main venting doesn't matter?!?

jpf321

as some of you may be following, i have been running cycles over the last few days and putting up charts of the data over here: <a href="http://www.heatinghelp.com/forum-thread/129007/quantifying-savings">http://www.heatinghelp.com/forum-thread/129007/quantifying-savings</a> .. my most recent dataset this morninng pointed me towards the idea that main venting doesn't matter...and then I started writing up the below dribble...but i thought it warranted some discussion...



we all talk about path of least resistance and filling the mains before

the risers and before the rads .. but how can we actually control the

flow of steam .. air doesn't just stand there and push back .. this a

dynamic flow of fluids ... air heats up, air moves, steam condenses,

steam fills voids and vacuums and all sorts of things are happening

BEFORE pressure blocking forward movement is exerted on the steam..



the

steam will only stop moving once it meets a pressure of air that is

equal to the pressure from the boiler..and if dan's analogy about the

busses and beetles holds true, steam moves lightning fast at a pressure

difference of just fractions of an ounce.



i dunno, this is all making

my head hurt .. but i'm starting to convince myself that proper rad

venting is more useful (and cheaper) than main venting...maybe I have

slow steam that meanders around and everyone else's steam heads straight

to the end of the main and out the main vent. maybe the size of the

mains matter more in bigger systems, but then you also have more rads

sharing the venting load.



maybe a 3-story single-fam-residence is

special in that it won't help to vent the mains...and that larger apartments and office building and such require a main venting solution..we all know that a portion of a rad will get hot even if plugged..steam has to investigate every nook and cranny before it decides (or is met with) opposing pressure that prevents further infiltration.



i wish i had numerous (13 more actually) Lascar TC loggers (if anyone wants my shipping address let me know) .. and I had one on each rad inlet.. to then get a very good picture of the system with and without main vents. right now i'm limited to the data i have .. and i feel good about the test .. and it shows main vents don't matter...



i look forward to the data and tests of others as they receive and install their Lascar loggers (i know there are at least 2 of you) .. i encourage other data and analysis that proves that main vents alone = less fuel... I know that perhaps it was DavidK that said he did alot of testing once... and perhaps there are more folks out there with vent/no-vent datasets... please share.



thanks for listening & thinking.

DavidK_2

It wasn't me

that did testing of main vents.



I must admit I'm puzzled by your results - unless your radiators are well vented.

What happens if you remove the main vents from your spread sheet? Does it effect any timings? It is curious that physics/math says that main vents matter, but measurements show that it does not - would suggest a gap in our understanding . . .

Brian_74

Could your system be compensating?

Do you think that your individual radiators are so well vented that when you took away the main vents they took over the task of venting?



BTW, I think this is neat what you're doing and I appreciate you sharing your data.

jpf321

removing mains

if i remove the line items for the mains in the sheet, i'd have to come up with a way to reallocate the CF of the mains .. i think it's just as well to consider that load is shared equally over the 7rads on that main .. and figure that each rad must vent an extra 0.214CF ... however, without having a thermocouple meter on each rad, i do not know if the load is being equally shared .. since I am currently measuring the last rad on the main located on the 3rd floor, i must guess that the load is being shared pretty well otherwise it would not have gotten steam in the same timing.



with a meter on each rad (14), and boiler (1), and end of mains (2), i could precisely pinpoint the flow of steam through the system .. the more sampling points the easier to visulalize... i guess i know what i'm asking for for my birthday ... but that's end of Feb.

jpf321

well that has to be the case...

it has to be the case that the air must have gone somewhere ...

fyi, i did make it a specific point to see if I could *hear* any overworked vents while I was running these cycles (no i don't sleep, especially with an under-the-weather wife, a 2yr old and a 10wk old) .. i heard nothing...



and FYI, my vents are extremely silent on the way up, and only sometime whistle on the way down .. mainly b/c i usually don't break 1oz on runs of that length... i stood in front of my gauge without my vents hoping for the pressure to rise, but it never broke a sweat....and that too may be part of the problem .. i may have to run a 3dFahr t-stat jump and compare that with/without vents...that should get my oil gun working.

DavidK_2

I haven't looked at your spread sheet

does it neglect the role of rad vents in helping to vent the main? When the boiler first fires all vents in your system and helping vent the mains.



You are heading down a slippery slope - next you'll want pressure transducers on all your radiators



Did you do manual timing before and after adding main vents?



If you truly determine that main vents make no difference, you are going to have a lot of posts to edit!



I'm guessing you are a retired engineer, and this is you new hobby. Am I close?



