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Boiler cleaning? Blaa! Who needs it?!

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STEAM DOCTOR
STEAM DOCTOR Member Posts: 1,967
in THE MAIN WALL
Pictures worth a thousand words. Converted gravity system with no bypass to return. Low return temps. Flue pipe crumbled in my hands.

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  • SWEI
    SWEI Member Posts: 7,356
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    Airtight systems

    who needs them?  While you're at it, go ahead and run that cast iron boiler with 100F return temps -- it's tough enough.
  • Gordy
    Gordy Member Posts: 9,546
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    Only if

    The boiler is oversized enough SWEI.
  • STEAM DOCTOR
    STEAM DOCTOR Member Posts: 1,967
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    Sarcastic

    I hope everyone understands that I was being sarcastic. The old(leaking) boiler was piped

    without a bypass, thus insuring very low flue temps (this is a converted gravity system). I am sure that this was a contributing factor to the immense sooting and the poor condition of the flue pipe. Anyway, that boiler has been disassembled and will be removed tomorrow. The new, properly sized and properly piped boiler will be going in within the next few days(I hope). New boiler will have bypass from supply to return,pumping away etc.
  • STEAM DOCTOR
    STEAM DOCTOR Member Posts: 1,967
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    cleaning

    Ironic thing is that there was a boiler brush sitting on top of the boiler. The brush looked pretty clean
  • STEAM DOCTOR
    STEAM DOCTOR Member Posts: 1,967
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    Fitting

    This is a picture of a single fitting that is used for supply and return to the radiator.
  • SWEI
    SWEI Member Posts: 7,356
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    Sarcastic

    I hope everyone understands that we were, too.
  • Gordy
    Gordy Member Posts: 9,546
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    Yes

    Sarcasm ,



    And a boiler bypass is not 100% insurance against low return temps to the boiler.
  • Jason_13
    Jason_13 Member Posts: 304
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    Boiler bypass?

    A boiler bypass will allow much of the return water to bypass the boiler and go back to the supply therefor bypassing the boiler. Reducing the flow in the boiler mill allow cooler water to enter the boiler and reduce condensation.

    Many try to do this with a system bypass that takes hot supply to cold return which is the opposite of what should be done on residential boilers. When boilers had larger water volume a system bypass was a good thing.

    Today with much less water volume in the cast iron boilers we need to reduce the flow into the boiler to get the water temperature up quicker. To quote the late great Gil Carlson " thermal stress and condensation is a result of extremely cold water entering the boiler or coo water at a high flow rate." While we cannot control the temperature with a system bypass we certainly can control he flow rate with a boiler bypass. Adjust the flow to a 20f - 40f delta-t in the boiler and things will work fairly well. Hydronic s Institute states that a boiler bypass sytm will usually give ou 3 times the low in the system than through the boiler. Been using the boiler bypass for years with no boiler issues.
  • SWEI
    SWEI Member Posts: 7,356
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    Thermostatic bypass valve

    Is usually the best option.  ESBE, Caleffi, and LK all have options.
  • Gordy
    Gordy Member Posts: 9,546
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    Thermostatic bypass

    + 1. 100% protection.



    Should add there are a lot of variables that will allow a boiler bypass to work properly, and some that will not. Usually with a mix of emitter types its best to use the thermostatic bypass valve.



    Say you have some baseboard, and rads in a deep setback zone, and boiler is calling on another zone. If the boiler is close to high limit, and deep setback zone calls its a good recipe for boiler shock/condensation. Especially if the boiler is sized properly, and the deep setback zone is large volume.
  • SWEI
    SWEI Member Posts: 7,356
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    Brainless bypass

    works best when the boiler is significantly oversized.  If you size correctly, and actually want to get all the available BTUs out of the boiler, you either need a thermostatic valve or a suitably oversized pump. 
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