dirt(?) in system

rhl

My entire system is copper/brass/pex. I have no black pipe anywhere. I have a caleffi dirtmag on the return. Radiators are Jaga low temp aluminum, or floor heat with pex.

After a few years of running the system, i notice that the caleffi flow valves are filled with brown water. Looks like dirt/metal.

I asked caleffi they said the only option is to replace the valves.

What can cause this? How do you fight against it?

Jamie Hall

Is the PEX oxygen barrier or PEX/Al/PEX? Is there any iron or steel in the boiler or pumps?

hot_rod

An expansion tank? Most are steel and will tint the water. If you start out with filtered water and add some hydronic inhibitor, the water tends to not turn brown or black.

Do you need or want to read the flow meters, most times they are used for initial balancing, then never looked at agin.
If so you would want to run a cleaner, flush, add low mineral filtered water and a squirt of conditioner.

One small steel nipple or any ferrous metal will eventually tint the water

Amtrol has a lined expansion tank, no exposed steel. Zilmet has stainless steel expansion tanks, if that is the metal in the system.

Rhomar and Fernox have a two aerosol kit designed exactly for that clean and inhibit procedure, does about 35gallons..

HomerJSmith

My considered opinion is that you have too high a flow in the copper pipes and you are eating away the inside of the copper pipes. I hope you prove me wrong.

ScottSecor

Unless I missed it, is the circulator pump iron?

rhl

Hi,

All pex is barrier pex or pex-al-pex.

Primary is a grundfos 3 speed (part of the boiler) — it’s a Weil McLain AB. 

secondary pumps are all alpha2s. — I’m realizing the alpha2 pumps may have some cast iron on them.

I’m traveling right now — I believe the expansion tank is an amtrol. 

hot_rod

Those cast iron circulator bodies tend to turn brown within days of installation. They even get rusty on the shelves in humid climates

rhl

Should i replace them? I realize its weird that an ECM pump is sold with a cast iron body at all.

hot_rod

The discolored water is not a big issue. Actually a thin layer of oxidation inside ferrous metal parts protects the metals from rusting or corroding more. Hydronic conditioner treatments include a "film provider" as one of the ingredients to coat and protect metals.

Think of anodized aluminum. They allow a small corrosion layer to be on the aluminum to shield it from harsh conditions. Same with Corten steel.

It would be almost impossible to have perfectly clear water in any system with steel in it. If every component was plastic, brass, stainless, aluminum, you might keep clean water.

You can get many circulators in stainless versions, about 3 times the price. More and more composites are also showing up for pump volutes. Problem with composites is they are oil products, so prices go up with petroleum prices. Sometimes they are less then stainless, other times they can be more.