Anyway, again, fun stuff and thanks for sharing

jpf321

in the spreadsheet..

in the spreadsheet and in Mr. Gill's original paper, all equipment gets vented as a unique entity... this was actually an interesting question that was raise a couple of weeks back .. if you have a main ABC.. and you have vents at B & C, do you calculate the cubicfeet from AB and AC or just AB and BC .. i argued AB and BC .. but then the gentleman responded with an intriguing point which I hadn't considered .. and forgot what it was...



so in answer to your question .. each rad is calculated to vent from the main to the end of rad including the riser for the rad...and taking something out of the system does not affect other things.



i'm not retired, and i'm not an engineer,  i just try to think like one. i'm one of those "has enough knowledge to be dangerous, yet not enough to no better" kinda guys...



I think Mike K. over in the $$$ thread has a good point .. b/c I was running cycles fast and furious, the water held more heat and therefore it compensated for the missing vents. i have the vents in place now and I hope that I have the nearly same temps outside tonight and cycles inside... this thread may be proven wrong in the morning.



i did indeed do manual timing to end of mains and other places before and after vents .. and at that time i was a convert and believer .. read through this thread for when I was doing various things .. http://www.heatinghelp.com/forum-thread/128365/Looking-for-a-Steam-Pro-for-site-survey-visit



stay tuned..

Unknown

Main Vents

HI Jpf- Thanks for sharing your data. It's very interesting.

Edit: I have edited out my original reply as Gerry Gill's message bothered me as in re reading what I had wrote, I realized that it could misleading to anyone reading it and they might think that possibly main vents weren't necessary.  Main vents are very necessary!



 Theoretically if we have tremendous venting capacity on the radiators, multiple radiators and a grossly oversized (133%+  pickup factor) boiler, main vents might not be required, however this is NOT "real world".  When I read this I immediately thought of Boiler Pro's article as he addresses venting on radiators and main vents using less pickup factor.

[url=http://www.heatinghelp.com/article/11/Hot-Tech-Tips/1551/Taking-Another-Look-at-Steam-Boiler-Sizing-Methods-by-Dave-Boilerpro-Bunnell]http://www.heatinghelp.com/article/11/Hot-Tech-Tips/1551/Taking-Another-Look-at-Steam-Boiler-Sizing-Methods-by-Dave-Boilerpro-Bunnell



As fuel costs seem to be rising again, the concern for fuel economy should increase so we may finally see some sophisticated computer controls and modulating burners for steam. If we are able to reduce the pickup factor from the boiler size, we're going to have to re think venting as then good main venting (per Boiler Pro's article) becomes very important. 

I've often wondered whether there are possibilities in using a small boiler and rotary/demand zoning, but haven't penciled this out as yet. Has anyone read any articles on steam zoning?

- Rod

DavidK_2

I see now

a 2yr old and a 10wk old. Probably not retired - but probably pretty tired

gerry gill

i think you need

to get into the field for awhile..cause if you think main vents don't matter i think your nuts..

Jamie Hall

Gerry's right

there's no substitute for getting out into the field.  The problem is that the flows in a steam system are ridiculously complex, even in what seems to be a fairly straightforward one pipe system with one or two mains.  Never mind anything more complicated.  It would take a very complex finite element model and computer simulation to model and compute what is happening on a computer (I know; in another life I used to write those things for people) -- and all it would do is confirm what is clear from a few minutes in a basement with a firing boiler.  Main vents make a big difference.



I can certainly see possibilities for using very sophisticated computer controls and valving to possibly reduce the need for including the piping pickup loads in the boiler sizing.  However, simply coming up with good modulating burners can accomplish much the same purpose (assuming that you have really good proportional control based on very small pressure changes -- a big assumption) and would be very flexible in application.  Along those lines, it is absolutely fascinating -- and very instructive -- to look at the proportional controls used back in the day of coal fired systems.  They did a wonderful job of controlling the fire so that the steam pressure held remarkably constant (within a few inches of water gauge) over a very wide range of loads.  Trouble is, they only worked on coal (and only if someone remembered to stoke the fire!) and the efficiencies and air pollution which resulted at low loads were truly horrible.  Some, though not all of them, were also arranged with linkages to a mechanical thermostat, and the end result was a truly Heath Robinson arrangement of levers and cables and pulleys and floats...



As someone's remark under their signature says, here on the Wall, steam heat isn't rocket science -- it's actually much more complicated!

jpf321

Mr. Gill

Mr. Gill -



You wrote to me once in an email "anything that advances steam is generally fine with me" .. well your comment above and your previous comment directed at me here http://www.heatinghelp.com/forum-thread/128933/christmas-present-to-myself do nothing towards advancing my enthusiasm and interest in continuing to learn. Additionally, it has caused censor of Rod's post above which shows that comments such as this hinder investigative discussion on topics in the community.



