Study: Energy Savings using Main Vents

Shaun McDonnell

<span>Hey Everyone, I'm new to the site, new home owner and new to steam heat so I have a lot to learn.  I've been using the site to try and educate myself about the system and how to balance it out and maintain it with winter on the way. I've already ordered Dan's book The Lost Art of Steam Heating and picked up 51' of fiberglass insulation that is missing from my system. I came across this study about the use of main vents. It was a good read and I wasn't able to find it on the site yet so I thought I would add it.  </span>

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<span><a href="http://www.osti.gov/scitech/servlets/purl/10191625">http://www.osti.gov/scitech/servlets/purl/10191625</a></span>

nicholas bonham-carter

Government study using low income residents

Thank you very much for your contribution!

It's lucky the Government did not want to study "the effects of prolonged exposure to Co", or somesuch!

If you have a good low-pressure gauge (gauge store.com-03 psi), you can see the effects of poor main venting, as the system pressure rises to squeeeeze the air out of the constipated little radiator vents. This enriches the fuel supplier, and causes those furthest from the boiler to wait longer for steam, so while you are wrapping your pipes, check your main vents, and the pitch of the pipes before they get covered up,--NBC

Shaun McDonnell

thank you

I’ll definitely be able to check the pitch of the pipes before get the insulation in, that is a good call. I actually don’t have any vents on the main right now and I’m not sure it is in the cards for me to do this year.  The system has four radiators and one of the four has a return line on it (making it a 2 pipe system I’m thinking). It looks like it was added with the addition of a bedroom back in the 50’s. The remaining three radiators are part of the one pipe system. The return line is at the farthest end of the main from the boiler so I’m not sure if that is where the vent was and they removed it to put in the return line or if that replaces the need for a vent but like I said I’m still wrapping my head around it.  We’ve been in the house for 2 weeks so trying to learn fast but still be accurate, I have to stare at it for a while.

Rod

Venting

Hi Shaun- Welcome to the "Wall"!   I guess the first question to ask is how well is your system working at this time and what do you think needs improvement? 

   On a one pipe residential steam system there are two types of air vents - Main and Radiator vents. Main vents are high capacity vents which allow air to escape quickly from the steam main but close when steam reaches them to keep the steam in the main.  Radiator vents vent air from the radiators but close when either steam or water reaches them.

While using a large capacity vents on mains doesn’t cause a problem, if you use too large a capacity vent on a radiator it can cause problems with balance and operation. There is an old adage- “Vent your mains quickly and your radiators slowly!”



When main vents are missing on the system, the radiator vents have to vent both the steam mains AND the radiators. This as you can imagine slows up the operation of the system so that typically a “knuckle head” tries to cure this problem by replacing the proper sized radiator vents with vent of much higher capacity. As mentioned above high capacity vents can cause problems.

Your system needs main vents!!!



   I’ve attached a blurb on venting which I wrote to answer the questions another homeowner asked me. I would also suggest you visit Gerry Gill’s website:  http://www.gwgillplumbingandheating.com/

Gerry Gill is a very experienced Cleveland steam pro. He has a lot of great info on steam heating on his website and is also the co author of the BOOK on venting steam systems.

http://www.heatinghelp.com/products/Steam-Heating-Books/25/146/Balancing-Steam-Systems-Using-a-Vent-Capacity-Chart-by-Gerry-Gill-and-Steve-Pajek

These venting book tables are also included in Dan’s book, “Greening Steam”

    You might also take a look at what is known as "off the Wall" in the Systems and Resources section at the top of this webpage as there is a lot of good information there.

- Rod

Shaun McDonnell

More to Come

Thanks Rod for all that info.

Right now the 2 farthest radiators we have didn't get hot when I took everything for a test run the other day. The farthest one is probabably a 15-20 foot run off the main to our bedroom and the other is about 9 feet off the main. The iron tubing was replaced with 1 1/4" copper during some renovation and has no insuation on them at this time.  The one in the bedroom is probably the largest one in the house if it isn't it is close to it. I could hear air pushing out of the vent for a long time with no heat. That is probably my biggest concern at this time. I'll get some actual measurments and pictures on this post when I have a chance later this evening when I have them with me.

