Near Boiler Piping Question

Brad White_57

Mel,
For pitch, generally 1/4" to 1/2" per foot should be sufficient. Runouts to radiators should pitch upward at the 1/2" per foot rate; drips to wet returns also should follow that 1/2" pitch rate. The main header should not be less than 1/4" per foot though.

To pitch a header, don't consider rising to an elbow and leaving the elbow to make the downward pitch. That would put stress on the elbow, riser and rapidly, the boiler.

Rather, rise to an elbow, turn laterally for at least a foot, add another elbow and pitch the line that leaves the second elbow. Think of a giant hairpin or "Z" configuration.

Properly made, the joints should not pose a problem. The upward expansion of the initial riser (say 3 feet or so, installed at 50 degrees temperature) will expand about 4/100ths of an inch when heated to steam temperatures. The main will exert forces along it's length away from the boiler, imposing the stresses along the tees feeding the radiators. Those tend to be long and relatively flexible.

Done all the time, do not worry about it. Just make up the joints properly as you would anyway.

EDIT: Do as Steamhead says and does, and as Matt "Mad Dog" Sweeney has done. Dropped headers are the bomb.

Nothing to add to that.

mel rowe

Near Boiler Piping Question

Since the heating season is over and I have a lot of time before needing my boiler again, I am working on correecting the piping mess I have lived with for so long. Several questions have already cropped up. In Dan's book I read that the header should be pitched so that any remaining water will drain when the system shuts off. How much is recommended and how in the world do you get it, with ridgid piping? Will the universal joints allow that much out of alignment and still seal? What about the water that will collect along the edges of joints in the header? Is that a concern for water hammer on startup? So many questions and so little experience. Good thing I have lots of time. Thanks.

Steamhead (in transit)

Mel, if you want to see it done right

look no further than these Drop Header photos:

http://www.heatinghelp.com/library.cfm#Steam Piping

What boiler do you have now?



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mel rowe

Thanks Brad and Steamhead. I have studied the photos of drop headers a lot. They gave me the confidence to try this myself. In studying the photos, it did not seem there was a pitch on the headers. Maybe it was just too subtle to pick up in the photos. Since you convinced me there is a pitch there, and I need to do the same, I'll try and follow your directions. I have a Utica boiler, and one of the photos looks very much like what I'll need to do. It does seem that if I put a 3/4 -1 in. pitch on the header, it will be difficult to line up the vertical return to the equalizer coming off the end of the header. Is the piping flexible enough, with a universal in the vertical line that it will line up okay? Also, with all those joints in the header, won't there still be small pockets of water that collect inside the elbows and tees, at the end of the nipples?

Brad White_57

Dropped Headers

Hey Mel-
In the photo of Matt and His Boiler, the initial risers you can see go up-over-down into the top of the header. That portion is probably close to level. The header is large (2.5 inch it seems to me) and the flow of steam carries any condensate clockwise to the portion on the left which does pitch noticeably.

The initial risers alone bring mostly steam, leaving the water behind. Whatever little may be carried and whatever is formed in the header on warm-up is insignificant compared to the diameter of the header.

Do not worry about the equalizer drop- you can see Matt used a 90 and 45 El to offset accordingly. I can assure you if Matt did it, it is plumb vertical where it counts. No, you do not want to think that you can bend or force the pipe into place. Long pipe and a fitting is a lever. More force than you think. Do not go there.


Matt he used unions and you should too. You will have to. Unions are essential not just to remove parts, but to allow fabrication of otherwise "dead-end" assemblies. You have to stop screwing pipe at some point or else you hold the pipe and turn the world

Header joints: First of all, if you use any reducers, they should be eccentric and flat on the bottom (common bottom plane to drain). Do not be concerned about little driblets collecting.

With a properly (generously) sized header, there is plenty of room to have steam pass above and what is practically a film of condensate on the bottom. That condensate will be carried along or re-evaporated in very little time. You just to not want an accumulation to occur that interferes with steam passage. That is where the pitch comes in, to move it out faster than gravity (gravity + steam velocity are the forces at work here). No worries.

If you have any concerns at all, have a pipe fitter make up a Schedule 40 welded header with weld-o-let tappings for where you go back to screwed piping. It may cost more than your DIY efforts, and not to disparage your work efforts, you will have a nice, smooth track in which to run your gentle steam. It will take a good bit of precise measurement to get it done right but you can show it off when you are done!

