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Help! I have no main vents! + problem radiator

JimmyNJ Member Posts: 107
Hello everyone,

Great site!!  I've learned a lot about my steam system from reading on this site, so much that I've discovered some issues that I would like some help addressing from all the kind folks here on the Wall that have much more experience than I do.

Question/problem #1:  My steam system is single pipe, and I just realized that I have no Main  Vents on it!!!  So the rads in the house are effectively venting not just the air in them but the air in the Mains as well (which I know from this site is not very good).  I've attached a diagram of the Main Vents + pictures of the end of each Main ("left & "right") with proposed Main Vent install placements.  Since the left main is a fairly short one - would I be okay with just a Gordon #1 there and then a Gordon #2 on the "right" main since that pipe is about 32 feet in total?  Main Steam line piping is 2" I think if that helps.

Question/problem #2:  I have a fairly big radiator placed pretty far from the boiler that doesn't get "hot" unless I bring up the house temp about 10 degrees (so working the boiler for more than a few minutes).  I usually have the thermostat set at 67 - and when it gets to 66 and the boiler starts firing the radiator in the family room doesn't even get warm (the supply line to it is only hot for about 1-2 feet).  The family room radiator has a vari-valve (heat timer) on it in the full open position so i know venting capacity is not an issue - but I am suspecting that since the other radiators on the first floor also have vari-valve vents (in various "mid" to "closed") positions that they may be part of the problem as they hog all the steam and the thermostat reaches the shut-off point before the boiler has been on long enough to create enough steam that can get to the family room radiator.  I was thinking about getting some Gordon #4 and #5's on the radiators on the same floor as the family room radiator....but should I DO ANYTHING before I install Main Vents?  Any suggestions here would be appreciated.

Question #3:  The boiler is currently connected to a White Rogers 1F80-361 in our eat in kitchen - We would actually like to use that wall space and since we got a Honeywell PRO 4000 thermostat in the hallway between our "old" part of the house and the new family room which has that troublesome radiator in the back (we expanded our house last year and now have zoned AC - so the PRO 4000 is only used for cooling the first floor today).   Would there be any issue to connect the boiler to the PRO 4000 thermostat (as it is actually much better placed with no radiators right by it)?

Thanks for any insight/help!



  • Jamie Hall
    Jamie Hall Member Posts: 22,928
    Well, let's see here...

    First things first -- that insulation is better than nothing, but more -- 1" fibreglass -- would be much better.

    Those main vent locations look OK.  I would definitely put a #2 on the longer main.  A #1 on the short main would probably be OK, but a #2 there wouldn't hurt anything.

    On that big radiator -- it probably is a situation of the radiators before it on the line hogging the steam, but until you put main vents on there isn't much point in playing with the radiator vents, as you have already figured out.  Once the main vents are on, then you can start fiddling with the radiator vents.  What you are looking for at that point is the various radiators heating their respective spaces the way you want them, not necessarily that they get hot all the way across (unless you are coming up from a setback; that's another story).

    I don't see any reason not to use that Honeywell thermostat, particularly if it is in a better location.  I'm not completely up on the wiring which would be involved, but it shouldn't be that much hassle.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • JimmyNJ
    JimmyNJ Member Posts: 107
    Thanks Jamie!

    Really appreciate your feedback!   Yes I know that the old tape insulation is pretty inadequate, I will take the time this summer to scrape it off and put the fiberglass insulation on it.

    I just can't believe that no main vents existed - from reading other posts here it looks like standard procedure to have Main Vents on a single pipe system.  Looks like my plumber will get another job from me :) 

    Thanks again for taking the time to read my questions and providing feedback.

  • JStar
    JStar Member Posts: 2,752

    Thanks for participating on The Wall!

