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Weil-MClain EG-55 - unknown device - hissing sound

EdwinDEdwinD Posts: 89Member
edited October 5 in Strictly Steam
After running my EG-55 for about an hour, I start to get a hissing sound from the device attached below. Should it behave this way. It's appears to be
a vintage piece, should it be replaced? There is only one of them and its connected to a pipe running to the boiler and the steam pipes leading to the raidators. It looks like some sort of relief device. Advice please. Thanks.

Comments

  • Jamie HallJamie Hall Posts: 8,534Member
    That's a vent. An elderly vent. I presume it's piped to the vertical pipe a little way down, out of the picture? It's hissing because the system finally built up some pressure (this is good. by the way -- it should take time to build pressure).

    Is this one pipe steam? Only one pipe going to each radiator, and small vent on the other end of the radiator? Or two pipe -- one pipe going in (often with a valve on it) and one pipe out (often with a rather odd looking elbow fitting - a trap)?

    Are there any other such devices on the system?
    Jamie



    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England.



    Hoffman Equipped System (all original except boiler), Weil-Mclain 580, 2.75 gph Carlin, Vapourstat 0.5 -- 6.0 ounces per square inch
  • EdwinDEdwinD Posts: 89Member
    edited October 5
    @Jamie Hall Yes, its piped to a vertical pipe that then runs horizontal to the boiler and goes vertical to horizontal ceiling mounted boiler pipe. There are no other devices of this type.

    The sytem is a 2 pipe system as shown below. Thanks!

  • FredFred Posts: 6,583Member
    What pressure is your boiler running at? That Hoffman #75 vent should stay closed and not hiss after steam hits it, unless the pressure is too high and causing the vent to open or the Vent is defective and not fully closing. Additionally and In all probability, that vent is too small for your system anyway and probably needs a larger capacity vent. How long is that main? Do you only have one main? If there is another Main, it should be vented also. Why is the boiler running for a full hour? How long does it take to steam to get to that vent? That too is a good indicator of a vent being inadequate to vent the main quickly.
  • SteamheadSteamhead Posts: 12,293Member
    Is it on the steam pipe or return pipe?

    If the former, there needs to be one on the return pipe as well.
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  • BobCBobC Posts: 4,808Member
    I had two of those Hoffman 75 vents fain in just over two years so I would not replace it with the same vent. If that is the only main vent I would replace it with the Barnes and Jones Bigmouth vent. If it is NOT the only main vent you might have to replace all the main vents to keep the system balanced.

    The Bigmouth costs no more than the Hoffman, is much higher capacity, and is much better built - the bigmouth is usually available at Amazon. The other option would be 2ea of Gorton #1 or maid O Mist #1 using an antler, this would probably cost a bit less but be more work.

    Bob
    Smith G8-3 with EZ Gas @ 90,000 BTU, Single pipe steam
    Vaporstat with a 12oz cut-out and 4oz cut-in
    3PSI gauge
  • Jamie HallJamie Hall Posts: 8,534Member
    Just remember if you do decide to go with the BigMouth, that it won't close against water, so if there is that possibility -- don't use it. On the failure rate of the Hoffman 75s -- I have one on one of my systems, which has been working just fine for the last almost 90 years now.
    Jamie



    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England.



    Hoffman Equipped System (all original except boiler), Weil-Mclain 580, 2.75 gph Carlin, Vapourstat 0.5 -- 6.0 ounces per square inch
  • BobCBobC Posts: 4,808Member
    I think they may have changed something in the last 5 or 6 years or so because I've heard of others having problems with recent 75's.

    In any case I don't recommend them any more, better to go with Gorton, MOM, or B&J depending on the application.

    Bob
    Smith G8-3 with EZ Gas @ 90,000 BTU, Single pipe steam
    Vaporstat with a 12oz cut-out and 4oz cut-in
    3PSI gauge
  • Dave0176Dave0176 Posts: 826Member
    I always thought the green Hoffman’s were Hot water vents??
    DL Mechanical LLC Heating & Cooling 732-266-5386
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  • FredFred Posts: 6,583Member
    edited October 7
    Dave0176 said:

    I always thought the green Hoffman’s were Hot water vents??

    The green ones were the older Hoffman 75's (for steam). Hoffman decided a few years ago to save a few pennies by not painting these vents anymore and just leave the raw copper. @BobC , I too think they did something else on the internals to save some money because they just don't seem to have the life/reliability they had 10+ years ago.
  • EdwinDEdwinD Posts: 89Member
    edited October 9
    Fred said:

    What pressure is your boiler running at? That Hoffman #75 vent should stay closed and not hiss after steam hits it, unless the pressure is too high and causing the vent to open or the Vent is defective and not fully closing. Additionally and In all probability, that vent is too small for your system anyway and probably needs a larger capacity vent. How long is that main? Do you only have one main? If there is another Main, it should be vented also. Why is the boiler running for a full hour? How long does it take to steam to get to that vent? That too is a good indicator of a vent being inadequate to vent the main quickly.

    @Fred After running for 1 hour below is the pressure reading -- I was testing a new Vaportstat and Pressuretrol and I just added new fill water along with 1 1/2 Steamaster tablets.



    After about 75 minutes, the pressure started to rise - see below. At about this time the #75 vent began to hiss.- not loudly - but hiss nonetheless.



    I have lmited knowledge about steam boler terms - what is a main?

  • FredFred Posts: 6,583Member
    @EdwinD said: I have limited knowledge about steam boiler terms - what is a main?

