Main air vent location


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Old 11-19-08, 12:38 PM
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Main air vent location

I have a 1 pipe steam system. There was no main air vent installed, I think it was plugged. Last year, I have a plumber installed a Gorton 1 main air vent where it was plugged as seen here:


Here is the main pipe:


This is the end of the main pipe and then curve to the left to a raditor and then pic 1. There are 3 risers that feed 2 raditors in the first floor and 4 in the second floor.

My question is, by having the main air vent there at the return, does it serve any purpose? I haven't really noticed. Also, will adding another Gorton 1 with a tee there will help? I have a water hammer problem in my master bedroom. I hear the loud bang once the thermostat reaches the set temp or boiler stop firing. Air vent is changed, radiator is pitched, valve is fully open. Also, my bathroom vent and third bedroom hisses loudly.

A few days ago, I put in Squick to clean the boiler. I haven't drain it out yet. The water glass gauge is filled half way. Water only move at most 3/4" when the boiler is on.

Any ideas what else to check for?
 
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Old 11-19-08, 05:24 PM
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Check out the link below. A second vent will help vent but not do anything for the noise. The noise is due to water in the horizontal main. Insulate the mains.
Steam FAQ
Also see other steam pages.
 
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Old 11-19-08, 05:49 PM
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Its been a while, but here is my 2 cents worth. If I am not mistaken, you want a main vent on the return end of any main line there is, so if you have a split zone, you would need two vents, one on each return. That is to make sure the mains are evenly filled with steam and ready to send steam to any branch radiator line.

Banging is caused by steam hitting water someplace, and hissing is acceptable as long as it stops as soon as the steam gets there. It should not blow out moisture. You may here that one more because of the setting the radiator steam vent is set at, which is derived by how far away and how fast you want a certain radiator to heat.

A 3/4" fluctuation in the gauge glass is good.
 
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Old 11-19-08, 07:16 PM
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rbeck: Thanks for the link. Looks like I have a wet return setup. From the main vent, that pipe runs for another 5-6' and then drop to the floor level for another 25' back to the boiler. What do I need to buy if I want to insulate the main?

plumbingods: I only have 1 main line. The bathroom radiator usually hiss for a few minutes and then stop when the boiler is firing. The third bedroom, it never hiss before with an old small vent. Since I changed to a larger vent, it hiss continueously as long as the boiler is firing. None of them blow out moisture though. Also, all the radiators get hot around the same time.

Question, not sure if this is normal or not. The boiler is Weil McLain EG45. The last couple of days have been cold in NYC. Outside temp is in the 30's with wind chill in the mid 20's. It took the boiler about 70 minutes to heat from 60 to 67 in a cold start. The boiler would fire up for about 20-25 minutes and then stop. It will fire up again in a few minutes for several minutes and then off once it reaches about 2.5 psi. This will repeat until the set temp is satisified at the stat. The stat is set to 2 cph. Last year, I had it at 1 cph but the temp swing was too much. Is this normal?

Here is a pic of the boiler (the pressure relief valve is piped down but not shown in pic):
 
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Old 11-19-08, 07:33 PM
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That does not seem to strange to me considering all the UN-insulated steam piping I see in these pictures. It is criticle to insulate those pipes. You will need to use fiberglass, as rubber will just melt. Talk about a waste of heat.

Does that radiator that hisses all the time ever heat up? If ye and you see no steam coming from it, leave it alone, but I am willing to bet is either not open enough and not heating properly or is a defective valve.

I stumbled on this yesterday, and after looking at your picture of your boiler, you may want to check this out. It is a recall for that vent damper you have. Picture looks exact. Here is the link

Gas Vent Dampers Recalled by Effikal Due to Carbon Monoxide Hazard
 
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Old 11-19-08, 07:53 PM
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It heats up quite fast and quite hot. With the old small vent, it would not hiss and would not heat up as quick but it does get hot. Very strange.

Just checked my serial number. It's in the 3047xxx range so it's not part of the recall.

btw, will it benefit to add another Gorton 1 main vent by using a tee?
 
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Old 11-19-08, 07:59 PM
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I dont think so, but I would need to dust off some old steam install books to answer correctly, but first I need to find them

If that radiator heats up fast, try closing down the adjustment on steam vent or replace it with a smaller valve. If it still hisses all the time, I think the valve is junk.
 
