Dezincification of CH fittings - time to replace?

[McKendrigo]

Hi,

I've found that the CH was needing topped up fairly regularly, every couple of weeks. Long story short, when getting my go-to guy for CH to check a couple of leaks I found, he flagged up that in general the CH fittings were showing signs of bad dezincification and that given their age they're getting to the point they'll become brittle and liable to start leaking and failing (the house is 55-60 years old and the CH pipework and fittings are either the same age or at least a few decades old). I've attached a couple of photos of fixtures - they certainly look nasty to my untrained eye, I think I can see a crack in one...

The slow loss of CH pressure persists and I've not found an obvious leak, so there must be a slow leak somewhere.

I understand that if this is the case that the only permanent solution would be to replace everything in the system, as all the old fittings will be degraded to some degree and will eventually fail. Almost all of the radiators are ancient too, and I'm minded to just get the whole CH overhauled and have peace of mind rather than constantly patching things up bit by bit for years.

Not got a quote in yet, but just wanting to get some advice before the next step. Is what my guy saying sounding plausible? Any tips for what to ask about when getting a quote or discussing the work to be done?

Thanks!

 

[CountryFan]

I can’t see any cracks. Looks a little like oxidisation as opposed to dezincification. It’s plausible that’s where they could be leaking, but don’t think they need replacing.

 

[McKendrigo]

Thanks for the reply. Here's a close up of what I thought might be a crack - I was going to go and take a better look at it, didn't notice when I was taking the photo.

Is there a way to tell oxidisation and dezincification apart? Anything I can look for?

 

[CountryFan]

Thanks for the reply. Here's a close up of what I thought might be a crack - I was going to go and take a better look at it, didn't notice when I was taking the photo.

Is there a way to tell oxidisation and dezincification apart? Anything I can look for?

View attachment 410415

Ah, that does look more like a crack. Oxidisation/Verdigris is green and usually surface, but can be internal. Dezincification is where the zinc is removed/leached out.

 

[McKendrigo]

Thanks again. Any advice for what dezincification might look like? I'm just wanting to have an idea what to look for so if someone's coming to check the CH and they're pointing things out that I know what I'm looking for.

Also, I would guess there's no reason that dezincification and oxidisation can't both be present at the same time?

Cheers!

 

[Stivino]

There is no zinc in copper, so dezincification will only occur on the brass as it is an alloy of copper and zinc. It has a pinkish appearance.
The green is copper oxide, i.e. copper that has combined with oxygen.

 

[McKendrigo]

There is no zinc in copper, so dezincification will only occur on the brass as it is an alloy of copper and zinc. It has a pinkish appearance.
The green is copper oxide, i.e. copper that has combined with oxygen.

That's great, thanks.

Final questions - to clarify, the types of fittings shown on the photos are brass, not copper? If they're brass, how do they end up looking green too?

Regarding the "crack" in the earlier photo, I had a look again and fortunately it was a bit of fluff that just happened to look like a crack in the photo!

 

[Stivino]

how do they end up looking green too?

Brass is an alloy, it's mainly copper, 70%ish mixed with zinc, 30%ish.