Electric water level indicator.

Discussion in 'Boilers' started by Jim Holmgren, May 7, 2019.

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  1. May 7, 2019 #1

    Jim Holmgren

    Jim Holmgren

    Jim Holmgren

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    I know there are driffent threads on the subject, though most of them seems quite complex especially for one who does not know a lot about electronics.

    I want something that will switch on a solonid that will lift the check valve of its seat in the feed water pump, when the water level are at the right level.

    Does anyone know how to make sensor like this?
    Maybe I can have two electrodes close together and energize one of them, so when the water touch it will pass the current to the other electrode?

    /Jim H.
     
  2. May 7, 2019 #2

    Brian Rupnow

    Brian Rupnow

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    Buy a cheap, float activated sump pump.
     
  3. May 8, 2019 #3

    rodw

    rodw

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  4. May 8, 2019 #4

    vederstein

    vederstein

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    My boiler uses a spark plug as a water level sensor. The non-pure water closes the circuit and a transistor converts the tiny signal to a higher signal to run a relay. My first implementation of this circuit resulted in a short cycle condition, so I added an off-delay timer.

    ...Ved.

     
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  5. May 8, 2019 #5

    aka9950202

    aka9950202

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    That is brilliant! Spark plugs are easy to get and built for much higher pressures and temperatures. I tip my hat to you sir.

    Andrew in Melbourne
     
  6. May 8, 2019 #6

    Jim Holmgren

    Jim Holmgren

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    Thanks for the advice!

    Spark plugs seems like a great idea!
     
  7. May 23, 2019 #7

    Brian Dickinson

    Brian Dickinson

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  8. May 23, 2019 #8

    Rudy

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    Jim, Have you tested the circuit on steam? My guess is that the steam, moisture and bubbling inside the boiler will create lower resistance over the plug gap and trigger the circuit before the water level reach it. A drop of water will look like it's submerged. Maybe possible to calibrate though.
    If you are into electronics (as I am), I'm thinking the resistance over the spark plug maybe will be high when the water level is low and fluctuating when boiling. However, when fully submerged the resistance will maybe stabilize at a low er level. Then make a circuit to distinguish the stable state to trigger.
    A possible catch here is if you are using destilled water, the resistance will be higher even when submerged. Easy to test though.
    What about a photo cell at the water gauge glass? Maybe the optical difference when the water reaches the photocell will be possible to pick up? I actually made a sensor similar to this once.
    Just my thoughts..
    Rudy
     
  9. May 23, 2019 #9

    vederstein

    vederstein

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    Rudy:

    The issue you mention is what I meant by my original design short cycling. So I added an off delay timer to fill the water level beyond the sensor level.

    The video above was from my prototyping board. In the end I used an Arduino Uno connected to a relay board. I scrapped the transistor because the Arduino already has those electronics included. The Arduino also controls the propane fueled burner, water feed pump, and water inlet valve. The Arduino allows for changes in software to tune the system to my liking. For example, I have logic that prevents the fire from burning unless the water level is high enough. I also have buttons on the control panel to over-ride the logic (like to add more water or force the fire on).

    It's not the prettiest solution, but it works. But then my boiler isn't a model in the truest sense, It's just a boiler meant to run my engines somewhat safely.

    ...Ved.
     
  10. May 24, 2019 #10

    bluejets

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    Why not use a normal everyday float switch.
    Simple and virtually trouble free and no batteries required.
    Example below.

    https://www.ebay.com.au/itm/Liquid-...36e5ca14b343a2ba83020951a5a8ce&frcectupt=true
     
  11. May 24, 2019 #11

    DickG

    DickG

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    An electronic boiler water level unit is very simple to make - even if you have no electronic knowledge. Hundreds of them are in use over here in 16mm and G1 steam locos. There are versions for one or two electrodes and the electrodes are quite straightforward turning exercises.
    DickG
     

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