which way should main steam pipe from boiler pitch?

borowiec

I realize this is probably a really dumb question, but I can't find a clear answer either on this site or in "We've Got Steam Heat."
We just had a new boiler installed for our 2-pipe system and we are experiencing major hammering shortly after the boiler fires up. It's pretty clear that the hammering is happening where the horizontal supply pipes in the basement meet the risers: you can see and feel them moving, and see paint and plaster flaking off from the vibration. We rarely had any hammering with the old boiler, just sometimes on really cold days. The installer says it can't be anything they did, as they put in exactly the same model boiler as before and nothing changed.
However, I see that they raised the supply main above the header in relation to where it was before: they had to cut away to insulation to install an new strap and they cut the original pipe straps. Could that be the problem? If steam condenses into water in the supply main, is it supposed to flow backward to the boiler, against the direction that the steam is moving, or should it flow in the same direction as the steam and eventually make its way into the return pipes?

lchmb

how about some pictures? look in the manual, there is a piping diagram in there..does it match?

EBEBRATT-Ed

Normally the pitch in the mains is high at the boiler and the pipes pitch downhill. Some older systems are counter flow and the pipes pitch back toward the boiler.

Either way the thing to remember is if you were a drop of water in that pipe is there a way for you to get back to the boiler by gravity.

Pictures will tell the story. Obviously it is something they did

coelcanth

maybe if they cut the original straps on the main, they left it unsupported somewhere and introduced a sag..
that could've created a spot for water to collect

nicholas bonham-carter

The installer said it couldn’t be anything he did, so who else is to blame? Maybe he will say it’s you!
They put in the same model of boiler as before, but was it the right size, according to the EDR, and was it piped following the manufacturer’s installation instructions? I would not pay until it’s right, as it should be.—NBC

Jamie Hall

Are there any drips from the ends of the steam mains where they turn up into the risers? If not, it was intended to be a counterflow system -- which needs a good deal of pitch. If they raised the end of the steam main at the boiler, they reduced that pitch (or even reversed it) and it is, indeed, going to hammer like crazy. That would be my bet from what you've written.

Might check the pressure they set the new boiler at, too, while you're at it -- if they did that, who knows what else they messed up?

borowiec

Thanks to all for your responses!

Ichmb, I will post pictures shortly. I will check the manual to see if the piping diagram matches what I have, but they did not change any of the near-boiler piping, except that the system take-off had to be shortened as they placed the boiler on cinder blocks, so it's higher than the previous one.

Ebebratt, it looks like there is a return on the supply main, about half way across the basement, and that the main pitches down toward that return, then upward from it to the riser is hammering the most. Again, I will post pictures.

Coelcanth, while they did cut some straps, the effect was to raise the main at the boiler, and then everything continues to pitch downward from the boiler.

Nicholas, they had also installed the previous boiler fifteen years ago, so they claimed that it was the correct size, then as now. I think the size was correct, the old one worked fine until is rusted out.

Jamie, I don't believe there are drips where the mains turn into the risers but will double-check. The pressure is set at 5psi which, according my wife who checked it (she's the engineer in the family) is as low as it will go. Again, will double-check that.

JUGHNE

Raising the boiler on cinder blocks also raised the water line.
If you have any return piping dropping down anywhere in the basement, that does not go below that new water line, can cause a multitude of problems.

One should never argue with the wife, but any control can go down to 2 PSI or lower.....show her this posting....I will be the bad guy.

Jamie Hall

Or if you don't want @JUGHNE to be the bad guy, I'll take the rap. Turn that pressuretrol down. I you're not sure how, post a photo and we can tell you what to twiddle and how far.

I'm a little concerned about that arrangement with the main sloping to a drip part way along, and then going up from there. That going up end is counterflow and needs good pitch.

