no return

Unknown

I've been asked to fix a poorly done replacement boiler installation that has a really impressive hammer. The attached cell phone photo doesn't show how sloppy the installation is. The system is what I believe is a one pipe counterflow gravity return. The two mains pitch up from the boiler and there is no separate return. The boiler is a W/M SGO. The piping is immediately reduced to 2" at the boiler goes vertical about a foot, turns horizontal for a foot, goes vertical again and then turns horizontal connecting into the branch of a tee. The top of the tee goes up to the mains and the bottom finds its way back down to the return tapping on the boiler. It didn't hammer with the old boiler. While it's certainly not the way I would have piped it I can sort of see what the installer was thinking. He piped the supply from the new boiler to the old supply and equalizing line to the return. It's just a new boiler. Does anybody have any thoughts on this? By the way, the pressure limit is turned all the way down and the water is clean. I plan to repipe it with a full size header.

Jamie Hall

Eek

Do repipe the boiler, please... find the manufacturer's manual, regard that as an absolute minimum bare bones job, and go from there.  I'm not surprised it's hammering.

Unknown

Counterflow System

Hi Bill-  I guess I don't have to say you need to use the a full port (2 1/2") exit riser coming out of the boiler. Depending on which model it is, I'd also consider using the second boiler steam port if its available. As you already know copper is a "NO-NO" on the steam piping.  In your photo I can't see the steam mains so don't know what's feasible there.



The concept of the mains being joined and having the combined volume of the return condensate being dumped into the upcoming steam, I would think would really cause wet steam problems.

I've attached a photo of a excellant counterflow system done by Steve Gronski which might help serve as a guide for you. The more you study it, the more you appreciate the thought that went into it.

Note:

1. The high header and equalizer similar to what you would have on a good parallel system,

2. The individual drip lines on each main returning the condensate directly to the wet return and keeping it out of the risers coming up from the header to the mains.

3. The steam risers coming off the header at a 45 degree angle so condensate in the pipe flows back rather than drops into the steam steam.

4. Note also the fresh water line is setup so that it can blow down the wet return.

Counterflow systems have their limitations though setup properly like this one, they should work very satisfactorily.

- Rod

Unknown

counterflow system

Drip lines! I've successfully replaced boilers on this type system before and now that I think about it they all had drip lines.



I always make the header the same size as the tapping in the boiler unless the manufacturer says otherwise. I also always put the water feed into the wet return.



I know this is controversial but I have to disagree with you on never using copper on a steam system. Twenty years ago I would have agreed with you. Every system that I saw that was done with copper didn't work right. Then I ran into a job that was many years old that had been done in copper and questioned the customer about it. It had worked perfectly ever since he owned the house. It occurred to me that the systems I'd seen done in copper probably wouldn't have worked right if they were done in steel. I've since done many of them in copper and they all look infinitely better than the one in the picture I attached. I follow the manufacturers piping diagram and provide for expansion (don't scrimp on the elbows). I've had plenty of opportunities to check up on these systems when doing  other work and they all look and perform as expected.

Unknown

Do it right!

Whether it is wise to use copper for steam pipes or not probably depends where you are located. If you have starving lawyers in your area you would do well to stay away from copper as it isn't the accepted industry standard for steam pipes and you'd lose in court big time.

The steam pipes in my house just celebrated their 100th birthday last year. That's 100 years of pipes & fittings expanding and contracting. Do you really think a sweat joint will last that long?

Unknown

I'm not trying to convert you.......

..........but the temperatures and pressures of a residential low pressure steam system are well within acceptable limits:



http://www.copper.org/applications/plumbing/techcorner/cu_tube_steam_systems.html



Anyway, thanks for refreshing my memory on the drip lines.

Unknown

Copper

 I understand what your saying though after seeing many pictures sent to this site of copper piping that was supposedly done by pros, I'd question whether it is possible to regularly achieve the degree of workmanship necessary to pipe a steam system in copper that would stand up over time.  The other obstacle you have is, that even if you have perfect brazed joints, when  the system  was inspected somewhere down the line by a person familiar with steam (like an insurance or house inspector) they would see the copper and immediately condemn the system.  We had a discussion about Hartford Loops a while back. While it was acknowledged that with the modern LWCOs, it is questionable whether one really needs a Hartford Loop anymore, the consensus was woe betide anyone who got involved in a lawsuit and hadn't put a Hartford Loop on the steam system they installed.  Like using black pipe, the Hartford Loop has become a fixture in a steam system. 

- Rod

Unknown

insurance inspector

Funny you should mention insurance inspector. I just did a job replacing a small commercial boiler. The insurance company sent out an independent boiler inspector. He looked it over and didn't have a problem with the copper. He did have a problem with telling the insurance company that the old boiler cracked. It was a Burnham V series and he know about them.



