Welcome! Here are the website rules, as well as some tips for using this forum.
Need to contact us? Visit https://heatinghelp.com/contact-us/.
Click here to Find a Contractor in your area.

Two-pipe steam system - need venting (and other) advice

I'm a homeowner (and not especially good with plumbing style work, but should be able to handle some basics) with
a 3-story home built in the 1920s that has a 2-pipe steam system. We've been here 10 years and the system works OK
overall (maybe give it a B grade). No horrible banging noises - but some "ticking" and gurgling sounds and some vents that hiss quite a bit (more on that below).

Having just picked up and read the "We Got Steam Heat!" book, I'm hoping
we can maybe make the system work more efficiently to save money and maybe be a bit quieter. We also have some
radiators that don't heat up as quickly as the others (or maybe not at all if the boiler turns off before they get
around to it).

Some details abut the system we have (and some pictures also included):

- Boiler Model GSB-262E1D by Vaillant Corporation

- pressure seems to be set at .5 as seems ot be recommended

- most of the main piping in the basement is pretty well insulated - but this does not seem to be true for that closest to the boiler

- 3 original style radiators on 1st floor - no vents - all seem to work well

- 3 baseboard radiators on 1st floor - added by previous owner as part of renovations - each with a vent - also seem to work OK

- four radiators on 2nd floor - two of which don't heat up very well - no vents

- 3 radiators on 3rd floor - one with a vent which hisses quite a bit - but all work pretty well

- would assume that the thermostatic radiator traps are very old and may not be working well - but I don't know

- Hoffman Differential Loop No 1 with No 76 Main Vent Vaccuum Valve attached - seems to be only main vent (and seems not to work)

We've never had any real problems with the overall system - other than a leaky vent here or there and have had very little service
done to it over the last 10 years - mostly just annual checks of the boiler itself

I'm looking into whether we can make it work even better and just bought and read Dan's "We Got Steam Heat!" book - only to learn (I think) that with a two-pipe system the radiators should not have any vents.

As I understand it, the vents should only be on the main return lines. I've looked around as best I can with the drop ceiling and walls
in the basement so far and the only vents I have found is the one attached to the Hoffman Differential Loop (can't say I know what that even
is - will have to move on the "Lost Art" book by Dan) - which seems to be a very old Hoffman No 76. This does not seem to be working at all,
but maybe partly due to the other vents releasing the pressure instead?

So - while I assume our system have various problems that may require attention should I start by getting a replacement for the Hoffman 76
vent? Should I have the vents from other radiators removed? Should I have the piping closest to the boiler better insulated? image


  • Jamie Hall
    Jamie Hall Member Posts: 21,094
    Love those differential loops. What makes you think the 76 isn't working? They are pretty sturdy. They also don't make any fuss and bother when they are venting; it can be remarkably difficult to tell is they are open! If you do want to replace it, go ahead; a nice Gorton #2 would fit or, if you have more pipe to vent, two or three of them on an antler.

    Also get your pressure down. Way down. Hoffman equipped systems need to run at less than 10 ounces, and you can't do that with a pressuretrol; you will need a vapourstat.

    However, as I said recently in another thread, if you want the system to really work properly, do NOT install vents anywhere else in the system.

    Including the radiators. The fact that they have vents on them indicates either that the traps are failed closed, and they are behaving as one pipe radiators (quite possible) or that they really aren't doing anything at all, also quite possible, or that someone sometime had heard that steam systems need radiator vents, and didn't think.

    The next thing to do is to attack the traps and make sure that all of them are working properly. That includes -- perhaps especially -- the traps which should be there connecting the ends of the steam mains to the ends of the dry returns. These are called crossover traps (they are usually the same as radiator traps) and are critical to the proper functioning of the system.

    Do that right along with getting the near boiler piping insulated.

    Once you get all the traps working properly, and your pressure down to where it should be, you will find that you can balance the system beautifully with the radiator valves (although that will take some fiddling -- always does).
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • Steamhead
    Steamhead Member Posts: 15,986
    And it looks like that boiler is not piped correctly. It's (here we go again) a re-branded Dunkirk, which is very sensitive to improper piping.

    Regarding the vent- originally these systems with this type of Differential Loop had Hoffman #11 vents, which were HUGE. That #76 is a toy by comparison. Go with a Gorton #2 on the Loop, since it's the biggest vent you can get. Then remove all the radiator vents and plug the openings. If any radiators don't heat after doing this, fix the traps. Replacement trap parts are available, so you don't need all new traps.
    All Steamed Up, Inc.
    Towson, MD, USA
    Steam, Vapor & Hot-Water Heating Specialists
    Oil & Gas Burner Service
  • bjdoherty
    bjdoherty Member Posts: 4
    Thanks for feedback so far. It seems that replacing the Hoffman 76 and removing the vents at the radiators, as well as getting more insulation in place closer to the boiler, are things I can handle without professional help. Same is probably not true for the traps (but I'll look into that) or the change to a vapourstat to get lower pressure, much less the fixes for any improper near boiler piping. I'll plan to start with what it seems I can handle myself, and then look into a professional consultation re: the other issues. I'm near Philadelphia, PA, so and referrals to local steam pros would be welcome.

    It seems my pictures loaded in upside down so I'll provide better pictures of the near boiler piping later.

    As for the current state of the Hoffman 76, I was basically assuming it may not be working as 1) it looks very, very old and 2) I don't hear it venting in any way. However, maybe that is normal and/or taking place due to the other vents that shouldn't be in place releasing the air that the Hoffman usually would.