Perhaps more to the point, when they raised the boiler and its water line, they also raised the elevation that the water will rise to in that midpoint drip. And I wonder if that drip is draining properly. Early on in the steam cycle the mains are condensing like mad -- so lots of water -- and the pressure in the mains will be significantly less than that in the boiler. Can you, using an accurate level, measure the elevation difference between where that drip comes in to the main and the water level in the boiler? May be a bit of a trick if it's half way across the basement, but you could rig a water level level from some hose...

borowiec

Here are two photos of the boiler near-piping, you can see where the supply main insulation was stripped away so that a new pipe strap could be attached:





This is what I believe is the return off the supply main, about two thirds of the way across the basement from the boiler:



This is the far end of the main, where the hammering is hardest (to the point where plaster now falls off the ceiling). There are no drips installed. Note that the ceiling-height radiator is not unsupported, as it appears: despite the broken strap, there is a 4x4 post holding it up from below.



And here is a branch off the main, where there is a riser. There is hammering here too, though not as severely as at location of photo above.

JUGHNE

Need to see the pipes on or at the floor in the entire basement.
Around the lower part of the boiler also.
Back up for pictures please.

nicholas bonham-carter

Two pipe systems run best in the ounces range, and although pressuretrols can be calibrated, and coaxed into the 1.5 psi range, they are really too inaccurate for any lower pressures.
Look for any negative slopes, creating a low spot, trapping water.
Is there an equalizer on the near boiler piping? It looks like the risers are on both sides of the main take off, which can blow a lot of water up into the pipes, with subsequent water hammer.
Why did the old boiler die so young? I would have expected 30 plus years out of it.—NBC

KC_Jones

borowiec said:

Nicholas, they had also installed the previous boiler fifteen years ago, so they claimed that it was the correct size, then as now. I think the size was correct, the old one worked fine until is rusted out.

I would also question why you had such a short life on the old boiler. The issue that caused it to fail prematurely could happen on this new boiler.

What is the water usage like?
Was the new boiler skimmed?
Has the contractor offered any solutions to the problem?

The beginning of the main should be the highest point (circled in red), and everything slopes down from there, and must be straight. So a level and string line are your friend here if you want to check everything.

Steam shouldn't bang, the contractor should know this and should fix it. They should have asked you about this before the install to address your issues.

I will reiterate what was mentioned above about sizing, most boilers we see on here are over sized. If you would like to verify this let us know. The calculations to check it are pretty straightforward. If the boiler is too big, running it effectively at very low pressure becomes difficult without adding extra (non standard) controls.

Jamie Hall

Yeah, normally that would be the highest point -- but he has at least two risers right at the end of a runout (second picture in the group above). That pipe, whether it's though of as a main or a runout, has got to have a good slope back to the nearest drip. And I'll be that's where the problems is...

JUGHNE

I believe they shortened the new lower vertical pipe riser too much and lost the slope towards the end of the main.

Looking at the end of the main across the basement, that drop pipe......does it go almost to the floor and then head to the boiler return?
Also at the end with the drop pipe there is a pipe coming of the top of the main, does that go thru the wall to another room feeding more radiators or just up to one radiator.

Does anyone here know if they make "extension filler flanges" that could raise that main up without adding pipe length?

If not then, just remember my idea....intellectual property. BTW

JUGHNE

Jamie, if that top take off at the end is a main extension, it looks counterflow and the end would be a real collection pool. IMO

Jamie Hall

JUGHNE said:

Jamie, if that top take off at the end is a main extension, it looks counterflow and the end would be a real collection pool. IMO

My thought exactly. Bang bang bang...

JUGHNE

And then by raising the boiler water level is that return below the water level anymore.....pictures are anticipated....

borowiec

All, thanks again, I will take and post more photos and try to address all your questions tomorrow morning. Your responses are much appreciated!

EBEBRATT-Ed

I think the header is correctly piped but is it the right size? I think I see the equalizer coming off the end and changing over to copper.

raising the boiler may have created some issues.

Need more pictures from farther back.

measure to see if the header is 24" above the middle of the gage glass

borowiec

NBC: Plumber says the pressure is 1/2lb; Pressuretrol shows all the way down to ½ on scale, differential set at 1. There are no obvious low points and remember that there was no hammering prior to installation of new boiler. The only change in the piping that I can tell is that the supply main is higher at the boiler than it was before. The risers are not on either side of the main takeoff, the new photos should make that clear.

