Water Hammer and Tee's

pmchale

Greetings - any advice on some possible piping modifications I am considering would be most appreciated here. I have a one-pipe steam system, that previously had absolutely no venting (except on the radiators themselves). After reading Dan H's books, and from advice on a previuos post about my system, I (and contractor) added some Gorton vents to the main, actually two submains, where I was getting little heat. The system is not the best design (as I have been told on this form), but short of a lot of repiping, I am stuck with the main ending at a T, and then splitting to two sub mains, each with two radiators (one first floor and one second floor). These are the sub mains that we vented. Now, I get quite a bit of hammer, especially on start-up. It is pretty obvious that condensate water is now pooling. I am pretty certain that it is pooling at Tee's which split from the sub mains and feed the lower and upper radiators on each side....again, two sides are same, with a T off the sub main, supplying a first floor and second floor radiator. These Tee's are vertical coming off the sub main, and one even looks like it may tilt back toward the sub main (causing the condensate to pool and hammer??). I am considering repiping these Tee's coming off the sub mains, and replacing with separate 45's off the sub main instead, so that:
1. each radiator condensate feeds back down to the sub main separately, so only half the condensate will feed back to the sub main (each radiator condensate has it's own path back to the sub main).
2. the condenstate is flowing back down a 45, instead of trying to get through a vertical T, and then making a 90 degree turn into the sub main.

OR, for repiping, could I 45 off the sub main, and then 45 from one radiator feed to the other? And then control steam to each radiator by adjusting my Hoffman vents (one being fast steam venting and one being slow steam venting)?

I can take a few photos and post them tomorrow, to provide a better idea of my piping.
Thanks in advance for any help!
Pat

pmchale

Inserting some photos to go with the piping description

Jamie Hall

"I am considering repiping these Tee's coming off the sub mains, and replacing with separate 45's off the sub main instead, so that:" That should work. I won't' guarantee that it will stop the hammering, but it certainly should help. There are several interesting places to trap condensate...

Be very sure when you are doing the repiping that the "horizontal" sections of the runouts have adequate pitch. If they go into a vertical by just one 90 elbow, it sometimes happens that you can't flex them enough to get adequate pitch -- which case you can make the transition with a 90 set horizontal, close nipple, and a 90 turning to the vertical.

acwagner

@pmchale in one of your older posts you had this photo:



Do the radiator take-offs that you want to change come off this branch setup? If so, the pooling water is more likely at one side or the other of this intersection. It would be best to go all the way back to this point and have individual take-offs for the radiators. Or redo the main so that instead of tee, have one side come off at a 45.

I assume your system is a counterflow setup?

pmchale

Response to acwagner: Yes, the radiator take-offs come off the branch in the older photo you illustrated (two sub main branches off that T). If I tried going nearly back to the T off the main, and run individual take-offs to each radiator, how exactly would I split the piping for individual take-offs (sorry, I am a homeowner that has done a lot of reading, not a heating contractor)? My guess is something like a nipple on each side of the T, then a Y that would split to two smaller runs, essentially running parallel, until they head up toward the single near risers for the individual radiators...?
I am more apt to try something like this, versus dealing with the long main and T, which would be a big job, since the other side of the main also comes out of a T (with another sub main), which would likely have to be broken off, and cause me to have to deal with that 3rd sub main...and on, and on, ha.

acwagner

If I understand your description correctly, yes that would be a big job to re-pipe.

Have you put a level on the sub-mains to see if they have any pitch? Also try a long straight edge to see the pipes are sagging or bent. That would help focus the effort.

You could also drip the offending area, if you have some wet returns to tie into. Not as elegant but could get the job done.

Actually, a lot of the fittings going to the radiators look newer. Is your system counterflow or a parallel flow?

pmchale

To acwagner - Yes, we did some repiping last year, but only to add Gorton vents on the submains, since we were not getting heat fast enough to that side of the house. The vents helped, but now I have more hammer. Um, I believe my system is counterflow...no wet returns, just one pipe system everywhere, with steam and water condensate using same pipes. The sub mains do pitch toward the main, but perhaps more is needed. How much pitch per foot is required? I do have that info in Dan H's books, just not with me right now. But I would be happy for you to tell me proper pitch.

