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Overpressuring a Low Pressure Gauge?

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AdmiralYoda
AdmiralYoda Member Posts: 629
in Strictly Steam
I'm planning out some upgrades in the spring.  Repiping the boiler and drip lines (single pipe counterflow), king valves, a Vaporstat and a low pressure (16oz) gauge.

During my yearly maintenance if I have king valves I imagine they will build more than 16oz of pressure when they blow all the gunk out of my boiler.

What will happen to the 16oz gauge when it goes well beyond 16oz?  Just fine?  Toast?

I suppose I could install a ball valve so it doesn't see the pressure.

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  • KC_Jones
    KC_Jones Member Posts: 5,739
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    You assume the service company will even know king valves and what to do with them. Don't forget a valve on the return piping, in addition to those king valves.

    For a blowdown you will need a valve to isolate the auxiliary controls, namely the Vaporstat and low pressure gauge. Without the isolation valve for them, the boiler will continue to use the vaporstat and not go above it's setting. The boiler will then utilize the pressuretrol as the high limit and allow you to build ~9 PSI as read on the original 30 PSI gauge that would be installed with that control. I would also recommend using unions on all the devices to allow for cleaning of the pigtails.
    2014 Weil Mclain EG-40
    EcoSteam ES-20 Advanced Boiler Control
    Boiler pictures updated 2/21/15
  • AdmiralYoda
    AdmiralYoda Member Posts: 629
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    Thanks @KC_Jones.  This more or less is a curiousity as steam heating is my new hobby.

    I use a very reputable steam specialist from this site for my maintenance.  They are familiar with king valves as they install them on all their new systems.

    The isolation valves are the answer here, thanks!
    KC_Jones
  • KC_Jones
    KC_Jones Member Posts: 5,739
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    My comment was not warranted then, apologies. It's hard to get out of the habit of assuming the contractor doesn't know steam, since we see it so often on here.
    2014 Weil Mclain EG-40
    EcoSteam ES-20 Advanced Boiler Control
    Boiler pictures updated 2/21/15
    ethicalpaul
  • AdmiralYoda
    AdmiralYoda Member Posts: 629
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    @KC_Jones no offense taken, completely understand.  Lots of less than reputable guys out there. 

    I enjoy learning about this stuff and tweaking what I can as a DIY'r.  👍
  • JUGHNE
    JUGHNE Member Posts: 11,062
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    The King valves I come across are from 20 to 80 years old and will not operate because of lack of exercise and use.

    So if you do Kings, it is best to operate them 1-2 times per year.
    This goes for all valves in the building. Especially the stops under lav and WC's. But check for drip at handle after doing so.

    For the low pressure gauge, some have a small ball valve under it and just open when they want to observe the PSI.
    This will protect gauge from vacuum also.

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