The old boiler died because several of the sections rusted out due to that room flooding during heavy rains. It no longer floods, I finally was able to remedy that.

KC Jones: water usage has been 11 gallons since installation of the new boiler, which was completed on November 8.

I have texted the installer asking of the new boiler was skimmed, will post his reply.

So far the contractor says that, since they used all the same piping and it’s the same model boiler, the hammering can’t be the result of anything they did. His employee says the solution to the hammering is to replace all the radiator valves (!).

For sizing, I would be happy to have you check, please let me know what info you need from me.

Jughne: If anything raising the end of the main at the boiler increased the slope away from the boiler. The drop pipe (location E) goes almost to the floor, then along the outside of the building and joins with the other return behind the boiler, see new photo. The other pipe above the drop pipe goes to a radiator in a bathroom on the second floor, it seems it’s just that one. The main itself continues through the wall into the darkroom (see photos) where it branches in two places to feed a total of six radiators on higher floors, as well as the ceiling-height radiator in the darkroom.

The return is definitely below the water line and there is more or less the right distance between the water line and the Close nipple, 2” per installation diagram.


Ebebratt: As best I can tell by looking at the installation diagram, the boiler is correctly piped. The header is 29” above the center of the gauge glass.

Here is a diagram of the heating pipes that run through the basement, mainly at ceiling level. The key should be self-explanatory, but I forgot to label the thin red arrows: they point in the direction of downward pitch, so you can see that the main pitches down to the drop pipe return at location E, then it rises as it heads to location F, which is where the most violent hammering occurs.



Some new photos of the boiler:





Photos of pipes, see plan for locations. Location A



Location B:



Location C



Location D



Location E



Location F

borowiec

Two other things: Yesterday I spent five hours in the room where the hammering is worst (location F) and the heat came on many times, but there was no hammering at all except right at the end. Today there has been no hammering until right now, as I write this, heavy hammering at location F as well as the other spots marked H on my plan. Note that in between the hammering you can hear water sloshing and gurgling in the main at location E.

Secondly, is it normal for the boiler to cycle on and off even though the thermostat shows that the set temperature hasn't been reached? This morning is would run for about five minutes, then turn of for a few, then fire up again.

KC_Jones

The on and off is most likely cycling on pressure, which could indicate an over sized boiler, lack of venting, surging due to it needing skimming, or all of the above.

11 gallons since install, that a couple years worth of water usage, you have a bad leak or a bunch of tiny leaks amount to a major water loss. This is probably what killed the old boiler.

This is no joke, it's appalling that your contractor is not talking about this. I am guessing they like replacing boilers because they make good money on the work.

Valves are not fixing water hammer, wow, just wow.

Can you take a wider picture of the hanging radiator so we can see both ends and how it's piped, also which was is that radiator sloped? Is there a similar radiator at the other hammer location? I don't think you posted a picture of the other location that is hammering, could you please post a picture of that?

For sizing measure the depth and height of each radiator then compare that to the style and size on a sizing chart (see link), that will give you the EDR per section. Then multiply that by the number of sections for each rad and you get total EDR of that rad, add up all the rads in the house and you are done. If you post dimensions and pictures of each rad I'd be happy to run the numbers for you, actually probably better to PM me if you want that assistance. As an aside, your contractor should have done this already, but I am guessing they did not.

borowiec

KC,

Here is the plumber's response to my text asking if they skimmed the new boiler: "Yes that would have nothing to do hammering. Armin told me that it was hammering on the basement pipe in the dark room and my suggestion would be turn off that radiator. Replacing a boiler would have nothing to do with anything that’s going on up in the house. It’s the exact same boiler exact same piping. No changes. Probably going to have to try to isolate the noise to a particular spot. If it sounds like one radiator then shut off that radiator and see what happens there."

