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Do I need to revisit venting after new boiler replacement?

Kjmass1
Kjmass1 Member Posts: 266

Recently replaced my boiler with an EG40 with dual riser and drop headers, things have been perfect so far with temps in the 20s or so but as we approached a couple nights around 6-10F lows, and with almost 45-60 minute long cycles due to boiler being much smaller, a couple of the radiators closest to the boiler are now the fastest escape and are way overshooting, even with small vents. This short main has 2x Gorton 1 air eliminators, and have been hissing at a bit under less than 1psi. The other longer main has 2x Gorton 2s (the big ones), and we even have a radiator off that branch not getting any heat now. So smaller boiler (correctly sized and installed), now dry steam with drop header, what should I be looking in to?


Vaporstat is installed but set to 2psi.

Again, all seemed well outside of a couple of these design day lows.

Is this a main venting issue, radiator venting, or pressure setting?

Comments

  • pecmsg
    pecmsg Member Posts: 5,330

    got a picture of this vaporstat?

    CLamb
  • ChrisJ
    ChrisJ Member Posts: 16,319

    The longer the boiler runs the less control venting gives you because the slow radiators have time to catch up.

    At one point all radiators will spend most of their time full and venting will give you zero control over balancing.


    This is why more cycles per hour and TRVs are such a magical combination. Even without TRV's more cycles will help greatly.

    Single pipe 392sqft system with an EG-40 rated for 325sqft and it's silent and balanced at all times.

    ethicalpaul
  • Kjmass1
    Kjmass1 Member Posts: 266

    I have it set to a tight .5F differential, yellow line is the master where it starts to take off. So do I need to think about using the vaporstat cycle on pressure to get more CPH?

  • Jamie Hall
    Jamie Hall Member Posts: 24,984

    First off — vapourstat is set higher than it needs to be, and that may be causing longer cycles than you need. Try setting it to 1 psig cutout and 8 ouches differential.

    Now. @ChrisJ 's point is exactly correct, and is a very often misunderstood — if not completely overlooked — characteristic of one pipe steam systems. They must cycle if they are dependent on venting variations (which they almost all are) or TRVents for control. The cycling must have a long enough "off" phase for the pressure to drop to zero — usually a minute or so off is adequate. Ten minutes on is long enough.

    Much has been said over the years about the nuisance of the Cyclegard low water cutout cycling It's not a bug, it's a feature. That cycling, which is there to check for foaming, also serves to provide the needed cycling for one pipe steam control.

    If that is not the approach used, setting the cutout pressure as low as can be consistent with all the radiators being able to fill is about the best that can be done.

    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
    dopey27177Long Beach Edethicalpaul
  • Kjmass1
    Kjmass1 Member Posts: 266

    I haven’t seen it hit over 1psi yet, will the vaporstat even turn it off if it is set at 1?

  • Jamie Hall
    Jamie Hall Member Posts: 24,984

    If the pressure is staying low like that — first, congratulations the boiler is sized right! — and second, don't worry about the vaporstat. Leave it be.

    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • KarlW
    KarlW Member Posts: 156
    edited December 23

    If you haven't seen over 1psi, it likely means that your boiler is (likely) appropriately sized and filling the system without overfilling it. I'd find it hard to believe it is a pressure issue.

  • Kjmass1
    Kjmass1 Member Posts: 266

    ok…so how do I push steam where I need it then?

  • dopey27177
    dopey27177 Member Posts: 908

    Best set up is to lower your steam pressure as stated by chris and Jamie hall.

    As stated set at 1 PSI with 1/2 psi differential.

    Also you are over vented.

    Enclosed is a chart on Gorton vent valves.

    you will need to use smaller vent valves on your steam mains. I recommend

    using only one #1 vent on the main with two # 2 vents.

    on the over heatind radiators install smaller vent valves, this will cause those radiators to heat up a bit slower.

    Jake

    Long Beach Ed
  • mattmich
    mattmich Member Posts: 132
    edited 2:23PM

    » Also you are over vented.

    Is there general agreement that it is not possible to over-vent a main?

    And if there isn't, I'd like to understand. It seems to me that the first goal should be to fill the main with steam so that all radiators get a bite at the apple around the same time.

    On my system, it's not the venting that determines how fast the main gets filled, it's how fast the steam can heat the metal. Now I've insulated the new piping it's six minutes from when steam comes up to the main vents closing. It was 10 minutes before.

    cheers -m

  • ChrisJ
    ChrisJ Member Posts: 16,319

    I didn't say anything about pressure, and they're not over vented.

    Single pipe 392sqft system with an EG-40 rated for 325sqft and it's silent and balanced at all times.

  • Kjmass1
    Kjmass1 Member Posts: 266

    I didn’t think it was possible to over vent a main, I could see the ratio between the 2 mains being an issue. One is 20’ the other is 40’.

  • ChrisJ
    ChrisJ Member Posts: 16,319

    What are you using for a thermostat?

    Can you force it to do more cycles in a time frame rather than the temp diff?

    Single pipe 392sqft system with an EG-40 rated for 325sqft and it's silent and balanced at all times.