Again, separating the runs to individual radiators (first floor and second floor) from each sub main seems like it would really help with the hammering, and be a bit less of a job. So would I repipe as I suggested in my previous post, or some other way that would make more sense? I am willing to try some more repiping/modifying. I do know not to mess with changing the pipe routing too much, for fear of really messing things up...

acwagner

For counterflow, it's recommended to be pitched at least 1 inch per 10 feet of pipe. All the pipe in your photos you want to be pitched at least that much.

What you described for your radiator take-offs is the recommended practice. I would still investigate your submains more. I think they are the more likely culprit.

It's an unusual setup. I wondered if the newer fittings on the radiator runouts meant that there used to be a drip on them and someone removed the drip for some reason.

pmchale

OK. Nope, no old drips removed. Will check all pitches to be sure. Will comment back with news, or if more advice needed.
Thanks very much (including others who advised)!

pmchale

@acwagner - one more thing...hear is my repipe design. Is this a proper way to split the radiator run-offs individually?

acwagner

Is your sketch a top view or a side view?

acwagner

Also, what's the EDR rating for the two radiators served by this? I don't have the references with me, but 1 1/4" pipe is probably too small to service both.

pmchale

@acwagner
Sort of top view, tough to illustrate exactly in 2D. I was thinking both run-offs would bump up off the sub main via T's angled to meet 45's with short nipples. Basically, get the runs up off the mains at 45 for better counterflow, and also 45 up to the risers, for same reason. Trying to eliminate hitting fitting walls as much as possible...which there is plenty of that going on right now.

I would have to calculate the EDRs, but you may be correct on pipe size. So running off to the radiators individually would certainly help with that, correct?

acwagner

Ok, makes sense. Multiple ways to approach this, yours being one. The common section with the "vent?" label is the area that the pipe size needs to be double checked. Actually all the piping needs to be checked. There are several rules about runouts and risers based on the EDR of the radiators. Dan's book has tables for those to double check.

Also, having the main vent at the end of the line like that isn't a great location. It will likely get damaged. I would put the main vent at the "Vent?" location. The radiator vents will handle the runout/risers.

An alternative piping arrangement is to have all the radiators take off directly from the main in series where the tee is. That involves removing the Tee though.

I still think the sub-main tee is the source of your problems. The hammer is from pooling water. With the main tee like that I don't see how one side isn't pooling water, but maybe the pipes are bent slightly up to give it pitch. I just wouldn't trust that approach on an old home that has settled over time.

pmchale

@acwagner
OK to all that. The thing is, there was no hammer until we put the present Gorton vents in last year, so the main t'ing to the two opposing sub mains was not a problem before. We were pretty careful to keep pitch when vents were installed, but maybe something go thrown off...
I think running all four radiators off the main, individually, is a bit much to handle, and again, would require breaking another T up the line, towards the boiler, causing even more work to do, with more piping. So probably not going that route, but will certainly keep in mind.
I will calculate EDR of radiators/pipes.
Thanks!

acwagner

I looked at your older post that had a schematic of your steam system layout. It's fascinating that it works without any major problems other than hammer at this one spot. It seems to violate all pipe sizing rules and conventions.

It would be interesting to know the total EDR of your system.

Whoever built it was either an extremely lucky knucklehead or a mad steam genius.

KC_Jones

Most likely the vents allowed for proper steam flow which now presents the deficiencies in the piping. You want the steam moving to heat the house, but the piping has to be right in support of this.

On coal the steam moved slowly and probably never showed the issue. Just my guess.

pmchale

@acwagner
So if you had free reign to redesign, within a not too overwhelming budget, how would you repipe the side I am having trouble with (the main and two submains with their pairs of radiators)? Just curious. You mentioned the 4 radiators all individually running off the main...would you consider that a design that would have a high probability of solving issues? I hate to just throw money and parts at this, hoping that it COULD work. And would really hate to do a redesign and find out that it did not help at all. But my wife is really getting tired of the water hammer alarm clock at 5:15am, ha.

acwagner

I'll try to sketch something up for you. Difficult to describe in writing.

Knowing the EDR of the radiators that will be connected is a must, in my opinion. You want to make sure the pipe size is adequate to handle the connected load.

