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main vent location

IGonzaIGonza Member Posts: 17

I have a question about the location of one of my main vents. I've attached the picture of its location. The steam comes from the left and there are 3 pipes go up to the radiators that are not on the picture. The pipes are 2" and about 41 feet long.
Does this vent work properly on that branch?

The problem I'm trying to solve is :
1. my boiler runs a few cycles to maintain the temperature. Every cycle the vent on radiator start to hiss and release some air (hot). Other vents stay closed including that Gorton on the picture.
2. after thermostat shut off the boiler, about 1 minute later, this vent and another vent on second floor, start to suck the air into the system.

I'm wondering if it's a problem with the main vent location/size or bad vents?

Thank you.


  • FredFred Member Posts: 7,261
    That's a Gorton #1. Is this the only Main? With a 41 ft. Main, I would put at lease a Gorton #2 on there. It has about three times the venting capacity of the Gorton #1. For my money, I'd install the Barnes and Jones Big Mouth. It costs the same as the Gorton #2 and has almost twice the capacity of the Gorton #2, 6X the capacity of the Gorton #1, it opens faster and is solid brass, great quality.
    If there are other Mains, and you do add venting capacity to this main, you may need to vent them differently, as well, to keep a balance of steam flow through each main.
  • IGonzaIGonza Member Posts: 17
    edited January 2018
    I have 2 main pipes. Another one goes to the ceiling and I cannot tell what size of the pipe it is. Second main vent is Jacobson self adjusted. It has pretty big hole on the top. On the second picture is the end of that main. That main has only 2 radiators on first floor and 2 more on second.

    My main concern was about the location of thee Gorton vent. This is a return line.. Is it possible that returning condensate makes it less efficient? And in general, that sucking air on radiators at the end of the heating is related to the main vent functionality?
    Also, is the faster main venting always the better?
    How to make the main vent to open before the vents on radiators?

  • nicholas bonham-carternicholas bonham-carter Member Posts: 7,607
    Both vents should be bigger, and the big mouth vent is a good choice, as far as its air elimination capacity. It does not have the internal float to control a rise in level of water in the wet to dry returns, and so if your pressure is too high, you may have water coming out. There are other reasons to have the pressure low as well. Put them on, and then if you need some pressure control, maybe a Vaporstat would be in order.
    The savings in burner time, and fuel consumption reduction will compensate for the expense of these items, (including a low pressure gauge, graduated in ounces), so that these additions are not an expense, but an investment.—NBC
  • IGonzaIGonza Member Posts: 17
    Nicolas, let me tell the whole story.
    We moved to this house a year ago and at that moment I knew nothing about steam heating.
    Since then I did some research. Thanks this forum exists.
    So I did a few upgrades:
    1. I found hidden leaking return pipe and fix it.
    2. I found that my pressure is more than 3psi. So I installed second gauge 0-2.5 psi and confirm it. This was even with the lowest settings on pressuretrol.
    3. I bought vaporstat and installed it in sequential order with existing pressuretrol. During this change I decided to check the pigtail. It was completely blocked. Probably the running pressure was even higher. So I cleaned pigtail and now I have 2 gauges , pressuretrol and vaporstat on it. You can see it on second picture.

    The changes in the boiler work is significant. But I'm not sure these changes are good.

    Before: boiler was running about 30 mins until pressuretrol stops it on high pressure. Then thermostat stops it. So it was 1 long run to maintain the temperature.

    Now: 15 mins to boll the water. Stops at 11 inches, in 1 minute restarts at 6 inches. 1-2 minutes run to build 11inches again. It cycles several times before thermostat stops it. Then 10-15 minutes to restart again , depends on the weather. And it's the coldest time in New York / New Jersey area.

    Do the short cycles mean oversized boiler?

  • nicholas bonham-carternicholas bonham-carter Member Posts: 7,607
    Your boiler may be oversized, and it is hard to correct that, however, you can let the air out as quickly as possible, using larger main vents. This will fill all the supply pipes first, before the steam begins to rise up to all the radiators simultaneously, making an even heating in all rooms.
    Once the venting has been improved, and you have a short cycle, before satisfying the thermostat, then you could raise up the upper limit of the vaporstat a little bit.
    Later on, in between mowing the grass in the summer, you could consult someone about reducing the output of the burner, if you are oversized.
    Like you, we have all learned so much from this website, and the professionals who are here helping.—NBC
  • New England SteamWorksNew England SteamWorks Member Posts: 1,173
    The locations are fine. It' the size that is the problem. You'll see a big difference with a couple of Big Mouths. That's your next step. Are all your pipes insulated?

    New England SteamWorks
    Service, Installation, & Restoration of Steam Heating Systems
  • IGonzaIGonza Member Posts: 17
    Thank you for your responses.
    I will install 2 bigger vents first and check if it changes something. I believe it will not reduce short cycles, but at least the venting should be better.

    I insulated 1 main pipe as on the picture (about 95% of it). Second main and all the pipes to the radiators are hidden in the walls and it's hard to find out without opening. I believe they are not insulated. Second main is somewhere between the basement ceiling and the first floor. It's probably not enough space for insulation. I will try to find out how to open part of the ceiling and check it.

    Also, I saw many times on the forum it's good to calculate total EDR for all radiators. Is there any instruction how to find it for each radiator?

    Thank you
  • BobCBobC Member Posts: 4,882
    This should help .


