UFH Water quality and possible valve leaks

[BenH]

Trying to solve a little mystery to do with minor leaks from manifold valves. Attached image shows the valve (new) and the arrow shows the point of leakage. It seems the internal seal of the moving pin has deteriorated over time. May I add that the valve is not stuck, its moving freely.

Its a mixed system, 6-7 years old, and a number of valves were already affected by this kind of leak 3 years ago. At the time I replaced 3 leaking valves with brand new ones and the leaks stopped. Untill now... A new leak - on same manifold - can be seen in one of the loops. No such leaks (yet) in any other manifold.

As per glass flow-meters the water is dark brown in most loops of the said manifold.

I am led to believe that quality of water can be an issue with longevity of the seal inside these valves and that a more thorough approach would be to clean the water (total renew; a flush, clean, inhibit, biocide, testing) is better than just keep replacing a leaky valve with a new one.

A question: is the water causing this?

Is it the metallic oxides (that normally come from towel rails and radiators which we have 3 of each connected to the system) that attack the seal or is it a biological contamination (bacteria, algae) that is to be blamed?

I have contacted 2 local firms and they were not too keen on a power flush of an UFH system, one of them said a power flush can potentially do more harm than good and suggested not to do one unless the system is not working properly. Other than this minimal leak the system works great!

I can replace the leaking valve without a flush to system (and maybe dose with some biocide?) this would be a one hour job - end of story (for few years, I guess). OR, do I better investigate it further:
-why the water seem to be getting brown (is it metal, or bacteria?)
-what causes some valves to leak?
- flush, yes or no? if yes what's the best way (the entire system, or just this manifold?)...etc.

Not sure how to take this further.

Thanks in advance!

 

[Rob Foster]

Magnetite can be like liquid sandpaper, I would look here first.centralheatking

 

[BenH]

Yes, magnetite CAN be the cause, the question is can I confirm this is the case. Does brown, colour is like Redbush Tea , in flowmeters mean presence of magnetite? If so do I need to flush the system?

A MagnaClean Filter was fitted on the return pipe 3 years ago, and it does pick small tiny BLACK particles, not huge amounts of it though. All I can see is few black rings of the plastic cover of the magnet.

BTW, the MagnaClean sheath (grey plastic) seem to be stuck to the magnet and does not come off easily - making washing the dirt of a bit messy, how do I get it off the magnet?

Does anyone have experience with a Sentinel SystemCheck ?
https://www.sentinelprotects.com/uk/products/sentinel-systemcheck

 

[oz-plumber]

From my experience, all the water tarnishes in system where you have UFH and radiators connected.
As for the leaking seal, just replace. You could have got a manifold with dodgy o-rings - you wouldn't be the first.

As for contacting the manufacturer, you will most certainly get
'we've never had that problem before'

 

[BenH]

It seems like the consensus is that in UFH dirty water does not equal problems (leaks). So this time we’ll just replace the valve and see how long it lasts before going for any water renewal.

 

[Rob Foster]

It seems like the consensus is that in UFH dirty water does not equal problems (leaks). So this time we’ll just replace the valve and see how long it lasts before going for any water renewal.

I have always thought that a good intermediate heat exchanger would be ideal to protect the really vulnerable
parts of ch systems such as UFH, even it it is a sacraficial unit every few years ...but thats
an Api 2006 (my design company) idea bubble.
centralheatking