Steam Returns

bob young

yes, there is a reason. plastic is not supposed to be used for steam systems. it is cheaper but not correct. use pipe-----steel, ex. heavy or L or K copper or t.p. or brass pipe. not plastic.

152NP

Steam Returns

Is there any reason why SCH40 PVC pipe cannot be used for the portion of a two pipe steam system return line that is between the F & T traps and the boiler feed tank?

ttekushan_3

all I can picture

is all that wilted, outgassing PVC with 200 degree condensate going through it- and the finishing touch delivered by a steam trap failure. It'll look like a clothes line!

-Terry

P.S. I plan to spec all PVC for my next steam system as soon as I perfect the Styrofoam boiler. It'll be so much easier to work with. ;-)

152NP

All right, I guess I deserve a little ribbing for my seemingly silly question, but I do have a reasonable explanation why I would ask such a thing.

My deteriorated return lines have been springing leaks almost weekly the past few months. Being that it is a large building full of business tenants, a quick fix until a more convenient time when the system can be shut down for proper repair is an attractive idea.

I have had two different mechanical contractors make the comment that they did not know of any reason why plastic and some ferncos wouldn’t hold for a while.

Ultimately, I figure, it is dependent on the water temperature. SCH 40 is rated for 140F. I know condensate could be at 200f +, but the sections that are leaking are only warm to the touch.

Maybe my misunderstanding is the assumption that they were talking about PVC when they said “plastic”. I am sure there are other plastics that have higher temp ratings.

To me, some kind of plastic would make good sense for buried returns as it would be corrosion resistant.

nicholas bonham-carter

leaking returns

what about rigid, or flexible copper tubing? just make sure it is well under the waterline.--nbc

Jamie Hall

There are...

some 'plastic' pipes rated up to 180 or so, maybe even higher. And you are quite right; for a wet return -- always solidly below the water line -- a good high-temp plastic is usable, and might be particularly good for a buried line (and I have some I might try if they ever fail).

That said, your worst case scenario is a failed trap, which will get you live steam into your dry returns. You might get lucky and have it just sag something fierce. You might get unlucky, and have it pull apart, just like taffy, at 2:00 AM and have live steam all over the place. I myself wouldn't particularly be happy about the latter...

clammy

steel pipe

Chris instead of wasting your time with temp fixes why not just have the returns re placed once with steel pipe and your done instead of having liability issues and possible insurance promblem should things go bad,in the long and short run of things a good plumber/heating guy with a decent crew should be able to replace those returns depending on location in better time then a quick fix and then having to return to doit all again.personally i would re do it with steel pipe and install some croos tee 's and valves so that future cleaning and flushing of the returns does not become a bigger job then it should be and remenber just how long those original steel returns lasted with out to much maintance while some would recommend copper i believe it 's only due to the fact that it quicker install andrequires lesser skill then doing it in steel and then lets not forget that the price of copper is not as cheap as it used to be and if there tenants in this areas just remenber they may be exposed to a ruff enviroment that steel would probalby handle alot better then copper but i am bias towards steel feeling that doing steel pipe requires a skill which is on the outs in alot ascepts in both plumbing and heating fields ,gas tite .in closing just remenber that it's always cheaper to do it once correctly is much better then doing it twice and then still have issue that will cost more to correct.hope this helped peace and good luckclammy

ttekushan_3

Wasn't making fun, Chris-

I was dead serious about styrofoam boilers while the pain in my shoulders persisted from moving cast iron boiler sections!

Its just that you had mentioned steam traps, which regularly get hot. Fernco fittings and plastic at a steam trap is something I've actually seen as a quick fix. Naturally, the temporary fix was 3 years old and had 2x4's holding everything up as the ferncos over plastic pipe would loosen up very regularly. When I got there everything was so deformed from the trap outlet temps that it would no longer seal.

So I'm not going to advise you to use plastic even where temps are lower, since its not code and nothing more than a quick fix. If you are sure the quick fix is temporary I can only say that no one here has affirmed the idea but use your own judgement. No gates of hell will open, and I doubt a plague of locusts will invade if you do it. But if they do-- You heard it here first!

-Terry

152NP

Thanks everyone.

I thank everyone for taking the time to offer their input on this matter. You have convinced me that “fix it once, and fix it right” makes the most economic and functional reliability sense. So, steel it is! The current below the water line piping is 60 years old, and the dry returns are 100. All the recent problems, I am convinced, are the result of the building’s previous owner neglecting to fix a water feed that ran continuously for a few years due to a failed water pressure regulator. I don’t have high hopes for the internal condition of the boiler either, but that is a whole other topic.

Thanks again.

Unknown

I was under the impression

that steam boilers hit 212 degrees and that's it .

Found out recently the hard way that it can go much higher . We installed a steamer with an internal coil for a zone of heat . Temp gauge on the coil read 240 degrees while steaming . Typically there's a temp difference of up to 20 degrees from boiler to coil , so we're talking mucho hot water in the steamer . Next time the coil will get a bypass . And next steamer I'm going to throw in a used temp gauge just to see how high the temp really gets . Temporarily of course .

Thing is - when the pressure starts to rise and the boiler water backs out of the boiler , you're gonna have superhot temps in the returns .

I'm not sure how well PVC can handle those temps . I'm shocked though that I haven't come across a PVC return yet