Actions
Forum Thread Details
  • Replies 21 replies
  • Subscribers 388 subscribers
  • Views 3709 views
  • Users 0 members are here
Related

I am not a smart person, but I do like performing a bit of science

cstanton

It's too warm in the United Kingdom, so I figured I'd invest in a fan/humidifier combo. 

image

The downside to this hardware, is that it will burn itself out. There's nothing detecting when the water reservoir doesn't have water in it. It's convenient enough, 3 modes to the fan, 3 levels of humidifier, battery, and USB rechargeable. 

So I figured, why not try to detect how much water is left in it with the hardware I have available? I couldn't wait for looking up too much detail or ordering parts from an online store.

I've no idea what I'm doing, so I figured, let's stick a couple of paperclips in there and connect it to an arduino uno.

image

So I read a bunch of values, do some buffering with an array, average them out. I get a very rough sine wave into the analog pin.

And then I notice the pattern, the water's low, the values are higher, the water's high, the values are lower. Setup some ranges, great.

Then I realise what I'm measuring when I turn off the humidifier, the paperclips are picking up the electrical noise from the humidifiers in the water

image


Not quite how I expected to measure if there's water left, but it appears if it's working harder, it's easier to pick up the noise, water isn't the best electrical conductor after all.

Still, I'm sure I should find a better method, but it is a small reservoir, I considered 3D printing something to be able to screw a bottle in to expand it a bit more though.

What do you think?

Parents

  • Is there actually anything to burn out ? What is the mechanism being used to humidify ? 

    A float switch (get creative with that wine bottle cork - screw top ? darn !) or perhaps ultrasonic sensor if you want more detail for water usage over time.

  • in reply to beacon_dave
    beacon_dave said:
    Is there actually anything to burn out ?

    However these humidifier units work I suspect the act of water being in contact with them / flowing through them help to keep them cool, since they heat water and shoot it through an exit hole.  I wouldn't trust leaving it running without water.

    beacon_dave said:
    What is the mechanism being used to humidify ? 

    I don't really want to take it apart to identify how it works.


    beacon_dave said:
    A float switch (get creative with that wine bottle cork - screw top ? darn !)

    The hole at the top's relatively small but perhaps there'd be something to that Slight smile

  • in reply to cstanton

    I wouldn't have expected a steam based humidifier to be USB/battery powered.

    Some of the evaporative ones just blow air through a wicking filter or use ultrasonics or an impeller to create a mist that gets blown out by the fan.

  • in reply to cstanton

    Humidifiers are awesome! : ) 

    The one I have works like Dave mentions, i.e. it only blows cold air through a material that wicks up water from the bottom, i.e. it's ok to run it dry. If your model doesn't have a wick material (the wick is usually replaceable to prevent using mouldy ones) then it could be using a different mechanism, but I'm not very knowledgeable on other methods.

    Parts are getting hard to find, but if you can find a humidity sensor, that would be a good addition just attached to the side of the unit, since the amount of humidity will be easily picked up by the sensor (hopefully!), just for observing your room status and the impact of the humidifier. 

    Regarding adding a bottle, that's a good idea (some mechanism may be needed to stop the water if the reservoir is full, the one I have uses mechanical means, like a float I think (not sure).

Reply
  • in reply to cstanton

    Humidifiers are awesome! : ) 

    The one I have works like Dave mentions, i.e. it only blows cold air through a material that wicks up water from the bottom, i.e. it's ok to run it dry. If your model doesn't have a wick material (the wick is usually replaceable to prevent using mouldy ones) then it could be using a different mechanism, but I'm not very knowledgeable on other methods.

    Parts are getting hard to find, but if you can find a humidity sensor, that would be a good addition just attached to the side of the unit, since the amount of humidity will be easily picked up by the sensor (hopefully!), just for observing your room status and the impact of the humidifier. 

    Regarding adding a bottle, that's a good idea (some mechanism may be needed to stop the water if the reservoir is full, the one I have uses mechanical means, like a float I think (not sure).

Children
  • in reply to shabaz

    Also should mention (you probably already know, but to me it was non-intuitive initially) that you'll want to enable the humidity feature a bit intermittently once it starts getting hotter, to control it to a lower value (whereas originally I thought higher humidity as the temperature rises was better). Meaning, if you ordinarily like (say) 60% RH, then you might want it set to (say) 40% RH once the weather is hot, to keep the dew point value from going high, if we assume dew point to be a good indicator of personal comfort.

    I've never understood why typical home temperature/humidity sensors often don't display the dew point, whereas they have all the information to compute that. 

    The Mijia modules are pretty good (think I've mentioned them in the past), they use a nice Sensirion chip internally, and they are BLE-enabled, so a Pi etc can read off the temperature and humidity, compute the dew point and alert if it is out of the desired range.

    image