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Oct 16, 2018
46
6
8
London
Member Type
DIY or Homeowner
Hi All,

We have a Viessmann 222-F BT2B Combi Storage Boiler - it was installed in 2019 so about 6 years old. A Magnaclean Professional 2 Filter was fitted at time of boiler installation. A Power Flush was also done & a water softener fitted.

The boiler has been serviced every year without fail & the last service was about 3+ weeks ago. At time of servicing the Magnaclean filter is checked, cleaned & new Adey MC1+ Inhibitor always added.

We have 10 Radiators in the house - all double panel except one & six are less than a year old, two are about 2 years old, one about 8 years old, one about 15 years old & one about 20+ years old. There are 3 Towel Rads - two about 8 years old & one about 12 years old.

We used to find some sludge on the Magnaclean filter not an excessive but still a surprising amount considering mainly new main Rads, system had a power flush & yearly inhibitor added.

We had a boiler issue last week whereby it was not working & no hot water or heating. Viessmann sent an engineer round to fix & he changed a pump at the back of the bottom section & behind the top of the water storage tank. He still experienced some problems but was able to identify the issue as crud in the plate heat exchanger which, as a novice had me quite shocked.

I explained to him, that the Magnaclean 2 Pro was fitted just for this purpose to collect the sludge & debris so how could the Plate Heat Exchanger possibly be blocked & especially badly enough to cause the boiler to have issues & surely the Magnaclean Pro 2 would have have collected it as it was never fully packed with sludge on the magnet - it just does not nake sense to me at all.

He just said the filter collects some stuff but not all of it - but again, this did not make sense to me - I can understand if the there was so much sludge collected in the Magnaclean Pro 2 that there was no more room for it to collect any more of it but this was not the case & also, I was not expected much sludge at on a cleaned system with mainly new/newish rads.

The Viessmann Engineer said he did me favour as blockages in the boiler are not covered under warranty so I got lucky this time but probably not again if the same happens. The guy who does my servicing told me that if the Viessmann Engineer had not fixed the issue, it may have cost around £600-£700 to rectify which is awful lot.

I really wish to avoid this issue happening again & really want to look after my boiler so it is always in peak & healthy condition as it cost a lot of money & I expect repairs on it to be quite pricey (although it still has 4 years warranty remaining) but as mentioned, blockages are not covered.

I asked my service guy if one can do a Chemical Clean with say Sentinel X400 over say a week or so while the boiler is still in daily use & if easy to do - he was of the opinion that this & even a Power Flush will get the system "cleaner" (& no way to tell how much cleaner) but not fully clean? What are all your thoughts?

In view of this, what can be done to ensure this issue does not happen again & the plate heat exchanger (as well as the entire system) always stays clean?

Many Kind Thanks!

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Thermal Imaging Of Some Rads:

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Last edited:
We’re the radiators flushed before fitting as depending on manufacturer they leave a lot of rubbish in them

Worth definitely if you can dropping the water out and adding some x800 for a week then drain and re dose with Chems

Most chems manufacture well test the system water to see what’s going on eg sentinel etc
 
We’re the radiators flushed before fitting as depending on manufacturer they leave a lot of rubbish in them

Worth definitely if you can dropping the water out and adding some x800 for a week then drain and re dose with Chems

Most chems manufacture well test the system water to see what’s going on eg sentinel etc

Hi ShaunCorbs,

Thanks for replying! There was a Power Flush & Magnacleanse done at time of boiler install but if you are referring to the newer radiators that were fitted recently, then no - the builders just took them out of the packaging & fitted them.

When you say dropping the water out, do you mean drain down the system? In my naivety, I presume you do not mean just putting the X800 in the system on it's own (no water?).

If you could be kind enough to explain to me a detailed step by exact step in novice & layman's terms that would be really helpful as I am just a homeowner. Is this something you recommend a novice can do?

What is the difference between X400 & X800 - I think I read somewhere that one of them needs special neutralisers afterwards to get rid of the last remnants of it otherwise it can damage the system?

This may be a bit of a daft question but would adding another Magnaclean Pro 2 help?

Many Thanks!
 
Hi All,

I came across this video by a plumber who was comparing filters & cleaners & as an experiment, he had a filter on the normal return pipe but also one on the flow pipe as well.

What he found was that the filter on the return pipe (as per standard installation) picked up the much smaller particles but surprisingly, the filter on the flow pipe picked up large chunks of debris - the type that would block up heat plate exchangers.

This has got me wondering since my Magnaclean Pro 2 caught sludge but not massively by any means - could it be that my boiler heat exchanger was blocked by debris that was in the flow pipe? This might explain why it got blocked?

I am wondering then, if it might be an idea to get another filter - something like the Magnaclean Micro fitted on the flow pipe so that way the Magnaclean Pro 2 can catch the smaller particles & the Micro 2 can catch the much larger ones as in the video posted below?

Just an idea & would welcome all your thoughts...

