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Thread: Any time delay relay experts here (Ideally with boiler knowledge)?

  1. #31
    Join Date
    Apr 2009
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    Williamsburg, VA
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    5,648
    I personally would not modify the boiler in any way, shape, or form. While it may be electrically possible to achieve what you desire, it's certainly is not recommended, and you know that it isn't the proper way. Some random or fluke failure in your modifications could have unintended consequences that lead to disastrous results.

    The next time the hospital wants you to do something that is questionable, what then? If an elevator messes up, are you going to fix it, or are you going to tell them to call Thyssen-Krupp (or w/e mfg you have) and have it fixed properly?
    Electricians do it until it Hertz!

  2. #32
    Join Date
    Dec 2007
    Location
    NE Nebraska
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    38,492
    Quote Originally Posted by JFletcher View Post
    I personally would not modify the boiler in any way, shape, or form. While it may be electrically possible to achieve what you desire, it's certainly is not recommended, and you know that it isn't the proper way. Some random or fluke failure in your modifications could have unintended consequences that lead to disastrous results.

    The next time the hospital wants you to do something that is questionable, what then? If an elevator messes up, are you going to fix it, or are you going to tell them to call Thyssen-Krupp (or w/e mfg you have) and have it fixed properly?
    Other factors come into play. Probably nothing wrong with replacing worn out or malfunctioning components with same thing. Problem he did present however sounds like something has probably changed and maybe does need a boiler expert to look into it. Still sounds like too narrow of a hysteresis band on the control for some reason is the biggest problem here. Presuming it wasn't always that narrow and something has changed, whether intentional change or not.
    I live for today, I'm just a day behind.

  3. #33
    Join Date
    Apr 2008
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    Ann Arbor, Michigan
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    7,107
    180417-1223 EDT

    Russs57:

    Following is a method that should make you no worse off than you presently are. However, you must determine the root cause of your problem. I suspect that the replacement float switch does not have the level or time hysteresis that the mercury contact float switch had.

    Presently you have contactor failures where the contacts weld together. This will cause overfilling. Failure in one mode of the following method will be no worse than welded contacts, and in the other mode no worse than the float switch alone.

    This method uses a timer that is edge triggered on closure of the float switch, and has a contact closure in parallel with the float switch contacts.

    This timer is powered from the float switch output, basically the same signal as is applied to the contactor coil. Upon powering the timer its output contacts close. These contacts are in parallel with the float switch contacts. This maintains power to both the timer and the contactor coil for the duration of the timer period independent of whether or not the float contacts open.

    At the end of the timer period the timer contacts open, and only the float switch determines whether the motor and timer are powered.

    When the float switch opens the timer and motor are depowered. This resets the timer, and turns the motor off.

    Basically this debounces the float switch contacts.

    .

  4. #34
    Join Date
    Nov 2014
    Location
    Miami, Florida, USA
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    181
    Thyssen-Krupp.....oh I hope you are having better luck with them than I am! We call them thieves and crooks.

    Gentlemen, as mentioned in the beginning, the root problem is water chemistry caused by a bad chemical feed pump. That pump was finally replaced yesterday. A large load that has been added a couple of years ago also hurts matters but that is easily managed. Bad water chemistry creates excessive surface tension on the water and foaming in the boiler.

  5. #35
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    Apr 2009
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    Williamsburg, VA
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    Quote Originally Posted by Russs57 View Post
    Thyssen-Krupp.....oh I hope you are having better luck with them than I am! We call them thieves and crooks.

    Gentlemen, as mentioned in the beginning, the root problem is water chemistry caused by a bad chemical feed pump. That pump was finally replaced yesterday. A large load that has been added a couple of years ago also hurts matters but that is easily managed. Bad water chemistry creates excessive surface tension on the water and foaming in the boiler.
    hopefully the new chemical feed pump will solve the problems you are attempting to fix electrically. As for the elevator, last time I worked for a place that needed elevator repair on that brand, there are only two license shops in the state that would work on them. I believe they sent two techs for an entire day, due mostly to driving distance... and that is not inexpensive. replacing a $10 relay could cost $2,000.
    Electricians do it until it Hertz!

  6. #36
    Join Date
    Jan 2016
    Location
    Earth
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    6,049
    funny boiler story
    in the 80's in an AK village named Bethel I was assigned some work to expand a HS

    It had 2 large steam boilers, firebox type
    I hired a company to clean and inspect to get an idea of servicability
    a tech opened the access portal and climbed in

    next thing I hear him laughing his butt off
    he tells me to get in and look
    in the corner was an ~6" clay model of snl's mr bill, it was fired rock hard
    must have been left by a previous tech
    we left it

    probably still there

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