If you actually read my post, I am looking at things with a skeptical eye but I am not claiming to know the answers..I am only putting forward something that I believe "warranted discussion". Much of my post is, as I noted, dribble, but I thought it may be thought provoking and interesting to consider given the data that I received. You will also note that in my follow-up replies, I was quite open to other explanations as to the results that I obtained. As I noted clearly as well, I am very eager to hear from others as to their real-world or data experiences.



I'm a new guy here, but I think that during my time here, I have tried the best that I could to offer my assistance, and to acknowledge my misinformation or improper advice if it was pointed out to me. I think that others here have appreciated my input, or maybe not. I have heard from several people both openly and privately that they appreciated my little spreadsheet, the historical pieces I've uncovered, my sharing of the data that I was collecting. I do think that these things have "advanced steam" albeit in a small amount compared to the breadth of information and centuries of combined real-world experience which exists here.



I'm enthusiastic, perhaps overly so. I'm eager to learn and experience but I have only my home to play with. I'm intelligent and I think that having been here for little over 7 weeks, I have for the most part "gotten it". I think that having "new eyes" in the community has perhaps on at least one or two occasions directed someone towards a solution or consideration that hadn't been previously suggested.



No, I don't have years or generations of experience to draw on. But it is up to you that do possess this to teach, encourage, critique (but not criticize), empower and pass on the knowledge and love that you have for "steam". Otherwise "the art" will surely die.



Everyone here has my personal email as I have made it publicly avaialble, if you would like to continue to receive and share data please contact me directly. I will no longer be sharing it publicly nor using it to invoke what I thought would be worthwhile and interesting discussions.



Good day.

David Nadle

Reconciliation

JP, you have fast vents on your rads. It's possible that with no main vents the increase in backpressure is small, and therefore the decrease is steam velocity is small. Without main vents the system balance may favor the furthest rads over the closest, somewhat emulating the function of main vents.



And that's the whole point of main vents. When the steam favors the mains before the rads a reserve of steam is available to all rads at the same time. And this lets you calculate vad renting based on their volume instead of their distance from the boiler.



I hope this concept helps you reconcile your data with theory and practice. And as far as not sharing your results publicly, I hope you'll reconsider and develop a thicker skin. All due respect, you did put a glass pipe in your wet return. You have to expect a little teasing.

Unknown

Misunderstanding

Okay- let’s back it up a bit.  I think we are all on different tracks here.

The title of this post  was  “Main Venting Doesn’t Matter ?!? “  I read the post and did a quick overlook of JPF’s data which I found very interesting. My thought was that this situation was quite like what Boiler Pro described in his article “Taking Another Look at Boiler Sizing Methods” , that is, the size of radiator venting has increased so much that when you sum up the total radiator venting capacity it far out numbers the capacity of the main vents.



  I don’t remember the exact phrase I used before my editing, but it was something like “You’re right, you don’t need main vents”.  In this phrase I was referring to solely to JPF’s data which show that in JPF’s system as it is configured, the main vents don’t seem to have that much effect on the system.  



Later I came back on line and read Mr. Gill’s post which I felt was in response to my comment, “You don’t need  main vents” and I then realized that my comment could also be taken in a general  context  of meaning  main vents aren’t necessary at all which we all know is absurd.  Further more I started thinking about how confused  I was when I first came on this board as a “newbie” and that if some one new to steam read my comment it would do them a great disservice by greatly confusing them.

  This concern, to avoid confusion, was my sole reason for editing my post. I probably should have made that more clear at the time I edited my post but my wife was waiting at the door for me to take her out to dinner so my reply was very brief.  I feel that Mr. Gill’s remarks as directed at my confusing comment, are very appropriate.  I would like to apologize to Mr. Gill and JPF for any misunderstanding and confusion that my inadvertent comment  may have caused and would hope that JPF would reconsider as I think we all find his contributions very interesting.

- Rod

gerry gill

I apologize for offending you (or youz as they say in Philly)

my concern is that a brand new person will stumble on this thread and get the thought in their head that they don't need main vents, and when they have exhausted all other resources they will call a pro to look at their issues and the pro will say lets start by getting the mains vented well, and the persons gonna say ''main vents aren't necessary, cause i saw it online''..see where i'm going with that..

jpf321

thanks Mr. Gill

thanks Mr. Gill, i appreciate you concerns and accept your apology ..



you and all newbies and anyone else should know that after last night's data, it looks like



correlating basically the same time period, with the same number of cycles, on an overnight of approx the same outdoor temp and changing nothing else... ON AVERAGE, RUNNING WITH VENTS SHAVED 3 MINUTES from the end of furthest rad measurement but lengthened my runs by 3mins ... 



i would appreciate someone duplicating my work on their own and affirming my results.