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Old 11-19-08, 08:07 PM
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A good check to see if it would make sense to add a second vent. Start with cold pipes. Start the boiler and when the steam starts moving out of the boiler time how long it takes to get steam to the vent. Do the same thing with no vent in the pipe. If it gets there considerably faster it can use a second vent on a tee.
 
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Old 11-19-08, 08:11 PM
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I ordered some Gorton air vents from Pexsupply haven't ship yet. It should be better than the cheap no brand ones I have now. Maybe that will fix the hissing.

Thanks for the help.
 
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Old 11-19-08, 08:37 PM
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Fiberglass insulation, copper tubing insulation, fiberglass pipe insulation

Is this insulation good? What thickness do I need? 1/3 of the main pipe distance is in the garage and that is the part I want to insulate first.
 
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Old 11-19-08, 10:50 PM
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I was trying to find something to answer that properly, but was unable at this time. I personally would go with no less than 1" thick, especially in the garage area. Make sure to but all lengths together and tape them with proper tape. The best way to insulate the fittings is with insulation fitting covers stuffed with loose insulation, but I am sure a more economical way that will not look as pretty can be designed.

This is why your boiler short cycles. Steam cools of quite quickly when open to the elements, ie: no insulation.
 
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Old 11-20-08, 07:24 AM
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I don't care about pretty in the garage. Can I just use duct tape instead?
 
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Old 11-20-08, 07:59 AM
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sure, but when you buy the insulation, they should give you ( you may need to ask, but it is free),some tape strips for all the butt joints, and just cut the insulation at 45* angles at fittings to get insulation coverage on them.
 
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Old 11-20-08, 08:53 AM
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I ordered the 1 1/2" Knauf insulation from Express Insulation. Didn't want to risk 2" because the pipe is pretty close to the wall in the garage. Let see if this will cut down on the short cycling and possibly the water hammer.

Thanks again.
 
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Old 11-20-08, 09:34 AM
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I was thinking about the water hammer thing also, with less quick condensation, there will be less water in the lines to mix with steam.
 
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Old 11-25-08, 09:10 AM
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I replaced the bedrooms and bathroom with Gorton D vents. Now the hissing is gone except the bathroom with a minimum hiss noise. Hopefully if I have time, I drop by the plumbing store and pick up a tee to install the second Gorton 1 vent in the main.

Insulation still haven't arrive yet though.
 
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Old 11-30-08, 09:44 AM
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Added the second Gorton 1 vent to the main and insulated the 15' of pipe in the garage. The water hammer is still there.

Any more ideas? This happen after the boiler cycle in the master bedroom.
 
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Old 11-30-08, 09:51 AM
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Is all the steam piping insulated now or just pieces?

Do you see any pipes pitching the wrong way, causing a water pocket? Use a level.

Has anything changed so far?
 
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Old 11-30-08, 10:12 AM
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The pipe above the boiler is insulated, not shown in the pic. The pipe then run thru the garage. It's about 15' of pipe. That is the part where I have it insulated. btw, my basement is not really a basement, it's almost on ground level, just like most of the brick row houses in Brooklyn.

The water hammer have always exist in the master bedroom since I bought the house last August. As far as I can tell, the radiator is pitched correctly. Also, I have a plumber confirm it's OK last year when I got the annual service.
 
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Old 11-30-08, 10:16 AM
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btw, is it possible the boiler is way oversized? That is why it's short cycling. Putting all the 3 floors together, it's about 1700sq ft. A Weil McLain EG45 boiler is installed. It's a 150k BTU boiler.
 
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Old 11-30-08, 12:54 PM
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OK, first off

I think your boiler is way oversized, but I have never actually sized a steam boiler and only size by BTU and not by sq ft of steam.

With a well insulated house the BTU's are not going to be more than about 60,000. But most old steam boiler houses are not insulated very well, so that is a major issue in properly sizing the boiler.

With steam boilers, ALL piping must be well insulated with steam ppipe insulation or the steam will condense too fast causing extra liquids in the system along with short cycling. I have only serviced 20-40 steam systems and installed possibly 10 in my 25 year heating career. I am not an expert but have a good knowledge of reidential steam.