    A main is the larger pipe that runs around the perimeter of your basement or runs in one or two directions and from which you radiator run-out pipes branch off heading to your radiators.

    Given the pressures on your gauge, I would say That Hoffman 75 vent should be replaced. It should not open after it closes and while the boiler is producing steam.
  • nicholas bonham-carternicholas bonham-carter Posts: 7,286Member
    edited October 10
    A larger vent such as a Gorton #2, or a Big Mouth will let the air out faster, and reduce your firing time, saving gas. The Big Mouth is a better made vent.
    Order the collection of steam books from the store here, and you will soon know as much as you need about steam systems-sometimes more than many local pros!!—NBC
  • EdwinDEdwinD Posts: 89Member
    Fred said:

    @EdwinD said: I have limited knowledge about steam boiler terms - what is a main?

    A main is the larger pipe that runs around the perimeter of your basement or runs in one or two directions and from which you radiator run-out pipes branch off heading to your radiators.

    Given the pressures on your gauge, I would say That Hoffman 75 vent should be replaced. It should not open after it closes and while the boiler is producing steam.

    @Fred Thanks! Will do a replacement on the Hoffman 75 vent.
  • EdwinDEdwinD Posts: 89Member
    edited October 16
    EdwinD said:

    Fred said:

    @EdwinD said: I have limited knowledge about steam boiler terms - what is a main?

    A main is the larger pipe that runs around the perimeter of your basement or runs in one or two directions and from which you radiator run-out pipes branch off heading to your radiators.

    Given the pressures on your gauge, I would say That Hoffman 75 vent should be replaced. It should not open after it closes and while the boiler is producing steam.

    @Fred Thanks! Will do a replacement on the Hoffman 75 vent.
    @Fred Oh yes, meant to say it's a one main system.
  • EdwinDEdwinD Posts: 89Member
    edited October 16

    A larger vent such as a Gorton #2, or a Big Mouth will let the air out faster, and reduce your firing time, saving gas. The Big Mouth is a better made vent.
    Order the collection of steam books from the store here, and you will soon know as much as you need about steam systems-sometimes more than many local pros!!—NBC

    @nicholas bonham-carter I 've decided to go with the Barnes & Jones Big Mouth Vent from Amazon. I'll let you know how it goes. And I will be ordering the collection of steam books from the store. I have truly enjoyed the experience gained in making my boiler more "cutting edge." I'm excited! Thanks again!

  • EdwinDEdwinD Posts: 89Member
    BobC said:

    I had two of those Hoffman 75 vents fain in just over two years so I would not replace it with the same vent. If that is the only main vent I would replace it with the Barnes and Jones Bigmouth vent. If it is NOT the only main vent you might have to replace all the main vents to keep the system balanced.

    The Bigmouth costs no more than the Hoffman, is much higher capacity, and is much better built - the bigmouth is usually available at Amazon. The other option would be 2ea of Gorton #1 or maid O Mist #1 using an antler, this would probably cost a bit less but be more work.

    Bob

    @Bob. Thanks! Just purchased the Bigmouth at Amazon. Can't wait to install it.
  • nicholas bonham-carternicholas bonham-carter Posts: 7,286Member
    I wonder why it took 75 minutes to start showing signs of pressure. Usually inadequate main vents will show a high reading in a shorter time, as the air is being squeezed out of bad vents.
    Read up on “clocking the gas meter” here and make sure your boiler is getting the required amount of gas.—NBC
  • EdwinDEdwinD Posts: 89Member

    I wonder why it took 75 minutes to start showing signs of pressure. Usually inadequate main vents will show a high reading in a shorter time, as the air is being squeezed out of bad vents.
    Read up on “clocking the gas meter” here and make sure your boiler is getting the required amount of gas.—NBC

    @nicholas bonham-carter Will do. Thanks.
  • EdwinDEdwinD Posts: 89Member
    edited October 16

    I wonder why it took 75 minutes to start showing signs of pressure. Usually inadequate main vents will show a high reading in a shorter time, as the air is being squeezed out of bad vents.
    Read up on “clocking the gas meter” here and make sure your boiler is getting the required amount of gas.—NBC

    @nicholas bonham-carter

    Here's what I got:
    6.5 RPM (1/2 CF dial) x 30 = 195 CF/HR
    (tested twice)
    195 CF/HR x 1000 = 195,000 BTU/HR

    My Weil-MClain EG-55 is rated at 200 AGA Input MBH
    So it appears my boiler needs a lttle more gas - about 5,000 more BTU per hour. Am I reading this correctly? Thanks
  • EdwinDEdwinD Posts: 89Member
  • EdwinDEdwinD Posts: 89Member
  • FredFred Posts: 6,583Member
    @EdwinD , Your boiler/gas supply is fine. It took 75 minutes because your boiler is properly sized to the connected radiation. Even with bad or inadequate vents, some of them are still venting and, as you noted, that Hoffman 75 was opening when steam was being produced so it also prevented any possibility to build pressure. You are good to go! Change out that Hoffman 75 for a BigMouth and enjoy the system.
  • EdwinDEdwinD Posts: 89Member
    edited October 16
    Fred said:

    @EdwinD , Your boiler/gas supply is fine. It took 75 minutes because your boiler is properly sized to the connected radiation. Even with bad or inadequate vents, some of them are still venting and, as you noted, that Hoffman 75 was opening when steam was being produced so it also prevented any possibility to build pressure. You are good to go! Change out that Hoffman 75 for a BigMouth and enjoy the system.

    @Fred. Great. I should have BigMouth tomorrow. Can't wait. Thanks!

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