Armin (his installer) never went into the darkroom, he's just repeating what my wife told him, that there was hammering in that room. However, it's obvious that the hammering is in the main, which you can see shaking, not in the radiator, which doesn't vibrate at all.

Here are two photos of that ceiling-height radiator. It's pitched away from the valve, i.e. downward to the right in the photo, toward the return end. However, it's a very slight pitch, it probably should be increased—I need to try to get some shims on top of the post that is supporting the left end.

There aren't any similar radiators at the other two hammer locations. At D there is a radiator in the room above, while the third H is where pipes rise up to a radiator on the second floor only. I can't easily photograph that without removing a panel in the ceiling.

borowiec

I need to get to work, will not be able to post until tomorrow morning. Thanks to all for your help!

KC_Jones

I know pictures can distort sometimes, so this might be meaningless, but will present anyway. I see sag in that pipe, I drew a straight line over the picture for reference. Again could be lens distortion, but worth checking with a string line.

Also I would expect the pipe and radiator to be parallel to one another since both should be draining condensate in the same direction. The don't look parallel in that picture, but could be camera angle.

Question about skimming, skimming takes hours of standing around with water trickling out of boiler. If someone was home they would know if it was skimmed because of how long it takes. Just a little food for thought. I don't disagree with his assessment, but if they are doing this type of work they should be able to diagnose the problems, for a price. If the contract was for boiler replacement then they shouldn't do it for free. That said, they should have asked you about any existing problems, done a system analysis and made recommendations to you.

borowiec

About boiler size, I believe the contractor did do that calculation when he installed the previous boiler. However, I will measure the radiators tomorrow and post the result. Thanks again.

ethicalpaul

> Here is the plumber's response to my text asking if they skimmed the new boiler: "Yes that would have nothing to do hammering.”

This isn’t necessarily so, is it?

Jamie Hall

You should never hear water gurgling or sloshing in either a main or return. You are going to have to do some creative detective work and find out why that area is a low point, nd why it doesn't drain properly. Assume nothing!

neilc

look at that picture between E and F, the main and the other return coming into it,
then look at that small return line,
what says that small return line isn't clogged and holding back condensate, all the way up into that main and return ?
slosh, slosh,
were the returns flushed ?
do they flow?

neilc

the darkroom rad,
does it pitch to it's drain?

JUGHNE

I am suspicious of that return also.
First I thought the horizonal line of it was above the water line.
It is fairly close. Can't see the sight glass in relation to where it connects.

It is just an end of main drip, a little pipe work may have moved the sludge enough to cause slow return.
That would back up a lot of water in that corner connection.

borowiec

I have used string to check, there is no sag in the main pipe above the hanging radiator. That pipe has a significant downward pitch from left to right, but the radiator also has a slight pitch in the same direction (away from the valve end), though it could be increased. The photo is not level, which is why the pitch of the radiator isn't apparent.

At this stage, I'm not sure what calculating the needed boiler size would accomplish; it's not as if the plumber would switch it out if it's the wrong size.

The entire installation, including demolition and removal of the old boiler, took three days. Despite the plumber's assertion that the boiler was skimmed, it seems unlikely that they did that, given the time frame. We did not observe whether or not it was skimmed, as the installer was very unfriendly and made it clear that he wanted us out of the way, so we stayed clear.

The low point for the main where I hear water is what's shown in this photo:



The pipe indicated by the red arrow is the one that goes into the room with the hanging radiator, which is where the hammering is worst and where I hear water. Almost all of the steam piping throughout the basement pitches back to the return line seen in the photo, and the far ends of those pipes (main and extensions) are precisely where the hammering is taking place. I think Nelic and Jughne are right: that return in the photo above is inadequate for the volume of condensate that needs to flow into it. That could explain why the hammering, which was constant for the first week of the new boiler, has now died down and is much more intermittent: there was either some kind of obstruction in that return, or it just took a while for condensate that had built up to drain back to the boiler.

