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Question about where to set Pressurtrol cut out

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n1976jmk
n1976jmk Member Posts: 22
edited January 2 in Strictly Steam

Good morning, happy new year! I have a residential Weil-McLain natural gas single pipe steam boiler. I very much enjoy understanding how everything works and want to make everything work as efficiently as possible. I’m about half way though Dan’s book, We Got Steam heat, A Homeowners guide’.

A previous owner’s contractor has our gas boiler set at a 2.0 differential. .5 on cut in, 1.5 on cutout.

Small, history had some issues with the heat this winter but they all are resolved now, needed gas company to replace the meter and some other part which increased the gas pressure, before it was only 3.8, now it’s 6.5. Also, had to replace the control module on the boiler earlier this season too. Fyi, there’s a new last winter Gorton #2 main pipe vent as well. I have a mix of Gorton and Hoffman 1a adjustable vents throughout the house. The house is 3 floors but cast iron radiators just on 2 of the floors. 3rd floor has a mini split with a heat pump, it’s a finished 3rd floor but no one rarely goes up there so I keep the mini split set at 60 F.

With all that said, the boiler is running good and consistent and even heat throughout the house.

There’s no banging or hissing from the pipes or radiators but everything I’ve read so far in the ‘We got steam heat’ book, I should have my cutout set at 1.0 instead of 1.5. 1.0 will use less fuel and be gentler on the heating system.

What real world differences is there? So if I decrease it to 1.0, what changes should I expect? Longer heat cycles (probably only a few minutes longer)? And maybe even more even heat throughout the house? (I just want to understand more).

here’s a screenshot form beestat, most of my heat cycles are around 28 minutes or so.


thanks in advance!
Jonathan

IMG_1287.png IMG_0519.jpeg IMG_0525.jpeg IMG_0526.jpeg IMG_0517.jpeg IMG_0309.jpeg

Comments

  • 109A_5
    109A_5 Member Posts: 3,538
    edited January 2

    " gas boiler set at a 2.0 differential. .5 on cut in, 1.5 on cutout. "

    Looks to me like it is set at 1 for the differential, 0.5 on cut in for a cutout of 1.5 (additive), which is about the minimum and where you want it set at. The setting is the number straight out towards the front of the pressuretrol. If you look behind the black wires the ' Diff ' (Differential) index mark may be printed on the switch body.

    If the Boiler's (Sq. Ft.) is well matched to the radiation EDR (Equivalent Direct Radiation) the system pressure may never come close to tripping the Pressuretrol.

    National - U.S. Gas Boiler 45+ Years Old
    Steam 300 SQ. FT. - EDR 347
    One Pipe System
  • n1976jmk
    n1976jmk Member Posts: 22

    thanks 109_A, let me take another picture this afternoon when I’m home from the office with a better angle.

  • 109A_5
    109A_5 Member Posts: 3,538

    Yellow arrow is the typical label on the switch. The number at the Orange arrow is the actual setting. See the printed vertical line below the screw head.

    image.png
    National - U.S. Gas Boiler 45+ Years Old
    Steam 300 SQ. FT. - EDR 347
    One Pipe System
  • n1976jmk
    n1976jmk Member Posts: 22

    hi 109A_5, here’s pictures of my Pressurtrol I just took. Does it look to be at 1.5 or 1? Thank you!!!

    IMG_1304.jpeg IMG_1305.jpeg IMG_1306.jpeg IMG_1307.jpeg
  • Jamie Hall
    Jamie Hall Member Posts: 26,884

    it's set a bit above 1.5 for the differential — which is more than it should be. Set it to 1

    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
    n1976jmk
  • n1976jmk
    n1976jmk Member Posts: 22

    ok, thank you Jamie hall, I just changed it. Does this look good? Thank you!!!!

    IMG_1310.jpeg IMG_1311.jpeg IMG_1312.jpeg IMG_1313.jpeg
  • 109A_5
    109A_5 Member Posts: 3,538

    That setting looks better.

    The wires still block the view of the labeling on the switch which may have made the setting position index more confusing.

    image.png
    National - U.S. Gas Boiler 45+ Years Old
    Steam 300 SQ. FT. - EDR 347
    One Pipe System
    n1976jmk
  • n1976jmk
    n1976jmk Member Posts: 22

    thanks 109A-5, let me take another look this evening and I’ll snap a pic too. Appreciate everyone’s time a lot!

  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 19,721

    @n1976jmk

    You answered your own question. Its working good I wouldn't fiddle with it. 1/4 Psi or 1/2psi one way or the other won't change much.

    n1976jmk
  • n1976jmk
    n1976jmk Member Posts: 22

    thanks, but let me ask you a question, when I turned it down from 1.5 to 1.0, does it matter at all if the boiler is not even hitting that high to begin with? Sorry about these questions, just want to understand the reasons I’m doing everything and like to know intimately how and why everything works. Thanks!!!

  • 109A_5
    109A_5 Member Posts: 3,538

    Lower pressure is better, if the pressuretrol NEVER trips that is best.

    As an example my boiler runs at never more than 2 inches of Water Column which is about 0.07 PSIG no where near 1.5 PSIG.

    In an oversized boiler situation the pressuretroll limits the pressure by shutting off the burner. Also there really is no point to running the burner just to build pressure. And excessive pressure can damage things.

    Also if the boiler happens to get way over filled with water (like up into the pipes) the pressuretrol will trip disabling the burner.

    National - U.S. Gas Boiler 45+ Years Old
    Steam 300 SQ. FT. - EDR 347
    One Pipe System