Flushing Wet Returns?

Steamhead (in transit)

so I can't speak to it. But, I've found flushing the boiler and wet returns with a hose (while the boiler is COLD) works about as well as anything. Plus, you don't have to worry about getting all the chemical out of the system if you aren't using chemicals in the first place.

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ed_47

Flushing Wet Steam Returns?

In older residential steam systems I understand there are benefits to flushing out the crud and water in the wet return piping? Does introducing freshwater create more problems? I have access to dionized water, would that be a better subsitute if I flush the old out? Thanks to all for your advice.

Steamhead (in transit)

You want to get rid of the crud

which all gets flushed out. You don't want that crud getting in the boiler!

If you run the system immediately whren you refill it, and wait until the returns get hot all the way back to the boiler, it will drive the oxygen out of the water and make it less corrosive.

"Steamhead"

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Ken_40

DI water?

because of its affinity to free ions, it is extremely corrosive. I'd stick with plain-jane tap water.

The notion that the returns are filled with crud, may not be the case. The amount of crud is driectly relkated to the "tightness" of your system. The components that control that are the vents (both main and rad) and the packing nuts on each radiator stop.

If they're all good, you may have to add water once a month in the dead of winter. If they're "leaking," you'll have to add water once a week, or more (in the dead of winter).

Any pipe leaks must be attended to immediately.

How would you characterize your system? "Tight," or something less.

If tight, the surmised crud will be virtually non-existent. This is not to say the returns may be diminished in I.D., but that kind of stuff ain't gona be flushed out anyhow! That's the age of the system acting normal...

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Steamhead (in transit)

But the only way to tell for sure

is by flushing the returns!

Of course, if you flush and the water runs clear, they're clean and you can stop right there.

But I've never seen a wet return that didn't have SOME crud in it.

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Big Ed

It Could

.....open up a bag of worm .I agree clean returns are important. But if they leak after you flush them out ,where would the blame lay ?I would recommend replacement first if lines are old. They all leak ,just a matter of time.

Drew_2

Deionized Water

Ken
I believe you are mistaking "Ultra Pure" water with standard deionized water. I've attached a couple of documents that explain this.

Rik

cleaning fluid

I'm also planning to have my steam system cleaned this summer for the first time (at least since I've lived there, 2 years.) The technician mentioned he would be using "steam clean"... some kind of green cleanser I gathered. Just wondering about the toxicity of this. He's planning to dump the outflow into our sump pits. We're planning to extend our sump output so it wont go right into our yard/garden, but I am interested to know just how nasty this stuff might be.

Ken_40

Be very careful!

There are some steam-boiler water "clarifiers" that will make the water in the gage glass stunningly clean/clear.

They are in fact flocking agents. Flocking agents are chemicals that bind floating particulates, rust, oils, unknown contaminates etc. together and a gel forms in the boiler water, over time they capture all the "contaminants" and become denser than the water they are suspended in, and slowly drop to the boiler "floor" as a gelatin mass of the agent, and the stuff it "captured."

This produces something bad. Bad in that the flocking agent (typically a lye-based compound) will dissapate over time, concentrating the trapped solids and the gel that with heat, will become chemically afixed to the steel or iron base of the boiler block. This forms (probably in a week or two) an "eggshell film" on the boiler bottom.

If there was only trace amounts of contaminates in the water, the need to "clean" in this manner is rarely done. The result? Boilers that have lots of particulate contamination will tend to be chosen for this "treatment."

With firing, the gelatinous particulate becomes the eggshell coating similar to porcelean on an iron tub or slop sink.

Here comes the problem: The expansion rate of the porcelean-like "coating" the cleaner created is quite different than plane old cast iron alone. This differential is so significant, the warranty of the block is voided when this is done. The tension is so great between the porcelean-like eggshell and the iron it is almost molecularly affixed to, that the iron can crack!

Ideally, there should only be three things in your boiler. The boiler block itself, air, and either neutral or alkaline water.

Other than certain pH increasers: cleaners, additives and flocking agents should be avoided. Flockulants, unless designed to be totally flushed away and that part being absolutely perfomed as stated on directions saying so - can damage a boiler block - and void the warranty!

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