Many Thanks

View: https://www.youtube.com/watch?v=LpZZE5Lz3MA
 
Hi ShaunCorbs,

Thanks for replying! There was a Power Flush & Magnacleanse done at time of boiler install but if you are referring to the newer radiators that were fitted recently, then no - the builders just took them out of the packaging & fitted them.

When you say dropping the water out, do you mean drain down the system? In my naivety, I presume you do not mean just putting the X800 in the system on it's own (no water?).

If you could be kind enough to explain to me a detailed step by exact step in novice & layman's terms that would be really helpful as I am just a homeowner. Is this something you recommend a novice can do?

What is the difference between X400 & X800 - I think I read somewhere that one of them needs special neutralisers afterwards to get rid of the last remnants of it otherwise it can damage the system?

This may be a bit of a daft question but would adding another Magnaclean Pro 2 help?

Many Thanks!

Was inhibitor added ?

Tbh have a look at plumberparts for a video on draining etc
 
Was inhibitor added ?

Tbh have a look at plumberparts for a video on draining etc
Hi,

Yes, since we mainly have double panel rads - two bottles of Adey MC1+ each year at time of servicing when filter is cleaned - will have a look at plumberparts video

Thanks!
 
We’re the radiators flushed before fitting as depending on manufacturer they leave a lot of rubbish in them

Worth definitely if you can dropping the water out and adding some x800 for a week then drain and re dose with Chems

Most chems manufacture well test the system water to see what’s going on eg sentinel etc
It is always the plate heat exchanger that gets blocked on the Viessmann boilers, some of their engineers are very poor as we've found out in the past
 
It is always the plate heat exchanger that gets blocked on the Viessmann boilers, some of their engineers are very poor as we've found out in the past


Hi,

May I ask, why would that be the case generally & especially with a Magnaclean Pro 2 filter installed? This really interests me & I would really like to know!

Out of interest, what are your thoughts on placing another filter on the flow pipe as per in the video above? I ask since you say Viessmann Boilers are known to get blocked heat exchangers?

I have have since had the system cleaned with Sentinel X800 & after flushing, added 2 bottles of Adey MC1+ Inhibitor added so the system should hopefully be clean as it could be under the circumstances.

I have found Viessmann Service Engineers to be pretty good in all honesty (the ones that I have had anyway) but Viessmann Technical Department is absolutely shockingly bad - they really are - arrogant & useless & dismissive to customers/enquiries to be honest!

My Plumber said this to me:

Worcestor Bosch = Worst Boilers - Best Customer Service
Vaillant = Good Boilers - Good Customer Service
Viessmann = Absolute Best Boilers - Worst Customer Service!

Many Thanks!
 
Hi,

May I ask, why would that be the case generally & especially with a Magnaclean Pro 2 filter installed? This really interests me & I would really like to know!

Out of interest, what are your thoughts on placing another filter on the flow pipe as per in the video above? I ask since you say Viessmann Boilers are known to get blocked heat exchangers?

I have have since had the system cleaned with Sentinel X800 & after flushing, added 2 bottles of Adey MC1+ Inhibitor added so the system should hopefully be clean as it could be under the circumstances.

I have found Viessmann Service Engineers to be pretty good in all honesty (the ones that I have had anyway) but Viessmann Technical Department is absolutely shockingly bad - they really are - arrogant & useless & dismissive to customers/enquiries to be honest!

My Plumber said this to me:

Worcestor Bosch = Worst Boilers - Best Customer Service
Vaillant = Good Boilers - Good Customer Service
Viessmann = Absolute Best Boilers - Worst Customer Service!

Many Thanks!

Depending on the age of the boiler it could have the rubber primary hoses (later on Viessmann upgraded these to copper due to problems yet they say they haven’t had any 😂)
There not smooth on the insides and go hard so collect smoo let’s say and dumps it into the plate as it’s the nearest thing
 
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Depending on the age of the boiler it could have the rubber primary hoses (later on Viessmann upgraded these to copper due to problems yet they say they haven’t had any 😂)
There not smooth on the insides and go hard so collect smoo let’s say and dumps it into the plate as it’s the nearest thing

Hi,

Yes, I my 222-F has rubber hoses & copper hoses but do not know if the rubber ones connect to the plate heat exchanger - can you tell from the image below?

If it is the rubber hoses deteriorating & then rubber particles then blocking the heat plate exchanger then that would be a Viessmann issue (good to know for future warranty claims) & I guess then placing another filter on the flow side would not then negate the issue...

Many Thanks!

Screenshot 2025-08-04 at 16.28.06.png
 
Hi,

Yes, I my 222-F has rubber hoses & copper hoses but do not know if the rubber ones connect to the plate heat exchanger - can you tell from the image below?

If it is the rubber hoses deteriorating & then rubber particles then blocking the heat plate exchanger then that would be a Viessmann issue (good to know for future warranty claims) & I guess then placing another filter on the flow side would not then negate the issue...

Many Thanks!

View attachment 96495

Yes it does
 
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