I don't know much else to tell you at this point.
Clean water in boiler
Hartford loop
Pitched piping and radiators
INSULATED pipes
Properly sized boiler (check with SlantFin.com for a FREE heat loss program to size your system
Cleaned boiler
Steam vents working properly.

Steam is actually the easiest heat available, but can be tricky at times.
 
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Old 11-30-08, 05:45 PM
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Thanks for the help anyway. Maybe when I have time, I will check out the slantfin.com site. If it's way oversize, I will hire a plumber to reduce the firing in the boiler.
 
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Old 12-03-08, 01:30 PM
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First let me say that I'm not a heating professional - just a homeowner with a one-pipe system that's familiarized himself with the fundamentals of residential steam heat. Once you learn the few simple rules of thumb, you'll be able to understand and maintain your system

I can't see clearly from the picture, but the near-boiler piping looks like it may be incorrect. The header (the horizontal pipe that's connected to the vertical pipes coming out of the boiler should be at least 24" above the waterline (center of the sight glass). Also, the riser from the header to the main should not be between the risers from the boiler. If your boiler has these 2 conditions, then it will be sending a lot of water up the pipes and you'll never get rid of the water hammer. I've included a link to the Weil-Mclain installation manual for your boiler below. It shows how to properly hook up the piping, and failure to do it correctly will result in a host of issues, including higher than necessary fuel bills.


Regarding the boiler size - Steam boilers only see the radiators (they are the connected load). The outside temperature and the heat loss through your walls are irrelevant to sizing the boiler, and only determine how frequently the system will operate. Go here Radiator Sizing Guide for information on calculating how many Btu's of radiation for all your radiators. The boiler should be sized to the total radiation of all the radiators plus 33% to account for the mass of the supply piping. If the boiler is too small you'll never make enough steam to heat all the radiators on the coldest days. Too big and it will short cycle because it produces steam too quickly, which raises the pressure quickly, which trips the pressuretrol and shuts off the boiler. Wet steam is also a condition of over-sizing the boiler. The Weil-Mclain web site gives the specs for your boiler in this document. http://www.weil-mclain.com/downloads...ilermanual.pdf. Your boiler has a net rating of 94,000 BTU steam or 392 square foot EDR. These values already include the 33% pick-up factor for the piping. That sounds about right for a 1700 sq. ft. house built during the steam era, so my guess is that the boiler is sized reasonably and it's either poor near-boiler plumbing and/or uninsulated pipes that are causing your problems. I also recommend that you visit HeatingHelp.com and purchase one of these books on steam systems. You can also post for help on their forum - there are real steam experts that will respond to your questions.

regards, Steve
 
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Old 12-03-08, 02:38 PM
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Yes thats an extremely low header, looks like there was room for taller risors.
In addition the elbow at the end of the header with the equalization pipe connected into the heel is incorrect and trapping condensate.
It may be an optical illusion but it appears the header is reduced after the risor.
I would repipe it and consider doing a drop header which will assist the piping at the boiler and keep the majority of the condensed steam back at the boiler
 
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Old 12-03-08, 03:00 PM
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Thanks Steve,

It seems as though you may have a little more or different knowledge of steam than I do. As I said, I have repaired or replaced steam boilers, but never designed any installs. When I looked at the pictures supplied, I did not notice the tee between the two supplies until I looked closer after you mentioned it and I agree with that statement.

On the other hand, I have never been told about the 24" min for the header from the water level, and I just thought of a boiler I helped someone replace 15 years ago and when we did, we kept having surging problems. Probably because there might not have been enough space between the header and the water level.

The reason I said the boiler was too large was because he said it was 150k btu. I understand steam boilers are sized by the radiators, but the radiators are sized/designed by the BTU heat loss of the home, correct.

Thanks for posting those links, as I am still interested in understanding steam a little more. I may be supervising a Geo-thermal heating crew soon and you never know if I will get a service call from some other heating systems of which I have been doing for many years, and it would be nice if I knew more than the help did.

Mark Beer 4U2Beer 4U2
 
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Old 12-03-08, 03:32 PM
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24" guidline comes from a field rule that for every 18" of rise between operating water line and inside bottom of header is allowed 1 PSI of operation. Thus 24" will allow a max 1.25PSI max operating pressure, well above any residential non-vacuum system.

