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Blow-down in vacuum

Fizz
Fizz Member Posts: 547
Has anyone had any issues with blow-down of boiler in vacuum? I've been doing it by returning to pressure. Concern for LWCO during vacuuum b-d with air rushing-in. Legitimate concern or not?

Comments

  • ChrisJ
    ChrisJ Member Posts: 15,592
    I don't see how you could do a blowdown in a vacuum?

    Single pipe quasi-vapor system. Typical operating pressure 0.14 - 0.43 oz. EcoSteam ES-20 Advanced Control for Residential Steam boilers. Rectorseal Steamaster water treatment
  • Fizz
    Fizz Member Posts: 547
    That's what I thought, but waited to hear from guys' in the know.
    Thanks Chris.
  • PMJ
    PMJ Member Posts: 1,265
    You can't do those things in vacuum. I bd the lwco in the brief part of the cycle when there is no vaccum.
    1926 1000EDR Mouat 2 pipe vapor system,1957 Bryant Boiler 463,000 BTU input, Natural vacuum operation with single solenoid vent, Custom PLC control
  • Fizz
    Fizz Member Posts: 547
    Thanks PMJ, will try it. I'm amazed that the boiler hasn't required any extra water this season, and the water has been fairly clear. Added benies for vacuum?
  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 15,455
    If you blow the LWCO down in a vacuum the float will jump up and down risking damage to it. not good
  • PMJ
    PMJ Member Posts: 1,265
    Fizz said:

    Thanks PMJ, will try it. I'm amazed that the boiler hasn't required any extra water this season, and the water has been fairly clear. Added benies for vacuum?

    I think so. Air is the enemy really. It interferes with distribution and it causes corrosion.

    1926 1000EDR Mouat 2 pipe vapor system,1957 Bryant Boiler 463,000 BTU input, Natural vacuum operation with single solenoid vent, Custom PLC control
  • gerry gill
    gerry gill Member Posts: 3,078
    I have a customer who has a Dunham vapor vacuum system. The original Dunham air eliminator still is there, and it has a vacuum check on it. If the boiler has recently ran, (like in the last day) you can open the drain valve and nothing comes out. Take the vaporstat off and woosh, out comes the water, as air rushes in via the pigtail. When we service the boiler, thats the only way we can drain it below the ports we wish to open.

    As a side note, i asked her how her steam distribution is throughout the house, She perked right up and said 'great!'
    gwgillplumbingandheating.com
    Serving Cleveland's eastern suburbs from Cleveland Heights down to Cuyahoga Falls.

  • PMJ
    PMJ Member Posts: 1,265

    I have a customer who has a Dunham vapor vacuum system. The original Dunham air eliminator still is there, and it has a vacuum check on it. If the boiler has recently ran, (like in the last day) you can open the drain valve and nothing comes out. Take the vaporstat off and woosh, out comes the water, as air rushes in via the pigtail. When we service the boiler, thats the only way we can drain it below the ports we wish to open.

    As a side note, i asked her how her steam distribution is throughout the house, She perked right up and said 'great!'

    Great to hear there is some natural vacuum still in operation Gerry.

    Is there a vacuum gauge on that system to see how much vacuum there is?
    1926 1000EDR Mouat 2 pipe vapor system,1957 Bryant Boiler 463,000 BTU input, Natural vacuum operation with single solenoid vent, Custom PLC control
  • gerry gill
    gerry gill Member Posts: 3,078
    You know, i don't think i even looked...but i will next time i go there!
    gwgillplumbingandheating.com
    Serving Cleveland's eastern suburbs from Cleveland Heights down to Cuyahoga Falls.

  • PMJ
    PMJ Member Posts: 1,265

    You know, i don't think i even looked...but i will next time i go there!

    Thanks.

    It really is a great system. Let a little air out each cycle and sink into vacuum evening out the distribution between cycles. It is what I do and like your customer I think the results are great.
    1926 1000EDR Mouat 2 pipe vapor system,1957 Bryant Boiler 463,000 BTU input, Natural vacuum operation with single solenoid vent, Custom PLC control