    Assuming I can get it in place easily enough, the investment in a new Gorton #2 seems reasonable enough that I'll plan to start there, then remove the radiator vents and see how the system works then.

    I hadn't mentioned it before, but some of the radiator valves don't seem to work particularly well either, so they may have to be repaired along with the traps if they are to be used to balance the system (when it is working better).

  • bjdoherty
    bjdoherty Member Posts: 4
    I got a Gorton #2 and installed it where the apparently non-working Hoffman #76 had been on the Differential Loop. I also removed the vents on the radiators that had them and plugged those. All seemed to go well during testing. I could hear the Gorton really venting some air when cycle stated.

    However, when the system really fired up this morning (and it had gotten cold overnight) I ended up with water leaking out of the Gorton #2. At first I thought my connections could have too been loose - but it was actually coming out of the body of Gorton.

    So- two questions to get started:

    1) Does this mean I have to get the Gorton connected with
    more separation from (i.e. more piping above) the Differential Loop?

    2) Would the Gorton now be damaged? Still seems to vent OK - but not sure how well it will close now.

  • KC_Jones
    KC_Jones Member Posts: 5,409
    In all likelihood it is still a pressure issue and possibly being compounded by bad near boiler piping. I am not an expert on these systems, but it has been mentioned many times they do not like excess pressure. Think ounces not pounds. If you are running a pressuretrol you will want to switch to a vaporstat and add a good low pressure gauge. I am sure the more knowledgeable will comment as well.
    2014 Weil Mclain EG-40
    EcoSteam ES-20 Advanced Boiler Control
    Boiler pictures updated 2/21/15
  • Jamie Hall
    Jamie Hall Member Posts: 21,094
    The Gorton might well benefit from a taller nipple or, better, being offset several inches (go up from the differential loop, the over 6 inches or so (make sure that line can drain back to the loop!) then up again.

    And check pressure. Cutout not over 10 ounces absolute maximum!
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • I would say over-pressure too. Probably will still need more Gorton 2's, once the pressure is under control.--NBC
  • vaporvac
    vaporvac Member Posts: 1,520
    I believe @jstar services your area. Try and keep the vacuum if you can. Once you get the other stuff working you'll be amazed at the improvement.
    Two-pipe Trane vaporvacuum system; 1466 edr
    Twinned, staged Slantfin TR50s piped into 4" header with Riello G400 burners; 240K lead, 200K lag Btus. Controlled by Taco Relay and Honeywell RTH6580WF
  • bjdoherty
    bjdoherty Member Posts: 4
    OK - thanks for the suggestions. I tried adding some vertical and horizontal distance between the Gorton and the differential loop piping but it didn't help. Still ended up with water coming out of the top of the Gorton.

    Since it seems I can't make the change to the Gorton for better venting w/o first addressing the pressure issues, and doing that is beyond my DIY level of ability, I will need to look for some professional assistance.

    Any references for Philadelphia PA area steam pros are more than welcome.

    Vaporvac - not clear what you mean by "try and keep the vacuum if you can". The Hoffman #76 vent?
  • Jamie Hall
    Jamie Hall Member Posts: 21,094
    You will certainly need a vapourstat to control your pressure. The only way water can get to that vent is if the differential loop trips -- which it shouldn't if the pressure is right.

    Steamhead is, I think, in Baltimore He's one of the very best, and might come up or know someone.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • vaporvac
    vaporvac Member Posts: 1,520
    edited December 2014
    @jstar is about an hour away and may make the trip. I'm pretty sure he's travelled further than that for steam. :) He's under "Find a Contracter". His company is Thatcher Heating & Cooling.

    Obviously @steamhead would also be an equally great choice, just a little further out.

    I think there may be other vacuum vents available, but others are better versed on that. I have my original vacuum vent and it seems to work well enough. I have some work to do on my system first and then I'll judge. With vacuum, one only needs to expel the air on the first cycle, (unless it's super cold) . After that it continues heating without gas until the Tstat drops and then it fires in a vacuum . That's what my system does anyway. It delivers heat to the rads quickly, they stay hot longer and it's very economical.
    Two-pipe Trane vaporvacuum system; 1466 edr
    Twinned, staged Slantfin TR50s piped into 4" header with Riello G400 burners; 240K lead, 200K lag Btus. Controlled by Taco Relay and Honeywell RTH6580WF
  • Fizz
    Fizz Member Posts: 547
    Jstar lives by "have steam will travel"! We live in northeast Pa, between Scranton/Wilkes-Barre, and he made trip 2x, once to assess problem, and 2nd time to correct it! He loves steam and will travel within reason, and sometimes beyond. Go for it!
  • gcp13
    gcp13 Member Posts: 122
    edited December 2014
    If you hear the Gorton venting loud you need more vents
    The Hoffman loop is 3/4 off the top you need to come off and 90 over to a 3/4 x 1/2 tees. You can add up to 4 Gorton # 2's for a 3/4 line.
    I just worked on one and got lots of info here.
    if you add a low pressure gauge you can see how the boiler reacts as the pressure goes up,if the vent starts to spit water you can see at what pressure.
    with that gauge you can mimic a vaporstat by watching the pressure climb and shut down the boiler at 6-8 oz. and see how she runs
    that should convince you into replacing the pressuretrol with a vaporstat as well as a savings in gas