Black onyx

Rich Swatton_2

Can I bring this discussion up again?
Has anybody seen sludge or rusted pumps in black onyx systems

hot_rod

How old is the system? It sure looks like O2 is getting into the system, to cause that much corrosion.

Is it taking on fill water due to a possible leak in the system?

Better get a good power flush going, before it clogs up the arteries.

Rich Swatton_2

The system has totally failed
Closed system
Onyx used for radiant floor application. Installed new pumps 14 months ago installed Fernox cleaner and conditioner same results.

kcopp

Oh yes.... I have pix too.

kcopp

Here are a few

kcopp

No mater what they say I look at that tubing as a non barrier product. I flush it and treat it w/ fernox or rhomar. A caleffi magnetic separator is a good plan too...
Can you flush w/ high pressure water?

kcopp

This same customer is talking ripping the whole floor of tubing out.... I told him that was way overkill. I am recommending a couple shots of Fernox one after another and then add a caleffi air separator/ dirt sep w/ the magnet finished then it w/ 2 bottles of inhibitor.

hot_rod

You need to get some serious flow through tubes or pipes with heavy sludge. Calculate the loop or piping to be flushed and then use a gpm- fps calc sheet to see what you need to flow that velocity. Try to get 5- 6 fps to move solid particles.

Google gpm/ fps there are a bunch of free online calc tools. This chart get you in the ballpark.

It's rare that just a 1/2 fill valve will give you much over 4-5 gpm, barely enough to power flush a 3/4 circuit, much less a bunch of radiant loops all at once. Look for a high flow pump possible an old pool pump for flow and pressure to blast that run out.

Loop by loop works, but can take many many hours to flush an entire job. Richard "heatmeister" tells me he has flush out 55 gallon barrels of sludge from those non or semi barrier tube systems, and spent multiple days doing it. It is an expensive mess that we should be able to avoid, going forward.

Cleaners certainly help dissolve that sludge, but pressure and flow is needed to take out the trash.

GaryJ

Black sludge in Onyx radiant system is caused by oxygen in the system. A major design flaw of the older Onyx tubing is the fact that the rubber stretches and the aluminum O2 barrier does not. If the friction of pulling the tube through the framing is high enough then the tubing stretches and the aluminum rips. So depending on who drilled the system and if the installer was a bull and jammer the O2 barrier could be shredded. It seems to me the new Onyx has a different O2 barrier. A friend of mine is a boiler rep and we were discussing this one day and he said it makes since as the only heat exchangers he has ever had to warranty were on Onyx systems. My question is a friend asked me to look at a house he was thinking about buying. Onyx staple up, 18 years old, 11 zones and not one exposed manifold. Cast iron boilers with stack dampers. All 11 taco mixing valves have black crud leaking at the shaft seals. Leaking pressure relief valve with 15 lb pressure at 170 boiler temp. Cracked the boiler drain on the boiler and the water was clear. I smelled chemicals and old antifreeze. I am leery of the buried manifolds with a rubber to copper connection. A lot of the first floor is slab on grade and I think that PEX was used for the slabs as I found one manifold with PEX on it. gain I am worried about the buried manifolds with a rubber to copper connection. Any thoughts?

mattmia2

seems like the thing to do would be to put in a hx and use components designed for open systems on the radiant side of the hx