You are to be commended for taking an existing boiler and giving it a new lease on life with new near-boiler piping.

mel rowe

Thanks Brad. I'm correcting a 17 year old mistake that gave me lots of problems that I never really understood until reading Dan's book. My Utica boiler was installed with only one riser. By my calculations that created steam velocity of 54 ft./sec. leaving the boiler. Needless to say I had lots of wet steam and related problems. I'm going to correct that by adding a second riser from the boiler. These two 2 in. risers will tie into a drop header that will be made of 3 in. pipe and fittings. Right now I have a two in. riser that splits into two 2 1/2 in. mains. I plan to revise to two 2 1/2 in risers (from the drop header)into the two mains. One thing I am curious about is that I saw on two of the drop header photos in the library that gate valves were installed in the risers, just ahead of the mains. Is this just to allow for a shutoff of one of the mains, if desired for some reason, or to allow for balancing the flow in the mains? I wondered about this because one of my two mains handles about a 35% heavier load than the other. Would this be a way to balance the system?

Brad White_57

I would not consider gate valves to be balancing valves

not for a second, Mel. Gate valves are to be 100% open or closed, nothing in between. I figure if there were two risers with gate valves but each serving a separate run, that would be to isolate half. But if a common header was served, I see no need, no point. (JMHO).

In commercial/institutional work one would isolate each boiler at the header, but a single boiler with two isolated feeds serving a common header escapes me.

Your saintly and patient Utica might ask what took so long, but like having a major organ transplant, the remainder of it's life will be eased.

With your 3 inch header fed by two 2 inch risers, that sounds fantastic. And I trust that your out-feed pipe will start downstream of and not between the two risers, right? Right? Never leave the header between two boiler risers. Bullhead tee condition and your own personal tsunami.

Please post photos!

Brad

mel rowe

Thanks again Brad. Both my outfeed pipes will start downstream of the second riser from the boiler. I did learn that correctly. I wasn't very clear previously, but the valves I was wondering about would be on the outfeed pipes. I noticed them on both Matt Sweeney and Alex Marx's photos of their drop headers. It just made me curious as to whether that might have any benefit to balancing my system. Another thing I thought I would do to try and get as dry steam as possible is to have long risers from the boiler up to the header. I know Dan says 24 in. above the center of the glass gage, but I thought I would extend even higher. It may be awhile before I get this done, but I will try to post photos.

Brad White_57

Valves on the outfeeds of Matt \"Mad Dog\" Sweeney's Boiler

Mel,

Matt did have valves on the outfeeds, not what I thought you meant. I would assume that those valves would be for isolation. Best bet rather than guess is to ask Matt himself. Matt?

The 28 inch "A" dimension is a minimum. I see no harm going higher. Remember the A dimension is from the lowest point of your steam header/main which would be near the end of the run before dropping to the return. Loss of elevation can sneak up on you. If you have height, I would use it.

mel rowe

Thanks Brad, Am I ever glad that I asked that last question. When Dan talks about the A dimension,relative to the header, I didn't think of it in terms of a drop header. Until you brought it up, I was thinking of the A dimension only in terms of the maximum height of the upfeed risers, before they drop down into the header itself. Now I realize that even if I had installed max. ht. upfeed risers, if I had also dropped the header down too much, I might have messed up the whole thing. Lots to learn.

mel rowe

The original installation in 1929 was two 2 1/2 in. mains that were tied together into one 2 1/2 in. pipe into the old header. As I repipe the current header to correct a 17 year problem that was installed when I got a new boiler, does it make any sense to split the mains and tie them in separately to my new drop header of the future? There will be plenty of room to do so, I just wasn't sure if there was any advantage or not. Thanks.

Brad White_57

If you keep in mind the purpose

that the A dimension (28 inches minimum from low point of active steam to waterline) serves, it will all make sense. The 28 inches (27.72 to be precise) is the height of a column of water that corresponds to and imposes one pound per square inch pressure. During massive warmup, slugs of condensate will fill that temporarily and force condensate below it into the boiler, all without a pump.

It is one of those things I never considered years ago. Glad you asked too!

Brad White_57

To Split or not to Split, That is the Question...

Mmmmmm. I suppose I would need to see a photo to take on that one, Mel.

If the mains were once separate and going in different directions, I see no harm in restoring them to their former presumed balance. Rising from the header and turning with an elbow would look more elegant than a single tap into a tee on an older main. Just MHO..

If they currently are joined as one and the connection to the new header would be into a tee, I can see a minor "bullhead" situation where the steam enters the distribution main and has to split left-right. I guess the question is, what would the size of that connecting line be relative to the main it is serving?

I think sight unseen, the way I would tackle this is to ask: "Of the two methods, which one preserves your design goals of lowest velocity?"

mel rowe

Brad, I see no evidence that the mains were ever separate. Perhaps a better description would be ---one long (85 feet) main with one 25 ft. sub main. Both are 2 1/2 in. I described it this way because the sub main is teed off the long main about a foot before the first elbow, so there is no minor bull-nose effect. I'm not sure if the possibility of imbalance between the two would be worse as is, or if I tied each main in to the header separately. I have installed a Gorton no. 2 on each of the two sections, so it seems that with that level of venting, even if the mains were imbalanced, both would be purged of air before any rads start to fill with steam. This balance question is one I had no idea about, so that is why I was asking about the valves I saw on the two examples of drop headers that I mentioned, and if system balance might have been the intent. Even though my two boiler tappings are 2in., I can certainly consider making the header any size between 3 and 4 inches, and the outfeed lines could be anything up to the 2 1/2 in. I have in the mains. I could even pipe the shorter main with a smaller outfeed pipe than the longer main. I guess I thought there might be some value in separating the two mains, and I am willing to do the extra work, but I just don't have any idea of the relative importance of trying to balance the two. I really do appreciate all your time and patience. When I learn yet another skill (posting digital photos on the Wall), I promise that I will do so, just to show that all your good efforts were not in vain.

