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Number of main vents

Neild5
Neild5 Member Posts: 163
I live in a 20 unit condo building built in 1927. Single pipe steam, original unit was coal, updated at least 3-4 times, last one was 5 years ago with a 1.5 million BTU boiler. Three years ago right after I bought my unit the controller was replaced with a Trs wireless control with 4 sensors. The unit furthest from the boiler is always 8-10 degrees colder than the rest until outside temps drop under 20 degrees then it is 1-2 degrees less. Luckily the contractor the management co uses is not a knucklehead, he admits his limit is cleaning the burners and replacing the igniters. The long main is 85 feet of 6 inch pipe then an additional 35 feet of 4 inch. Where it steps down from the 6 to 4 inch there was 1 Dole #1C vent and a Maid o Mist #1 at the end of the 4 inch. From all the reading I have done I know it is not enough but how much should there be? The short main is 25 feet of 2 inch pipe with a small vent, I can not see the size but the 3 units it feeds are all toasty.
Thanks in advance.
Neil

Comments

  • BobC
    BobC Member Posts: 5,473
    edited January 2016
    For optimal results use 1 Gorton #2 for each 20 ft of 2 " main.
    A ft of 6" main contains 9X the air a ft of 2" main
    A ft of 4" main contains 4X the air a ft of 2" main

    The venting has to be balanced between mains, by their volume, for good steam distribution.

    For optimal venting 20 ft of 2" main needs 1 Gorton #2
    For optimal venting 5 ft of 4" main needs 1 Gorton #2
    For optimal venting 2.2 ft of 6" main needs 1 Gorton #2

    You can get by with less venting but fuel usage can be higher because the builer has to fire longer for steam to get down the mains. Note a 3/4" outlet can only handle the venting needs of 4 (corrected thanks to @EzzyT ) Gorton #2's. Multiple outlets will be required on some mains to handle the number of vents

    Your mains are massively undervented as they are now.

    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
  • EzzyT
    EzzyT Member Posts: 1,290
    @BobC Its 4-Gorton #2's on a 3/4" outlet.
  • nicholas bonham-carter
    nicholas bonham-carter Member Posts: 8,576
    Maybe this is a situation for the use of steam traps as vents.
    The opening and closing temperatures would be better suited to complete venting.
    Someone here is making some tests using traps as vents, but I have not heard the outcome.--NBC
  • BobC
    BobC Member Posts: 5,473
    Asco makes a line of steam rated solenoid valves.

    http://www.ascovalve.com/Applications/News/News8220Steam_HotWaterValve.aspx

    Seems like a good candidate for an option (with a good control scheme) vs a large number of air vents.

    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
  • Neild5
    Neild5 Member Posts: 163
    Wow 45 #2 vents! I doubt the board will approve that expense.
    Thanks for the info. The Asco valve sounds interesting.
  • BobC
    BobC Member Posts: 5,473
    45 #2's would be optimum but you could start with 1/3 that number and see how it does. They don't exactly give the asco steam rated valves away either.

    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
  • KC_Jones
    KC_Jones Member Posts: 5,698
    Neild5 said:

    Wow 45 #2 vents! I doubt the board will approve that expense.

    Thanks for the info. The Asco valve sounds interesting.

    They are spending that money now in wasted fuel. They have already approved it and don't realize it. Personally I would rather spend it once than every year for the rest of my life.
    2014 Weil Mclain EG-40
    EcoSteam ES-20 Advanced Boiler Control
    Boiler pictures updated 2/21/15
    RomanGK_26986764589
  • SWEI
    SWEI Member Posts: 7,356
    Given the size, some alternative options might be worth exploring. Big traps (we've seen Nicholson and Monash models applied here) would be the simplest option. I'd really be tempted to try the solenoid valves along with a small DDC controller. This will produce some interesting data that can be used to optimize the system.
    KC_Jones
  • BobC
    BobC Member Posts: 5,473
    @SWEI i found the price of those steam rated ASCO 8200 series solenoids very high, other manufacturers may be more reasonable. I do agree the possibilities are interesting.

    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