Shaun McDonnell

More Info

Okay, I gathered some more info and a picture of the end of the main line where the return line for the 4th radiator and the lack of a main vent. The 4th radiator is the only one on the system that uses a 2 pipe system. The picture shows both the steam line off the main and the condensing line that is connected. If there is any other info I can gather I'll be happy to grab what I can. I did look at the vents on the radiators but there is nothing on them with sizing or names they look pretty old. I also included a rough drawing if they system hopefully it helps a little

JStar

Radiator

That copper line is all wrong. Not only because it's copper, which will destroy the steel in the system, but it is piped incorrectly. It will fill up with condensate and never let steam through. It needs to look like all of the other radiator run-outs.

nicholas bonham-carter

2-pipe end radiator

It would be better to have that return piped in iron pipe, but since it is there, I would just make it work. Since it is only dealing with the condensate, it should be large enough. Is there a vent on the radiator? This may be one of the few situations where I would try a Gorton D, or other large vent, to see if steam can arrive more quickly.

The only question I have is: should the return line drop to the floor, and then go back to the wet return?-NBC

Shaun McDonnell

Size Matters

Hey Nick, there is vent on that radiator it has a very slow output on it is seems  but like everyone says vent the radiators slow but this might be to slow.

 

To answer what I can on your question:

I'm not sure if it should do that but at this time it doesn't. Right now the return line is a separate run back to the boiler.

Rod

Labeled Photo

Hi Shaun-  Attached is your photo with labels added. Do the Main and Retrun slope in the direction indicated?  What radiators are pipe "X" and pipe"Y" attached? What size is the copper pipe "X" ?

- Rod

JStar

Rad

Right now, steam will enter the radiator through the supply and return. The pressure in the radiator is equalized, and steam has no reason to go into the radiator. The return should drop down to the floor and then enter the bottom of the main, or a nearby wet return.

nicholas bonham-carter

2-pipe radiator on 1-pioe system

Rod, don't forget to label the supply for that rad on the backside of the Tee.

Steam enters the radiator through that take off, and the condensate will return through the copper pipe. I know we are against copper piping, but it's there and maybe will work. I think the cold radiator problem is a venting problem, and if the air can leave the radiator quickly enough, the steam will arrive quickly, and the condensate will flow down into the copper pipe into the dry return. Good main venting would be helpful here.

This piping arrangement reminds me of the steam pipe which has to cross a beam. In that the pipe is split, and goes above and below the beam, with the High road taking the steam, and the low pipe handling the condensate.--NBC

JStar

Rad

Quick and easy test:



Close the supply valve on the radiator, allowing the copper return to act like the supply. If it heats, it's the piping. If it doesn't, it's venting.

JStar

Vents

Bringing this thread back on track:



I speed-read the article. I saw no mention of the boiler sizes being correct, pressure settings, condition of radiator vents, any correction for DHW production which would lower cold-start times, steam leaks which will act like vents, or windows being opened or closed.



Too many variables to be anywhere near conclusive. We see a reduction in fuel usage everyday in residential systems.

Rod

Piping

Hi Guys- I'm familiar with what a loop seal is. I just wanted double check and positively identify Pipe "X" and Pipe "Y" in the photo.

- Rod

Shaun McDonnell

Pipes

Hey Rod,

Pipe X is actually 1/4" copper and pipe Y is 1 1 1/2" iron for about 3 feet after you see it enter the crawl space then it turn to 1 1/4" copper.

Shaun McDonnell

More Detail Coming

I'm actually working on getting a lot more detail to post on the Wall, I started gathering the radiator ERD, pictures, pipe dimentions etc that Rod suggested getting. I should have it up by tonight or Sunday. To keep this tread on topic I'll start a new one when I do and edit the link into this post.



Thanks to everyone for thier insight on this it is greatly appreciated.



Shaun

Shaun McDonnell

Moved to new thread:

http://www.heatinghelp.com/forum-thread/147220/Gen-Ed-101/success