Brad White_57

I would leave them combined, Mel.

If we just allow steam, a gas, to do it's thing, (not to mention proper venting) all should work out just fine. I do not think you could detect a difference in performance, split or not. My concern was one of geometry and collision-avoidance. The steam should find it's way evenly and quickly.

Are you also changing to a Vaporstat versus Pressuretrol by the way?

The generous sizing of your main header (and I have to presume your 'running mains to EDR' ratio -but I have no idea what your connected EDR is!) should yield adequate results even if it were a "from the ground-up" installation.


Given that this is to be an improvement over the past 17 years, one has to admire the effort. Almost makes you eager for the first chilly days of fall so you can test run the new baby, doesn't it?

mel rowe

Brad,I calculated the EDR for my system as being 938 sq. ft. After applying the 1.33 factor, my first reaction was that my Utica boiler was way undersized, since it was rated at 760 sq. ft. Then I stopped and realized that even on the coldest days we see here in my part of Mich. that the boiler is only running about 35-40 % of the time. So my only rationale is that the system was originally designed for the insulation conditions of a 1929-built house. Since moving in, I have added thermopane windows, foam in the walls, and 8 inches of icynene foam in the attic. Clearly the boiler is more than adequate. Regarding your question about the Vaporstat, I was seriously considering doing that, but have had second thoughts. I have changed all my main vents to Gortons, changed all rad valves to TRV's, changed my pressure valve from 0-50 psi to 0-5, so I could actually see what the pressure was. During playing around with the Pressuretrol, I actually got it to shutting down at about 1.3 psi. Plus the system seldom gets above 1 psi before the thermostat shuts it down anyway. So I just wasn't sure about the potential benefits from the Vaporstat. I'd be happy to reconsider if there is more to be gained. I'm also happy to follow your suggestion and leave the mains tied together. Thanks again. Have a good one.

Brad White_9

I agree, Mel

The vaporstat would do little to improve things. Steamhead and others feel free to chime in. Something about positive control in ounces has a certain appeal. But already you are running much lower than you had been. Once you re-pipe that might be an additional enhancement.

You really did the envelope proud, Mel! Wish I had done so. Not sure why the boiler versus radiation works as well as it does, but perhaps that your mains are insulated -I assume- the perhaps also your 768 EDR boiler rating is net not gross. Rightly sized if that is the case.

Nice project overall! Best of luck to you.

Brad

Steamhead (in transit)

Mel, does your Utica look like this photo?

if so, it's the same model series of boiler. The one in the photo is sold by Columbia. Be sure to provide at least one tee with a plug in the run for skimming and flushing.

Regarding the split-off of the steam lines- if the tee at that point is "bullheaded" (where steam comes into the side tapping and tries to go both ways) it would be worth repiping.

What type of system is this? One-pipe? Vapor? How about positing a pic of the current setup?



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Steamhead (in transit)

Mel, does your Utica look like

the third one in the "Drop Header Photos" PDF file in the Library (maybe without the louvered cover over the burners)? If so, it's the same model series of boiler. The one in the photo is sold by Columbia. Be sure to provide at least one tee with a plug in the run for skimming and flushing.

Regarding the split-off of the steam lines- if the tee at that point is "bullheaded" (where steam comes into the side tapping and tries to go both ways) it would be worth repiping.

What type of system is this? One-pipe? Vapor? How about posting a pic of the current setup?



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mel rowe

Steamhead, the boiler for my one-pipe system more closely resembles the second from last of the drop header photos --- done by some guy named Wilsey. LOL The piping also looks like my current plan, except that I will have only one outfeed to the mains, and the wet return from the end of the header will drop straight down into the equalizer. I was also planning to use a 3 in. header. There is no bullhead in the system and there are already plugs that allow for skimming and draining. Thanks.

Steamhead (in transit)

That

should work fine. Let us know how well it works. Also, make sure your mains are well vented- this will make the steam distribute faster and further reduce burner run-time.

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mel rowe

Thanks Steamhead. One of the first things I learned from the Wallies was about Gorton No. 2's. I already have installed 2 in my system, one at my daughters, and one at a friend's house. In each case they made a huge difference. The Wall is a great site, monitored by very experienced and helpful people.