Viessman boiler kettling after 2 years trouble free service

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John I think mehran's picture is showing the "shed" corrosion inside the window!
It would be interesting to get some of that stuff under a microscope and do an analysis. I bet it's not just Fe304.

And another misunderstanding possibly - the original poster "moving the cold feed" may have only involved a filling loop? Otherwise, yes the advice/alteration he's been given will kill his system by pumping over .

Original poster - as you've gone part way with the filling loop - go the whole hog and seal the bloody system. You may need some bits from V,
(probably not, I can't remember) and a pressure vessel & gauge, but you'll put the pressure and therefore the boiling point of the water up and squash air into solution so it won't kettle so much.
You could try Boiler Silencer, if the thing isn't too fussy about it. That also puts the BP up a bit.
You could clean it out with a phosphoric (FX-2) or Citric/malic (DS-40)acid type descaler. That might invalidate your warranty though V would, typically, already have terminated it.

The diagram I posted is "unconventional" to say the least. It's probably for your boiler JohnD - is yours plumbed like that? If so what's the static head?

If it was "Quite Wrong" of me to suggest what I did, how **** wrong is it of the sly git at Viessmann to not acknowledge their error or at least that there had been a change? Perhaps it's all you can expect of a worm who spent ages saying how bloody marvellous his own boilers were, without admitting who he was.
 
Is there a window in mine?

View media item 4841
or is that not so much a window as the port where the water pipe is connected?

do you suppose a filter would trap those particles?
 
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It seems to be going from worst to worse! Not being helped by posting his problems on multiple advice sites! Tony

just trying to gather as much info as possible to take a methodical faultfinind approach rather than attacking it randomly, cheers ;)
 
Yes, but its the same people who frequent both sites!
 
sorry JohnD :LOL: the picture is off a viessmann 200w(it uses the same heat exchanger design)

on your boiler i would of pulled off this pipe:


to show the flow exit port of the heat ex-changer so them black bit in my picture are this sort of stuff:

 
Yes, but its the same people who frequent both sites!

thanks for the input, might better if you just answer on one then....... ;)

anyways, update for future ref for other people who have similar issues, thats what web forums are useful for......... trying to help overcome problems/issues.

the system has been restored to its 15year old original (pre-kettling!!!) configuration, ABV, C/F, pump, etc etc. The C/F mod to the return I added has been retained but with the addition of gate valves so I can now cold fill either or when the system is running. The filling loop is still there and only used as ........err..........filling. This has helped with filling and shifting any air locks in the system as yesterday there was nothing to bleed out of the radiators during startup
I've dosed the system with inhibitor and noise reducer (x100 & x200) and see how it settles down.

So after all that, early indications are its reduced but not elminated the kettling, we'll see how it settles down in the next week or two before further investigation.

On a side note, I powerflushed the boiler at source again yesterday for over two hours with Fernox F3.

After this and while the boiler was disconnected I rigged up a "calibrated" bucket to measure the actual flow through the boiler, using the system pump (the CH pump not the powerflush pump) "old school".
I used a number of different experiments, different ABV settings, zones open / closed, pump speeds etc etc, to simulated worst case scenario, just to satisfy my own curiosity.
The boiler requires min 200L/H according to the manufacturers info, so as this is supposedly a flow issue, it should be more than happy if this is the case. Varies from 350L/H upto 1200L/H.......

Also noted on the differential thermometer I rigged up that the indicated temp on the boiler control panel varies between 7-10deg higher than the actual output measured on the flow outlet pipe. The flow/return temp diff is about 6-10deg kettling or not

PS
Agile i'll post it on t'other forum mate just to update the thread there, some of the thread posters may read both, but lurkers/info gathers may not??? try not to wind yourself up too much about it. Thanks for your input ......
 
If, as I believe, the noise is caused by air bubbles lurking at the top of the coils, I'm puzzled by all the time and effort you have spent not dealing with them.

Adding fresh water will of course introduce more dissolved air.
 
If, as I believe, the noise is caused by air bubbles lurking at the top of the coils, I'm puzzled by all the time and effort you have spent not dealing with them.

Adding fresh water will of course introduce more dissolved air.

hard to confirm though, what form or air?? induced/leakage air or dissolved air being released at the hottest point due to lack of heat transfer????
air how it got in there?? who knows, crud build up?? possibly?? just trying to cover as many things (methodically) in the time space available...

as I said the kettling has reduced but not eliminated, hopefully when its settled down and the x200 has had a bit of time to do its thing........who knows, watch this space. thanks for your input
 
On mine, after a great deal of puzzlement, I turned the pump up to max temporarily, and the noise went away. It's my belief that the air, or whatever it was, got blown through by the increased flow. I didn't do any other work. The shape of the coils looks like air would tend to gather at the top. The noise only occurred when modulated to 4 or 5 bars which seldom happens.

I looked up my old thread and I see I left the pump on max for three days.
 

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