You didn't have any hammer until you put the main vent on? The only problem was the system wasn't balanced? Did the piping have insulation on it before? It appears it did from your photos.

pmchale

@acwagner
The original system had the main with a T splitting to two sub mains, as it still does. We had little hammer or none, and the system was simply unbalanced - with the 2nd floor radiators on that side of the system usually not getting sufficient steam. Last year, we did some minor repiping to install two Gorton vents, in order to get the air out quicker, in hopes of getting steam to that side more quickly. That is when the hammer started. Funny, because after that work, the system operated really well for about a month, and I was hopeful, but then the hammering started, and has continued ever since. So the main T'ing off to the two sub mains was not causing hammer before.
I am hoping to get EDR calcs done this evening, now that I have located my steam books (Dan H.). I will also measure the length of piping and their diameters.
Oh, and no pipes were insulated when I bought the house. At some point, someone removed the old asbestos insulation, which is obvious from a little bit of residue left in a couple spots. Any insulation you see now, has been installed by myself. I was waiting to finish insulating, when I get the system working better, so some run-offs to vertical risers are still not insulated.
I really would prefer to do a bit more repiping, but keep the main T'ing to the two sub mains, since that did not hammer before, and it would be a big, more expensive job to install a new main, with 4 run-offs for each radiator. I would prefer to just try splitting the the two radiators on each submain into 2 separate run-offs, if there is a decent probability that it could work.

No EDR and measurements until at least tomorrow morning.
Thanks!

acwagner

It's likely this system worked when it was installed, otherwise it would not have survived to present day in it's current form.

You might be able to get it to work right as is. What's nature of the hammer--only at startup and isolated to this one area?

You might want to try insulating the pipes in that area first. It may be that the pipe diameters are not large enough to handle the condensate and steam with no insulation. Insulation can be reused, so it wouldn't be wasted.

pmchale

@acwagner
Hammer is mainly at startup, and isolated to the side of the system. Will insulate this weekend and see what happens, or not. Will still do EDR calcs, and pipe measurements.

acwagner

Well, this is what I was thinking if you end up re-piping. Attached is a rough isometric view.

Kind of a hybrid between your plan and mine. This would probably be the easiest to pipe given the orientation of the piping to the joists.

pmchale

@acwagner
Sorry, but your file does not want to open as a pdf...I just get a bunch of nonsense text. The attachment shows it as a pdf file, but the entire file name is in quotations, which is odd...If necessary, I could provide my email, if you think that is OK.

I did some EDR calcs and pipe measurements:

sub main right side: 2nd floor radiator EDR = 32 + first floor radiator EDR = 46; Total EDR = 78. This is fed by a 1.5" submain and 1.25" runouts. Per charts, 1.25" runouts can handle 64 EDR, so perhaps this is a little undersized.

sub main left side: 2nd floor radiator EDR = 20 + first floor radiator EDR = 32; Total EDR = 52. This is fed by a 1.5" submain and 1.25" and 1" runouts. Per charts, 1.25" runouts can handle 64 EDR, so perhaps this side seems OK.

Insulation - both of these 2 radiator runouts nearly butt up against the uninsulated rim joist, which certainly cannot help the situation! I plan to insulate between the steam elbow and riser and the rim joists. This won't help with hammer, I doubt, but it may help to get the steam up the pipes more efficiently.

acwagner

I'll try PM-ing you the file instead. Not sure what the issue is.

The tables should be for runouts to risers that are not dripped and condensate flows against steam.

1" = 28 EDR
1.25" = 55 EDR
1.5" = 81 EDR

I believe these values are also predicated on having the right pitch, which for your sub main probably isn't the case.

Is the 78 total EDR branch the side with the hammer? That's right at the limit of the 1.5" counterflow. I'd definitely try insulating that first. Insulate all the straight sections, including radiator runs outs, the main, and sub-mains. If you end up re-piping, you can remove the insulation and reuse a lot of it.

My guess is that with no insulation the EDR of the pipe is pushing the total EDR above what a 1.5" can handle, and the condensate's flow is being impeded by the steam pushing against it.

Just a guess, but a relatively easy thing to try first.

ethicalpaul

You can remove the apostrophes from the file name on your downloaded copy then it will open as a pdf on your computer.

I tried re-attaching it on this message, but the site seems to add the apostrophes during the download. Any idea why, @Erin Holohan Haskell ?

I attached it as an image file here for convenience

acwagner

Thanks, @ethicalpaul. I ended up sending it to him as a screen shot like you did. For the benefit of everyone, thanks for posting.