Exceeding this and water from the boiler starts pushing out the return causing inefficient returning condensate, flashing, surging, floding and a few other possibilities.

And yes the heat takeoff must be off the end after risers, before equalization drop otherwise the swirling steam in opposite directions are fighting at the T
 
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Old 12-03-08, 04:15 PM
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plumbingods,

The person that sized the radiators should have done it based on a heat-loss calculation, but at this point in time the system is stuck with the installed EDR. What I've read is that in the old days, people were paranoid about air quality and would keep a window open all night, so the radiators were matched to a much higher heat loss than we would use today. Also, many old houses have been insulated, and/or have upgraded windows, so most often the radiating capacity of old steam systems is higher than it needs to be. But in replacing an old boiler, the new boiler should be matched to the radiators or the system won't run efficiently.


ZL700,

In a one-pipe system, there is also another critical value called the "A" dimension that I think you might be confusing with the min. header distance. The "A" dimension is the minimum differential between the water line and the lowest point in the dry return(usually the end of the main), and should be not less than ~28'. 28" of water is equal to ~1psi, and a properly designed residential steam system will never have more than one psi drop across it, so 28" ensures enough headroom to guarantee that the water will never spill into the main. The water will rise in that leg because the steam pressure at the end of the dry return will be lower (pressure drop across the length of the main) than the steam pressure at the top of the equalizer.

BTW, the A dimension will vary with the BTU output and system operating pressure, but for residential systems 28" ensures that you'll never have a problem (unless the wet leg gets plugged and then the pressure balancing stops working).

It's my understanding that the min 24" header elevation is there to compensate for the fact that modern boilers have a very small steam chamber and rely on properly designed/installed near boiler piping to separate the steam from the water.
 

Last edited by Steve Raft; 12-03-08 at 04:51 PM.
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Old 12-03-08, 05:06 PM
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zuffy,

I don't want you to think that I hijacked you post and turned it into a theoretical discussion on steam systems.

I wanted to point out another problem that I see in your system. The take-offs for the radiator feeds are not piped properly. They should be coming off the main at a 45 degree angle, not vertically off the top of the main. In this configuration, the condensate returning to the main is dropping right onto the fast moving steam which results in two bad things: It robs BTUs from the steam, and it can also get swept along and carried back out to the system instead of returning to the boiler.

PS, I wholeheartedly agree with plumbingods - get it all insulated - it should help.

Steve
 

Last edited by Steve Raft; 12-03-08 at 05:22 PM.
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Old 12-03-08, 07:11 PM
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Thanks again steve,

I agree and understand what you are saying about the sizing, very well put. Also remember, that when steam boilers were installed regularly, a lot of these boilers were coal boilers converted to oil, or soft flame burners where they could care less how much oil it burned as long as it heated the house. Now we have energy crisis' in this country and people actually care about their oil/gas consumption. Or is it just their wallet? I think you understand.

Mark
 
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Old 12-03-08, 09:00 PM
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Steve,

Thanks for the post. There is nothing I can do about the take off feeds. Any fix would mean a gut renovation. The house is expensive as hell already here in Brooklyn, NY. It's late now and I will reread your posts tomorrow so I understand the pipping you're talking about at the boiler level. And I will take some new pics at different angle to help out.

btw, I did posted in heatinghelp.com. Didn't get much help. I got the book too from last year.
 
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Old 12-04-08, 06:30 AM
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All so Right steve, and Dan would be proud
 
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Old 12-04-08, 08:54 AM
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Damn! This thread rocks. Kudos gentlemen.
 
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Old 12-04-08, 07:23 PM
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Pic of the boiler. Boiler is sitting on top of a 1.75" concrete. From the concrete to the middle of the glass tube, it's 24". From the middle of the glass tube to the bottom of the header is 16"



Back of the boiler



The pipping
 
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Old 12-04-08, 07:53 PM
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Old 12-05-08, 07:58 AM
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OK, so it looks like the riser is in the wrong place on the header and the header does not meet the 24" minimum.

I have no plan of redoing the pipes now but maybe later when there is extra fund. Any rough estimate what it might cost for a plumber to repipe it in NYC?
 
 

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