  • Kjmass1
    Kjmass1 Member Posts: 266

    Ecobee doesn’t support that, wish there was max runtime setting or CPH. Worth switching?

  • Long Beach Ed
    Long Beach Ed Member Posts: 1,328
    edited December 23

    There are compromises to be made. It sounds like the boiler is sized to fill the existing radiators. As they fill, steam condenses in them and draws in more steam. But one isn't heating. That radiator gets no steam.

    With an oversized boiler, pressure would build as vents closed, and the last, unheating radiator would see steam directed to it. With a modestly sized boiler, this cold radiator may never heat. Is the boiler too small? Is the venting to fast? Here's where you make your adjustment. Here's where the "over venting" Jake refers to comes to play. Jake knows.

    You would close down some venting to assure sufficient flow gets to the cold radiator to begin condensing in that radiator. Is this slowing down others' heating? Yes it is. Sometimes that is the cost of proper, equal distribution.

    delcrossv
  • ChrisJ
    ChrisJ Member Posts: 16,319

    I completely missed the comment about 1 cold radiator…….. I'm sorry.


    What vents are on all of your radiators currently?

    Single pipe 392sqft system with an EG-40 rated for 325sqft and it's silent and balanced at all times.

  • Jamie Hall
    Jamie Hall Member Posts: 24,984

    I think we need to be a little clearer on one point, and it's a general point. It is NOT really possible to over vent a main. It is possible to waste money on excess venting…

    However, it is very possible to get badly unbalanced venting on radiators on a single pipe system. This is why when one is trying to balance a single pipe system one should always work on reducing the venting on radiators which are heating too fast before one tries increasing venting on ones which are too slow.

    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
    Waher
  • Kjmass1
    Kjmass1 Member Posts: 266

    Bit of a frustrating day, been slowly closing down venting (rads and main) on the short branch, steam really wants to go that way. It really starts to compound once a radiator or branch gets warm, it’s almost impossible to send it to the other longer branch. I do have master shut off valves for each branch, so I’m going to close it off to at least do a cycle or two to force it to the other side and gets those warmed up.

    Is there any math to this? I’ve got main pipe lengths, take offs, EDRs etc, along with 4 air eliminator vents at my disposal. Even with the short main vents flipped over, it still dominates that direction. Thermostat is located in literally the first radiator off that branch too so that is hot and toasty before it even gets to the end of the long branch.

    Again, everything has been balanced for years, so the new boiler and dry steam/drop header is messing with it a bit. Is there a balancing 101 to follow or just try and get the end of mains to close at the same time? When I originally balanced the system I followed the vent mains fast, radiators slow.

  • Kjmass1
    Kjmass1 Member Posts: 266

    Mostly Gorton 4s and 5s, with 2 Hoffman 40s, a 6 and a C mixed in there.

    bburd
  • delcrossv
    delcrossv Member Posts: 1,437

    Had a similar problem. Sometimes extreme measures need to be taken.

    Trying to squeeze the best out of a Weil-McLain JB-5 running a 1912 1 pipe system.
  • Kjmass1
    Kjmass1 Member Posts: 266

    Not too far behind you, I flipped over both Gorton main vents on the short branch and it still went that way lol.

    Installer added inline shutoff valves to the mains off the drop header, for now I’ve just closed down one branch a couple turns and that did the trick pushing stream to the other branch. Hopefully can just dial that in.

  • delcrossv
    delcrossv Member Posts: 1,437

    King valves aren't throttles, but if it's working....

    You may want to put much smaller rad vents on the rads on the "fast" main. The air is still getting out quicker than you'd like.

    Trying to squeeze the best out of a Weil-McLain JB-5 running a 1912 1 pipe system.
  • Steamhead
    Steamhead Member Posts: 17,406

    How's your water cleanliness? Dirty or contaminated water can do this too…………………….

    All Steamed Up, Inc.
    Towson, MD, USA
    Steam, Vapor & Hot-Water Heating Specialists
    Oil & Gas Burner Service
    Consulting
  • dopey27177
    dopey27177 Member Posts: 908

    I sent you how to layout vent valves from Gorton company.

    Go back to my post and open the attachments.

    Jaje

    Kjmass1
  • ethicalpaul
    ethicalpaul Member Posts: 6,812

    it is possible to overvent a main. Lets say you need a single #1 but you have four #2

    Those are vents with a lot of mass that use a lot of steam to heat up and close. Now your main takes longer to close and each of those vents is also a radiator

    NJ Steam Homeowner.
    Free NJ and remote steam advice: https://heatinghelp.com/find-a-contractor/detail/new-jersey-steam-help/
    See my sight glass boiler videos: https://bit.ly/3sZW1el

  • Kjmass1
    Kjmass1 Member Posts: 266

    we did an initial skim last week after install, I just did a quick skim as well as you could seem some oils in the sight glass.

  • Kjmass1
    Kjmass1 Member Posts: 266

    it’s going to have to work for now…Christmas Eve with family coming over. Radiators settled in over night so happy with that, but yeah agree probably shouldn’t have to use those king valves like that.

    I think I need a lot more venting on the long branch now…a project for the new year.