We were discussing in PM location for main vent. What are your thoughts? I was suggesting on the main between the old bull tee location and the 90. But there appear to be a number of options.

Also I realize rules for radiator run-out slopes vary based on if it's first floor, second floor, servicing multiple rads, etc. I just put a generic slope on there for counterflow pipes since I don't have the specifics. Open to opinions on that as well.

ethicalpaul

I would lean toward that last 90 elbow on the right, but I'm a little fuzzy on how this system will be regarding wet return, etc, and I'm not very knowledgable about counter-flow.

Erin Holohan Haskell

ethicalpaul said:

I tried re-attaching it on this message, but the site seems to add the apostrophes during the download. Any idea why, @Erin Holohan Haskell ?

Thanks for the heads up, @ethicalpaul. We had a similar issue on another thread and are looking into it.

pmchale

I have been PM'ing with acwagner (many thanks to him!) about my system & possible repiping. Neither of us is a steam pro, so we were considering where to put venting to balance my system. The first picture is my current entire system. The problems include unbalanced heating, especially to the 2nd floor master bath and master bedroom (top of the drawing), and some hammering (definitely from the area considered for repiping). The T's on each side of the main seem to be a real bottleneck. After lots of reading, etc., I really am perplexed as to why they were piped like this. acwagner proposed something like the other included photo (dated 111219), with single runouts to each radiator...this makes sense to me. I have proposed a main vent at the end of the main, after the two submains T off to surface two radiator runouts each.

The right side submain is much longer than the left side (about 8 ft, vs 3.5 ft), so should I also vent near the end of the right side submain, and if so, exactly where?

FYI - all pipes will be properly pitched and runouts will 45 into T's/90's at the submains...this should be a much more efficient system, in terms of counterflow, I hope.

Any thoughts would be most appreciated, mainly concerning where to locate the vents for the repiping.
Thanks!

pmchale

@acwagner
Greetings - For the last 2 days (M-Tues), my contractor and I did plenty of repiping and added more venting on submains (Gortons), per your schematic and our discussions. It has only been one full day, but our one-pipe system is balanced MUCH better, and I could not even tell that it was calling for heat this morning, since there was zero hammer, etc. I am hopeful that it will continue to operate this well. Just wanted to pass on an update, and say "thanks" for all your help, as well as a few other folks on this site! Very much appreciated.

acwagner

That's awesome! Glad to hear all the repiping paid off. Got any photos of the new work?

pmchale

@acwagner

BobC

Rhat's good looking work, glad to hear your hard work paid off. The boiler will have to be skimmed in a few days as the oils from the new pipe make their way down to the boiler. The pipe hanger in your picture will not last, over time it will stretch and let things sag. Get a real pipe hanger in place before that happens.

Bob

pmchale

@BobC
Plan to skim boiler, but it is a Burnham Independence, that apparently gets skimmed off the PRV, once it is retrofitted. WIll attempt. Hangers - correct, my contractor used those, but I have proper hangers to install in place of the strapping.
Thanks!
Pat

BobC

Page 6 of the i/o manual shows a 1" tapping for the blowoff (AKA skimming) port on the right end casting. You might want to put a pipe and cap so you can skim whenever you want - make sure to use teflon tape on the cap so it comes off easy.

If you want yo can cut half the end of a spare 1" cap to give yourself a 1" lip, that will skim a lot quicker. You could also just cut a 1/4" slot in the cap to do the same thing.

Bob

acwagner

I've gotten good results skimming using the PRV port on my Independence boiler. I just piped in a Tee on the port so I didn't have to keep removing the PRV when I wanted to skim it.

pmchale

I attempted skimming by removing the PRV and replacing with a 90 and 24" - 3/4" pipe length, as the PRV is close to a wall (not real convenient). I was able to trickle flow for a couple hours, so we'll see. I plan to do some more skimming and then draining/flushing next weekend.

@BobC
I will consider your advice too. So that tapping is on the same side as the PRV, and on the other side of that right end section? That would be easier, as the PRV tapping is more difficult to access.

dopey27177

Attached drawing for corrective piping.

I apologize for the the poor drawing and writting as my hands don't work as they used to.

In one drawing I use the water seal to divert condensate from the affected area to a location closer to the boiler.

I have used this for many years on both one and two pipe steam.

Jake