i will post the results in the $$$ thread (linked at top of this post)



trying to make sense of it:

   if, as someone suggested, the furthest rad would be favored by the lack of vents .. then the steam took a bit longer to get there .. and then backed up to the next rad down the line, which is the LR Couch rad which may have had an effect on the t-stat (shorter run) .. similar on the other main branch .. it would have favored And being the furthest and then Foy next far then DR which may affect t-stat (shorter run) .. I must admit that last night I physically felt warmer with the vents on.

  with the vents, all rads would have in theory favored equally (and got to furthest faster), and thus had less proximity effect on the t-stat leading to longer runs.

  in order to test this, I would have to run the same test on a middle rad on 2nd flr...to see if a mid rad timing changes, (or even gets heated all across)...tonight I will run WITH VENTS TESTING MID RAD MstB.

Mark N

main vents

Maybe not having main vents alters the distribution of steam in your system. Allowing the rad that in the room where tstat is to get more steam than it would normally get with the main vents in place.



MArk

Steve_210

is it possible

that your boiler is old and has a large water content and the main vents are not as critical as they would be with a new steamer, just a thought. 

jpf321

thanks Mark & sprinter

Sprinter -- yeah .. i have an old one .. maybe "acting" more like a coal unit than the newer ones ... i didn't get a chance to meet you the other night at Dan's .. I had wanted to say hi.



Mark - i think that's the same thoughts I'm having about it ..

Steve_210

i do not know

if this is correct i was just throwing it out there in the hope that some of the main steam guys like Gerry gill would chirp in. I have installed main vents for homeowners who SAY there was no differance. I think its easier to see the benifits on larger systems. just my experance so far.

jpf321

this begs the question ..

have you heard from other homeowners that rec'd main vents that there WAS a difference?

rcrit

Adding main vents helped me

I had no working main vents and my system wasn't working well at all. On my two mains there was a single, completly clogged Hoffman 75. Steamhead replaced itwith a Gorton #2 and added a Hoffman 75 on the shorter main and I definitely see a difference.



I'm in rather a unique position that my boiler is quite a bit undersized so some of my radiators were starving and not working at all prior to the new main vents. I did crazy things like removing vents completely from some radiators in an effort to direct steam to cold bedrooms. Even with the new mains I only have 1 out of 11 radiators that heats all the way across. I consider myself lucky if they heat 1/3 across.



I must say I prefer the Hoffman vents because it makes a nice clunk sound when it opens and closes, letting me know its working. The Gorton is quiet so I can't be sure if it is clogged again or simply quieter by design. I keep meaning to try to remove it and give it the blow test but can't seem to talk my wife into turning off the heat for a while for me to try :-)

Steamhead

And that

is why we need main vents. They give each radiator an equal shot at the steam. Thanks, Rob. 

gerry gill

but Sprinter, did you install ''enough'' main vents..

by that i mean i've noticed that a single main vent is about useless..but massive venting seems to make a difference..thats why i've been a fan of massive venting..we had a customer in a big mansion who paid 1500 dollars a month in gas..it took 18 minutes to get steam to the end of the main..it was a single loop main, down one side across the width and back to the boiler..typical coal configuration..we installed massive end of the main venting, and got steam around the loop in 8 minutes now..her gas bill went down to 800- 900 a month..thats big savings for 4 gorton # 2 vents..you can test this without the monetary expenditure just by removing the vent from the pipe..leave the pipe open, (just for the test obviuosly) and time it with an open pipe..then if its an improvement, install as many gorton 2 main vents as it takes to equal that open pipes time..hopefully its a 3/4'' tap pipe or bigger..then i think you'll notice a difference..i guess i see what your saying..i've noticed its either massive venting or its a waste.

Steamhead

We had one of these recently

where we changed the plugged pigtail, and the now-operational Vaporstat cut off the burner long before the steam reached the end of the main. We replaced the failed Dunham crossover trap with four Gorton #2 vents, and the steam rocketed around the long loop main before any pressure was built. Simple!



Most of our main venting jobs could be considered "massive" when compared with the amount of air they have to vent.

lutorm

I'm with you

Comments like that do not encourage discussion, which is what you ultimately learn from. I too have experienced similar responses from various online communities that seem to interpret questions as endless challenges to their authority. 



If you based on what you know come to a conclusion that is contrary to "conventional wisdom" and state so, that doesn't mean that you are saying "you are all wrong". It just means "based on this information I've come to this conclusion, and if the conclusion is wrong based on empirical data then please help me figure out where I went wrong." This sort of exchange happens everyday in my line of work (research), but apparently many people are not well equipped to handle it.



I'd encourage you to continue posting and not be discouraged by a few negative comments.