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Main vents and Pressuretrol settings

I just joined "the wall," and have a question. Last fall, we had a new oil-fired steam boiler installed in our Victorian era home. The house originally had a coal boiler: the single steam piping has not been altered from the original, although we know that there were at least two other oil burners in the house following the original coal boiler. Having done this, I was determined to learn as much as I could about the system, and got Dan's books, The Lost Art of Steam Heating and Greening Steam. I'm finding them immensely helpful as well as being great fun to read...and it didn't take me long to find some things in my system that need to be addressed.
First, there are no vents on the mains. Last week I talked to the extremely knowledgeable and helpful folks at Gorton about this, and we have a game plan. I've already replaced all the individual radiator vents, some of which were decades old. Also, the Honeywell Pressuretrol (PA404A1009) is set way higher than Dan's recommendations. It's at 4psi on the little slider outside the cover; I have not yet checked the inside setting.
Here is my question: The system is functioning well, with no water hammer and no spitting vents. The boiler does not short-cycle, and we are warm. That being the case, my current plan is to wait until the weather breaks to install the main vents to avoid having to shut down the boiler in February. So should I adjust the Pressuretrol now, or wait until the main vents are in place? I do not know how one factor might affect the other.
By the way, the guys who installed the boiler have done a lot of work for me over the years. They have always been very competent and very reliable, but now it becomes obvious to me that they're not familiar with the finer points of steam system "tuning." They need to become acquainted with the "Dead Men!"


  • Have your boilermen take a look at the venting locations, and determine how easy it may be to put those vents (and plenty of them) in right now.
    Leave your present radiator vents in place until you have the main vents in place. I have some decades old radiator vents in place, and they work just fine. Gorton make good vents, but may not always give the right advice about how to use them.
    When the main vents are in, and the pressure turned down, as low as you can get it, verified by a good low pressure gauge (0-3 psi), then examine the performance of the radiators as regards the speed of steam arrival. Identical pats of butter, on plates should all melt at the same time, from a cold start. If some radiators are lagging behind, then a larger vent may be needed. I would use Hoffman 1A's which are adjustable.
    When this is done, sit down next to one of the rads, and enjoy some toasted sourdough rye bread with all the butter!--NBC
  • Lance
    Lance Member Posts: 258
    the 404 is fine if it functions as set, just keep it at 1psi give or take 0-1psi differential wheel setting. these pressures are average and can vary by your systems design. Instead of main air vents the last radiator at the end of main can have the largest air vent opening. A poor mans solution to no end of main air vents.
  • Fred
    Fred Member Posts: 8,542
    The largest radiator vent, placed at the last radiator or anywhere else on the system is not going to replace good Main venting. Do put the main vents on and enough to get the mains filled with steam as quickly as possible. The rule of thumb is the equalivent of 1 Gorton #2 for every 20 feet of 2" main.
    As far as the pressuretrol is concerned, set the scale on the front down to .5PSI and the white wheel inside to "1". You can do that now. The lower you keep the pressure, the better the steam will move through the system.
  • vaporvac
    vaporvac Member Posts: 1,520
    At what pressure is your system currently running? I'd deal with the main venting before replacing the rad vents; they may just need cleaning with some vinegar as NBC stated above. Maybe it's better to invest in a low-pressure gauge to start. The pstat is just a limiting device; it doesn't "make" your pressure run at that setting. That's determined primarily by your main venting and how well your rads edr is matched to the edr of the boiler.
    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