Here are a couple of pictures of the installation. I was worried about the distance between the boiler and the main. I bid on the original installation 15 years ago and didn't get the job and I remember the boiler was in a pit that was filled in for the new boiler and the guy who put it in had to come back to do some repiping to get rid of the banging. My installation was quiet.

Mark Eatherton

Bill, do you understand the function of a swing joint?

How about the mechanics of dissimilar metal corrosion?



Let's start there. It takes two dissimilar metals, i.e. copper and steel, connected together and exposed to an aqueous (oxygenated) solution. In that case, the lesser of the two noble metals (steel) is guaranteed to fail in relatively short order. You have the perfect galvanic corrosion principles shown in those pictures.



Now, about swing joints. In the single headered picture you show, probably not a big deal. But in situations where you have two steam boiler riser ports connected together with a header, most manufacturers I've read REQUIRE the use of screwed pipe in such a configuration that pipe expansion is taken up by the swing joints and not directed to the castings of the boiler.



Even if you duplicated the drawings the factory shows for swing joint using copper pipe, soldered joints have virtually NO give to them, and will impart stress to the castings of the boiler, acting like a pry bar to pry the sections apart.



Additionally, although it may appear that the copper and solder can withstand the temperatures and pressures you might see in a typical residential system, on every steam system I've taken apart with soldered joints, the joint literally fell apart in my hand, almost like there was no solder in them at all.



Now, it is your company, and you can do your jobs however you want, and very few inspectors is going to call you on the carpet, because most of them have no freakin' idea what it is that they are looking at anyway, and are only interested in seeing low water cut offs, fuel cut offs and Hartford loops, but I guarantee you, you will catch a lot of flack from the respected steam professionals frequenting this site.



Almost every one of us has had to undo copper systems that literally tore the boiler or piping systems apart.



You can use it in condensate returns, but you MUST isolate the connections between the copper and the steel with brass, or the steel will die.



Just sayin'... You can do it right, or you can do it again, and again, and agin...



ME

Larry_52

galvanic

Hey Mark,



The effect of galvanic corrosion in a steam line is not as severe as you might think.  Between the cast iron and the copper it is a low potential of cathodic reduction.  "Good" steam has relatively no current carrying potential.   Now I am not condoning a copper header but allowing for the expansion of copper it should last.  Funny thing is copper today ain't cheap, steel would prove the cost effective way & preferred method.

Charlie from wmass

Well Larry how about the condensate?

Every pipe that carries Steam also has condensate in it at some point in the firing cycle? Copper is used not to save on material but to save on tools and labor. Cutting and threading 2-4 inch pipe is not a quick thing compared to soldering copper tubing. Remember what is being used is copper tubing not copper pipe. Pipe has a thick wall and is threaded. I was at a typical copper job today. It bangs and the pressuretrol was set at 3 psi cut in and 3 psi differential. The boiler was installed by the oil company they had at the time. The dry returns were tied together 5 feet above the basement floor and the 40 year old 1/4" straight pattern vent is all they have for main line venting. And they have no money to repair the installation now having had to pay for the original boiler and its sub standard piping job.

Unknown

Mark, have you ever tried to unscrew a swing......

......joint after it's been installed for a few years? A swing joint is essential for piping a boiler in steel but I don't think it's doing a lot of swinging after that. A "swing joint" is also essential for piping a boiler in copper because the 90 degree turns allow for expansion without stressing the boiler.



I've attached a photo for your amusement. The steam piping is not mine. We added the heat exchanger and radiant zone. However, the steam piping does appear to be as old as the boiler. Neither the boiler nor the piping show any signs of leaking or corrosion.

Charlie from wmass

sewer

Yep sewer fittings Thats a real quality job. Please note sarcasm. Hacks will always be there. Some times they get lucky, the rest waste peoples money or kill people.

Jamie Hall

At the risk...

of calling down the wrath of the gods whom I respect mightily...  seems to me that one can use copper for steam successfully.  Provided, however, that one pipes rather differently.  The same layout which will work beautifully for steam in threaded iron, and which is simple (and, to mollify the gods somewhat, preferable) simply isn't right for copper.



In both arrangements one needs to have provision for expansion -- and for differential expansion. 



With threaded iron, we have three major advantages: first, in most cases both the boiler and the piping are very similar metal, with much the same expansion rates.  Thus the differential expansion (which comes from the boiler temperature going up before the header temperature, etc.) is very small.  Second, with threaded pipe, even after years of sitting there, there is give in twisting in the joints.  Not very much, perhaps, but quite enough, given the piping layouts usually used (those swing joint arrangements!).  Third, the swing joints do allow for differential expansion and do not stress anything.