    Agreed that those vent locations look good. I would use a Gorton 2 for every 20 feet of 2" main. Try to get the steam main full in about 5 minutes. You could also add on a Vaporstat in conjuction with the new venting to run at super low pressures. Low pressure = low fuel usage.
  • Steamhead
    Steamhead Member Posts: 16,728
    In the third pic

    the first elbow is installed wrong. It's a reducing elbow turned on its side, creating a water pocket. A main vent installed there will be hammered to death.

    Have it repiped, either with an eccentric reducer or by running the pipe full size to the wall and making the reduction where the pipe turns down toward the floor. While doing this you can add a tee for the main vent.

    How long are those steam mains, and what pipe size?
    All Steamed Up, Inc.
    Towson, MD, USA
    Steam, Vapor & Hot-Water Heating Specialists
    Oil & Gas Burner Service
  • JimmyNJ
    JimmyNJ Member Posts: 107
    In the third pick

    Thanks for noticing that!   I will take your advice and have the plumber just re-pipe from the main to the wall.  So you don't think that would be a problem having the Main vent on a Tee where the Main ends/the return starts?  I've been reading on this site that having the Main Vent about 15" away from where the pipe turns into the return is best practice...but maybe it doesn't really make a big difference?

    Main Steam pipe is 2" and the total length of piping of the "right main" (which ends in that third picture) is about 32 feet (you can see my crude drawing in the PDF right below the pictures in my original post if you want to take a look).  The length of piping on my "left main" is about 11 feet in total.

    Thanks for all the insight & tips!  Really appreciate it.

  • VA_Bear
    VA_Bear Member Posts: 50
    Sounds like you have your piping and vent questions covered...

    I'll touch on your thermostat question; the wiring of a thermostat to control two systems with different power supplies can be done, but can also get a little tricky. Your HW 4000 series will usually have the capability to run split power supplies, but unless you are REALLY familiar with the controls on both systems and your thermostat, spend the money to have a contractor do the changeover for you. I have done many followups for customers who have destroyed two power supplies and a thermostat in a split second by a minor mistake and the repairs were often at least twice what my doing the rewire would have been. Just remember, the manufacturers have a special machine that puts a blue smoke in their parts and electric controls don't work when you let the blue smoke out!
  • JimmyNJ
    JimmyNJ Member Posts: 107

    Appreciate the input - I did for a brief moment think about trying to do the hookup by myself, but decided that I didn't want to be responsible for figuring out where to drill in the basement and fishing the new thermostat wire and doing the hookup so I plan on having the HVAC company that installed the thermostat and hooked it up to our 1st floor AC do it.

    I just ordered the Gorton vents (plus a 0-5 PSI gauge so I can see what's going on with the system).  Will update this thread after I recieve the parts and the plumber installs the Main Vents.   Thanks for eveyone's help!

  • JimmyNJ
    JimmyNJ Member Posts: 107
    Another Question on Installation of the Main Vents...

    I had another thought on the issue of installing main vents on my 1 pipe system.  I had assumed that I would need my plumber to take apart the sections where I wanted to install the Main Vents in order to install T's (So the Main Vents have somewhere to screw in), but I was wondering if it would be advisable to instead drill & tap the holes for the Main Vents on the existing cast iron mains(which are 2" I believe).  I got the Gorton #1 and #2 which I believe have 1/2" thread size.

    Any thoughts on this approach vs. trying to take the existing piping apart? (which I am sure could be a non-trivial job as the pipes are probably pretty fused together at this point).  

  • JeffM
    JeffM Member Posts: 182

    I wouldn't advise drilling and tapping a pipe to install a vent, as the pipe wall isn't really thick enough to give you enough good threads. It might work in a pinch, but isn't ideal. I had a similar situation when I bought my house and had my heating contractor drill holes in the mains and weld Thread-o-let fittings over them, which gives a much better threaded connection. I chose this over trying to take apart my piping, and would bet that it's faster too. Just make sure the welder takes precautions against flying sparks which can be dangerous in an old house.
  • JimmyNJ
    JimmyNJ Member Posts: 107

    Thanks for the tip!  Will ask my plumber about that option as well.