Anti mud and corrosion of old heated floors?

[Christophe]

A few days ago I dismantled the circulator from our (old) heated floors because of a leak from a fitting (which in fact was puffed) and I was amazed at the "corrosion" of the circulator because it was new !

The circulator was assembled in 2007, it already presents approximately 5 mm of corrosion or rather hardened encrusted sludge on the hydraulic part! And 10 mm reduction of passage on a standard UPS circulator well that's a lot (20 to 25 mm of passage). I would even say that it is enormous since we have used heated floors only rarely (ladle 1000h over 3 years).

But obviously old sludge is still in the circuit (25 years). The original boiler was changed in 2005 by the former owner, it was probably completely HS. I had purged and unblocked the PCs 1 by 1 in 2007 with more or less success.

The steel / black elements are fortunately quite rare: circulator, some fittings ... the rest is brass and copper.

In short, all this to find out if there is a "sustainable" solution against the sludge from old heated floors which capture oxygen from the air and corrode everything they can, especially when it contains iron! Solution if possible not chemical ...

On the chemical side, I had heard of hydrazine injection (H2N2 is rocket fuel !!) but it does not please me too much because I open the circuit quite often (change, improvement ..) the proof with this leak ...

Thank you

[swift2540]

Hi,
sorry to disappoint you, but apart from the chemical, I don't really see how to remove "solid sludge" from an installation.
I have used fernox cleaner F3 for difficult cases (completely blocked u-circuit). Then protector F1 after rinsing the installation. But you must leave the protector as long as possible, so do not drain.
They also have an anti-leak that I have used 1X successfully.
On sale in specialized sanitary-heating stores.
This is for sludge removal.

For corrosion, you need 2 things: water AND air (oxygen, in fact).
==> the fact of emptying often, therefore of adding new water loaded with oxygen, accentuates the phenomenon of corrosion
(this is why we use galvanized pipe for drinking water, and even for cisterns).

Apparently, you also have anodic corrosion phenomenon. Copper "eats" iron / cast iron, a less noble metal. Replacing water also accentuates this phenomenon, which is almost non-existent if the water is not replaced.
The solution is to not put the copper in contact with the iron:
- or by inserting brass / bronze parts, for example valves on either side of the circulator (which also makes it possible not to drain everything in the event of replacement / repair)
- or by placing synthetic elements, for example a piece of per-pipe between the iron and the copper.

PS: I suppose that the earth connections are correct and up to standard, because if you have stray currents or earth connections on the pipes, you hit the jackpot

@+

[aerialcastor]

because if you have stray currents or earth on the pipes

I'm not sure I understand the meaning of your sentence, but it's compulsory to connect the copper pipes to earth.





Taken from :http://sitelec.org/promotelec/misalaterre.pdf

[swift2540]

Yes exactly...
It is necessary to connect the pipes to the ground, and not to use the pipes like grounding ...

[Christophe]

Thank you for the info.

Well already there are many (very) many connections to the ground (via a copper cable) of the tubes of the network.

Regarding the iron / copper corrosion a priori there is no iron / copper contact, we always go through a brass part (welded on the copper side).

We can check if there is an electro-chemical problem with the network with a simple multimeter?

I will take a picture of the old circulator for you if I find it: there is indeed a deposit of something "hard" on the iron. It can only be removed by tapping on it with a metal part!

My concern is more to prevent the formation of this sludge than to clean it ... since the tablecloths of the PCs are made with PER pipes without anti-O2 barrier; the O2 concentration only increases and corrosion is inevitable ... and therefore it would ultimately be necessary to remove everything that is iron in the network (and therefore, for example, put a stainless steel exchanger at the level of the boiler with double mandatory circulator).

I think the current sludge is "material" from the old boiler ...

[swift2540]

Well already there are many (very) many connections to the ground (via a copper cable) of the tubes of the network.

So much the better, it's already a good point

Regarding the iron / copper corrosion a priori there is no iron / copper contact, we always go through a brass part (welded on the copper side).

This is another good point.

We can check if there is an electro-chemical problem with the network with a simple multimeter?

Not a clue, proper grounding evacuates these stray currents, and cancels the problem. I don't know any more.

I will take a picture of the old circulator for you if I find it: there is indeed a deposit of something "hard" on the iron. It can only be removed by tapping on it with a metal part!

These are residues of several things:
- the water contains dry residues which are deposited in the long run (those which are mentioned on the bottles of water)
- the water also deposits its limestone (or its rust if ferruginous water)
- assembly greases, solder remover ...
everything comes together and "cooks" gently for years, it becomes very hard.

My concern is more to prevent the formation of this sludge than to clean it ...

Cleaning them allows a better heat exchange (they are insulating, ==> loss of performance pc). This also makes it possible to find a better passage, therefore to reduce the power of the circulator for an equal result.
This also allows the water to remain in a laminar regime (i.e. calm). If you go into turbulent regime, you will have a tendency to increase the proportion of air contained in water.
To stabilize them, only the chemical succeeds, unfortunately. And I don't know how long ...
But changing the water contributes to overall fouling.

since the plies of the PCs are made with PER pipes without anti-O2 barrier; the O2 concentration only increases and corrosion is inevitable ... and therefore it would ultimately be necessary to remove everything that is iron in the network (and therefore, for example, put a stainless steel exchanger at the level of the boiler with double mandatory circulator).

A good solution would be to mount an air separator, for example
http://zusters.flamcogroup.com/pdf/pdf/doc.wln.va.07.v050201.pdf
Look at the "Flamcovent" page.

The installation must also be "under pressure", ie circulator on the outlet and expansion vessel on the return.
If the 2 are on the return, you put the installation in "depression" ==> by venturi effect, you can suck in air through the fittings, without there being any water leak.