So the question is what to do now. I supposed I will have to pay the plumber to clean out that return, as that was not included in the contract for the boiler installation.

borowiec

I have another question: the return line show in the photo above (location E) runs around the outside wall of the basement and eventually reaches the boiler around the back. The arrow shows that return line's end (you can see a wider view of this in the second boiler photo above):



So the return is below the water line. However, it's about 3.5 inches lower in relation to the water line than it was on the old boiler, since the new boiler is raised on cinder blocks. Could that affect the ability of the condensate to flow back into the boiler?

In a related matter, the installation manual specifies that the water line should be 23 13/16 inches above the floor. However, due to the cinder blocks, it's actually about 27 inches above the floor.

borowiec

NBC: you say that the Pressuretrol is not the best control for a two-pipe system as the pressure can't be set low enough. What should have been installed instead of a Pressuretrol?

borowiec

Would that be a Vaporstat?

JUGHNE

The pipe is small because it is just a "drip" for condensate formed in steam mains.
If it handled actual condensate return from radiators is would have to be larger.
Also it has some length & fittings to it, adding to the chances of plugging.

IIWM, I would disconnect the end of it at the boiler and try to back flush it towards the drop end of the pipe. Hopefully a floor drain is near the boiler.
If very plugged I would replace it, but lower it down laying bricks on the floor and add valves with clean out hose ports on each end. The parts of it below the water line could be copper.

KC_Jones

Being below the water line that height doesn't matter, as long as it is indeed below the water line entirely.

IF the boiler was not properly skimmed, it can surge and throw excess water up into the mains, so from that perspective the work they did can be the cause of the hammering.

As far as pressure, if the boiler is over sized it and you try and keep pressure down (like it should be on 2 pipe) it may short cycle and fail to properly heat if it's extreme. For low pressure control a vaporstat is the device of choice. That being said, the pressure control is a safety device. Low pressure is really achieved by proper venting and boiler sizing, this is why I think proper sizing is absolutely critical.

JUGHNE said:

IIWM, I would disconnect the end of it at the boiler and try to back flush it towards the drop end of the pipe. Hopefully a floor drain is near the boiler.
If very plugged I would replace it, but lower it down laying bricks on the floor and add valves with clean out hose ports on each end. The parts of it below the water line could be copper.

Good idea, but I see a tremendous lack of service valves at the boiler which could make this difficult at best.

borowiec

Yes, that drip line is quite long and has many fittings. It would be difficult to replace it, as it's concealed in walls for part of its run. And there are no clean-out valves of any kind, the only way to flush it would be to open both ends.

The start of the run, i.e. location E, is 27" inches above the floor, which is also the height of the water line. So I guess it was good that the boiler was raised, otherwise a good deal of that drip line's piping would be above the water line.

The previous boiler, same exact model, had a mercury switch Vaporstat set to a few ounces and there was no cycling on and off.

As I said, if the boiler size is wrong, there won't be anything I will be able to do about it, but I will follow KC Jone's directions above and do that calculation.

KC_Jones

borowiec said:

The previous boiler, same exact model, had a mercury switch Vaporstat set to a few ounces and there was no cycling on and off.

They should have put that vaporstat back on, this could be adding to the problem. This part is on them and should be fixed IMHO, also they should have recognized this on their own.

Again, this IMHO only matters if the boiler is over sized and you are correct they probably won't do anything if they made that mistake.

I have a vaporstat on my system, and if I had it to do over again I wouldn't have wasted the money. The boiler is sized correctly and I never see over 3-4 ounces of pressure, so the vaporstat sits there doing nothing.

JUGHNE

I would start by just opening the end at the boiler and connecting a hose supplied by city pressure, say the water heater drain bib.

I would set up a hose tee/wye with a supply and drain hose.
Shoot a little water into the return, shut off supply, open drain hose and see what comes out.
If it looks like it might drain I would continue see-sawing water back and forth until it seemed to clear.

Just do not wash water up into the main until you are sure the water is draining well.

If that clears it then valves and drain connections should be installed for future flushes without the mess.

If that vaporstat is still on the riser be sure to save it and reuse.