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  1. #1
    Join Date
    Mar 2007
    Philadelphia PA

    Default steam boiler doesn't require "blowdown"?

    I inspect maybe 3 steam boilers a year. The one I looked at this morning was 2 years old and appeared to have an automated device for keeping the proper level of water in the boiler.
    But...the owner tried to tell me "you don't have to do anything" when I brought up the subject of "blowdown", i.e., regularly draining a certain amount of water from the system to remove the sludge that builds up from all that boiling.
    This is B.S., right?

    Inspection Referral SOC
    "There is no exception to the rule that every rule has an exception." -James Thurber, writer and cartoonist (1894-1961)

  2. #2
    Join Date
    Mar 2012
    Lansdale, PA

    Default Re: steam boiler doesn't require "blowdown"?

    Systems with an electronic low water level switch do not have the typical blow-down valve. You still should drain water from the boiler using the drain valve.

  3. #3
    Join Date
    Mar 2014
    Ozark, Missouri

    Default Re: steam boiler doesn't require "blowdown"?

    Pretty much all steam boilers require a blow down at regular intervals, although some have an automatic blow down.

    The bottom blow-down removes the minerals that precipitate from the water (scale), and also, the wetted surfaces in the boiler, piping, and radiators, etc. are often ferrous metals and will dissolve over time and form mud. You can easily cut a steam boiler's life expectancy in half by not blowing down the mud drum. On high pressure boilers (over 15 psi) it is require by code. Most HP boilers are blown down every shift. It is much better than having a hot-spot form which can lead to boiler failure.

    I was talking about a bottom blow-down where the sludge settles. Many boilers have automatic surface blowdowns to remove oil and other floating contaminants on the surface of the water. These are not needed on residential boilers, and are not a substitute for the bottom BD.

  4. #4
    Join Date
    Dec 2008

    Default Re: steam boiler doesn't require "blowdown"?

    The Auto Fill valve should be operated every 6 months. Reasoning is that the valve may stick over time. Taking 1 or 2 gal off the system will flush the valve. Furthermore, you can listen for the valve opening to be sure it is functioning. Some you can actually see the mechanism working. The Auto Fill may be automatic but it is not maintenance free. That is if you want a boiler that will last 30,40 or 60+ years....

    Then bottom sludge.
    The removal of the buildup in the bottom of the boiler, like Scot describes, is something different than the Auto Fill Valve.

    Last edited by Garry Sorrells; 08-02-2014 at 05:54 AM. Reason: Reread origional question 2 parts.


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