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Discuss Black flow meters on new CH system in the Plumbing Forum | Plumbing Advice area at PlumbersForums.net

LE4R

Messages
8
Hi

Is it normal to have very black UFH flow meters on a relatively new manifold (see image)? (Note the two clear flow meters on the LHS are for circuits which are not yet operational, so no water flow through them as yet.)

Background is that I have an unvented system boiler CH system comprising an oil-fired boiler, ground floor Omnie UFH, and upper floors using Stelrads (compact range), one brass towel rad and a one steel towel rad.

The entire system - including boiler, rads and all pipework etc - was a brand new fit-out as part of a house renovation just over 1 year ago. Nothing was kept from the old system. So I was astonished to see how dark the flow meters were yesterday when looking for something in the cupboard where the manifold is.

Incidentally, I realised during the installation that the plumber doing the works had guys on the job who were not as attentive as perhaps they should have been. I asked a number of times about inhibitor being put into the system to prevent corrosion, and was assured this was done - but am now sceptical based on this image.

Questions - are my suspicions reasonable? Do I need to be concerned by this? And what action would you suggest to diagnose and fix?

Apologies if I missed any key information, please let me know if so and I will try to provide.

Many thanks

Laurence
 

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LE4R

Messages
8
Sorry, forgot to mention - yes, sealed system with expansion vessel.

I've taken a look near the boiler and HWC, and there's a "TF1 Omega Filter", made by Fernox - quick google suggests that it should stop corrosive elements damaging the boiler pump, but would the blackness in the flow meters indicate an underlying problem none the less? If not, what do you think could be the cause?

TIA
 

ShaunCorbs

Staff member
S. Mod
Plumber
Gas Engineer
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29,442
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No not normal also no cap end on the first one on the left that’s not good
 

exedon2

Esteemed
Messages
645
As above not normal at all,was filter cleaned when boiler serviced? Is system holding pressure without regular top ups?
 

LE4R

Messages
8
I will ask the question about the filter being cleaned - engineer who did the service (different from the plumber who did the install) did this only just before Christmas.

According to the valve on the expansion vessel, the system is holding pressure pretty well. I think there has been a very small drop recently (maybe 1.5 bar to 1.3) but I considered trivial.

Earlier in 2021 we had quite a few depressurisation events, necessitating a mains top-up. When I flagged this to the plumber and got them out, they came to test the system, and tracked a leak but they told me it was HW pipe, not CH, which they remedied. Then put the system under about 4 bar pressure for an hour and it held, so considered it to be sorted. When I asked the plumber why then the pressure leak, he told me it must have been an air pocket that had caused the drop... in any event, since then, it's been pretty good.

Incidentally I've been pretty good checking the rads when heating comes on to ensure they're bled.
 

exedon2

Esteemed
Messages
645
If you in essence had the system refilled several times was inhibitor added at the time?
I suspect that's when the corrosion took place.
To be blunt the idea that repairs to the hot water system stopped a leak on heating is very odd .
Do you have a hot water cylinder?
 

LE4R

Messages
8
That's what I'm now wondering - when they did the system check, following the leak, perhaps inhibitor was not re-added...

Agreed re the answer about the HW leak and impact on the heating system, but the answer he gave about small air pockets causing a possible earlier drop in pressure seemed possible, if not likely.

Yes, there's a HWC, positioned right next to the boiler.
 

LE4R

Messages
8
ok, thanks - hard to know when it's not your world and you're reliant on an 'expert'.

So, upshot is it's almost definitely corrosion and needs a flush and new inhibitor. Nothing else it could be?
 

exedon2

Esteemed
Messages
645
Sealed system now holding pressure get a decent flusher through it get it clean add inhibitor.
Then have a crack at idiot who told you a heating system losing all its water was caused by air pockets or a leak on hot water!
 

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