    Smith G8-3 with EZ Gas @ 90,000 BTU, Single pipe steam
    Vaporstat with a 12oz cut-out and 4oz cut-in
    3PSI gauge
  • IGonzaIGonza Member Posts: 17
    edited January 2018
    Almost all my radiators look like on the picture.
    What kind of radiator is it? it's about 20" height, 31.5" width and about 5" depth.

  • IGonzaIGonza Member Posts: 17
    I think I found that looks similar to mine and the dimensions are the same.

    Am I correct this is 31.5 EDR?

  • IGonzaIGonza Member Posts: 17
    Ok, at last I did EDR calculations and this is what I've got :

    Total 246 EDR. 135 for Main 1 and 111 for Main 2.

    This is what my burner says:

    if I understand correctly it provides 325sq ft.
    If my calculations are correct it's 33% than I need.

    Is this enough to be considered oversized?
    If so, will it be still oversized if I add another radiator with 36 EDR? 325/(246+36) = 1.15 => 15% still more than needed.

    Thank you
  • FredFred Member Posts: 7,261
    Yes, 33% is over-sized. Actually anything over the connected EDR, give or take a few Sq. Ft. of steam is over-sized. Adding more radiation, if you need it, will certainly help narrow the sizing issue but having the boiler down-fired a bit will also.
  • IGonzaIGonza Member Posts: 17
    I saw a few discussion on the forum if the 33% should be added to the top of boiler capacity or it's already added. So I was not sure about it. Thank you for confirming this.

    Also, I saw a few threads people said stay away from down-firing the boiler. So I assumed it's not recommended.
    From my understanding, I believe that removing only the burner (my boiler has 5) will not help, but only increase the time to boil the water. So the section of water should be also removed? Is it possible and save?
  • FredFred Member Posts: 7,261
    The 33% Pick-up factor is on top of the Sq. Ft. Steam rating on the boiler plate. Down-firing is fine if it is done by a professional and he/she has the proper combustion analysis equipment to make sure it it done right. It is not something a homeowner should attempt.
    You typically don't want to take a burner tube out or a section of the boiler block, especially on an older boiler. Just leads to other issues worse than being over-sized.
  • IGonzaIGonza Member Posts: 17
    Ok, so my plan is to replace 2 main vents with Barnes and Jones Big Mouth vents.
    And after heating season is done, I will talk to someone about down-firing.
    Thank you for all your help.
  • FredFred Member Posts: 7,261
    Sounds like a Plan.
  • ShalomShalom Member Posts: 115
    Technically that's not a radiator, it's a convector.

    Also, shouldn't that air vent be in the lower opening, half way up? That top tapping is there for a bleeder valve if you're using the convector for a hot water system.
  • IGonzaIGonza Member Posts: 17
    Shalom, honestly I never paid attention on the vent location.

    I have 6 radiators (convectors) like that one. 4 of them have the vent right in the middle height of the unit. 2 of them are like on the picture. Those units are in the bedrooms, and I don't have any problems with them. They work just fine as others.
    Why should it make a difference?
  • ShalomShalom Member Posts: 115
    Only difference I can think it would make, is that if the vent is right at the top, you wind up with more air and less steam in the radiator when it shuts off. I don't actually know if it matters with a convector, because a lot of the heat transfer comes from the top of the unit anyway (air enters the bottom, warmed by the fins, wafts out the top).

    As long as they're heating evenly and aren't cold halfway down, I don't see that you'd need to change it, especially if the plug in the lower tapping has been there for decades and has lots of paint on it. Probably be more of a pain in the neck than it's worth to swap them. It's just not the way it "should" be.
  • IGonzaIGonza Member Posts: 17
    Fred said:

    The 33% Pick-up factor is on top of the Sq. Ft. Steam rating on the boiler plate. Down-firing is fine if it is done by a professional and he/she has the proper combustion analysis equipment to make sure it it done right. It is not something a homeowner should attempt.
    You typically don't want to take a burner tube out or a section of the boiler block, especially on an older boiler. Just leads to other issues worse than being over-sized.

    I was thinking about the fact, that down-firing will lead to slower way to get the water to the boiling point.. So I thought why not to use full capacity of the boiler to get some pressure in the system and then switch to low gas flow... I found there are some 2-stage gas valves on the market that can serve this scenario...
    The question is : Is this solution better than just down-firing?
  • FredFred Member Posts: 7,261
    Either down firing or a two stage gas valve will serve your purpose. You can typically down fire 15% to 20% and not have the expense of a new two stage gas valve and the a vaporstat to control it but they do work well when properly set up. As far as down firing, after the initial boiling of the water and given that most newer boilers don't have the large volumes of water that the older ones had, I suspect down firing will also work well. Typically the water hasn't cooled down that much between calls for heat. At least not during the colder part of the heating season.
  • IGonzaIGonza Member Posts: 17
    The problem I'm trying to fix is short cycling on pressure after all vent are closed. I don't have any problem with the temperature at home. And after I changed the vents on radiators and on mains, it works much quiet than it did before.
    So it becomes my hobby to play with the steam boiler rather than an attempt to fix something real...

    I'm trying to understand the following statement.
    Down firing more than 15-20% is not allowed because of :
    1. not enough combustion
    2. initial boiling will take a long time (not a stopper)

    But with 2-stage valve I can down fire for more than 50% (I've seen this somewhere on the forum). Why is there no problem with combustion if I use 2-stage valve?

    Second thing is: why do I need to replace the part of the boiler to down fire it and not just partially close the manual gas supply valve (with all precautions and safety checks)?

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