With copper, the situation is rather different.  First, the coefficient of expansion for copper is very much greater than that for iron.  Thus there is a lot of differential expansion to be allowed for.  Second, soldered joints have no provision for twisting (and pipe is very very stiff if twisting).  Therefore, the usual piping arrangements we use wind up with no provision for expansion, and something gets broken.



If one uses copper, then, it is necessary to figure out a way to allow for expansion.  Of course, if there is only one riser from the boiler -- a smaller installation -- there isn't a problem with the boiler, and there isn't likely to be a problem overall (except for expansion noises everywhere in the system, but that's another matter entirely; a noise may be a nuisance, but it doesn't break anything).  But if there are two risers or more... ah.  One approach which works is to count on the threaded joints of the risers to the boiler to allow twisting at that connection, and to put a threaded type union in the other vertical pipe (thinking that one goes up, over, and up or down to the header -- it's that second vertical up or down I'm talking about) which will allow twisting in that length of pipe.  Presto.  Provision for expansion.  Alternatively, if the pipes are long in relation to their diameter (the 2 feet often found isn't enough for anything bigger than say an inch) the bending in the pipes will do it (copper is significantly more flexible than iron that way).



But the problem is expansion, and if one can solve that, one can use copper.

Mark Eatherton

Sawzall surgery...

Generally speaking, I use a sawzall to expedite deconstruction of most systems, so no, never tried to take one apart.



The picture you have displayed (other than improper use of DWV fittings) has swing joint provisions.



The next time you get a chance, cut apart a copper to steel dissimilar metal connection and pay particular attention to where the two metals meet, and what is happening to the steel. It looks like some sort of cancer or something. Definite corrosion.



As has been pointed out by other posters, there are more disadvantages to using copper than the only one advantage, that being labor savings.



So, it's a free world, and you can pipe your systems the way you want to, but the Dead Men are rolling over in their graves...



Proceed with caution.



ME

Unknown

corrosion and other things

I usually try to unscrew the fittings in the hopes that one day one will unscrew. Most of the time it's, cut, slice and hammer out with a chisel.



I have cut apart other peoples copper and have never seen the corrosion you mention. I understand why corrosion could occur. But if it was a big problem wouldn't we see it to some extent in forced hot water? The temperatures are lower and there should be little or no air inside the pipe but there's plenty of air outside.

Mark Eatherton

It's all about oxygen...

On a steam system that is set up correctly, every time the boiler shuts down, it sucks in oxygen.



In a true closed loop hot water system, the free oxygen is removed in the process of heating the water and in those systems with a conventional compression tank, a protective patina is set on the steel to avoid additional oxidation.



I realize you didn't pipe the first boiler picture you showed, but there are two dissimilar metal mixes (copper directly to steel) in that picture.



Copper to cast iron is not as bad as copper to steel. But they are both bad in the presence of oxygenated water.



ME

Steamhead

You'll change your tune

if you ever see what happens when a soldered joint on a steam pipe breaks. 



One gentleman I have great respect for has actually seen this happen. He tells me that first, you can't see anything as the boiler room instantly fills with steam, so it's difficult to find the exit. Then you have 212° rain as the steam condenses and drips off the ceiling. Finally, the escaping steam displaces the oxygen in the room, making it difficult to breathe.



Not a pretty picture. It's a shame not all boiler makers tell you not to use copper for steam pipes. They could incur some liability for not doing so.



The insurance inspector we usually deal with is a retired Navy engineer. I doubt he'd approve copper steam pipes.

Unknown

Let's talk numbers

Take a look at this:



http://www.copper.org/applications/plumbing/techref/cth/cth_3design_gencon.html



Let's assume a residential boiler with one supply tapping and use some round numbers. The piping goes up from the boiler 2 feet, horizontal 4 feet and down to the return 4 feet. That's a developed length of 10 feet. With a 200 degree temperature rise the entire length of pipe is going to expand .223 inches ( Piped in steel it would expand .178 inches.). That's spread out over the entire length of pipe and the way I pipe them there will be 3 to 4 elbows. You'll also notice on that page that they say that for long lengths of pipe, and this isn't even close to that,  "... stresses, buckles or bends are prevented by the use of expansion

joints or by installing offsets, "U" bends, coil loops or similar

arrangements in the tube assembly.".  I realize that site is published by the Copper Development Association and their job is to sell copper but facts are facts. Following any manufacturers piping diagram you're going to have offsets and/or U bends. It's simple for a single supply system but you have to be a careful when there are two supplies.



As a side note, I've seen a picture of a two supply boiler piped in steel that had the sections pushed apart. As I recall there were two vertical supplies with elbows looking at each other and a tee and union in the horizontal piece. I have no idea how the guy got it together. I assume expansion pushed the sections apart. It wouldn't have worked in copper either. Wrong is wrong.