals (I am a householder not a pro) but the only effective biocide I know of is the Fernox one. I think when I got it they said it was compatible.

Apparently Sentinel now do their own Biocide, X700. Don't supose you have used that though so it's effectiveness is unknown

Why dont you just seal the system and put a expanstion vessle and blow off valve on it. Check with manu if you can seal the boiler first.

You make it sound so simple!

 

[DP]

indeed system can be sealed, but at a price. Any weaknesses in the system will be revealed due to higher working pressure.

 

[Schmill]

Just as an update, not had a chance to get any biocide yet, but air in the system was getting so bad that last night I did the following;

• Sealed off FE tank with blanking plug.
  Bailed out and washed the FE tank.
  Refilled with cold water and bailed out again.
  Refilled & removed the blanking plug, then allowed it to drain through for a while to a downstairs radiator.

Hopefully be able to do better this coming weekend, but in the mean time hopefully I'll be able to see if there is some kind of return of the grottyness.

When bailing it out, it wasn't crusty, and it wasn't slimy. It was more of a 'flock' (you know when a solid clumps together in a liquid). Not sure if that makes any difference, but I thought I would let you know.

If you look at the header tank, the position of the overflow is incorrect... It should be below ball valve discharge point i.e. the valve should not submerge when overflow takes place.

I had a closer look last night, and this is definitly wrong then
In order for the overflow to actually 'operate' the ball valve has to be completely submerged, the inlet is pretty much completely submerged, and even the end of the vent pipe is under the surface of the water.
Also through my experimenting (removing the ball float from the valve) it seems that the inlet can fill the tank faster than the overflow can empty it, which I'm going to presume is not a good situation to be in if the ball valve should fail!
So I should lower the overflow, (I'm presuming I can get a blanking plug for the old 'hole' that will be left in the tank?). Should the overflow also be a larger bore pipe than the inlet? To be honest the overflow from both this and the main water storage tank both scream of 'bodge', or at least bad workmanship