Sump pump monitor emails and raises alarm if water rises

sump_pump_overview

[Matt] literally finds himself in a sticky situation. There’s an oil slick in his sump well. These wells work in conjunction with drain tiles to pump water away from the foundation of a house. Unfortunately the tar that was used to waterproof the outside of his foundation is also washing into the sump and gumming up the works. The system he built will sound an audio alarm and send an email if something goes wrong with the sump pump.

He’s monitoring for two different issues. One technique uses a float valve to sense if the water is too high, signalling that the mechanism controlling the pump has malfunctioned. The other is a current monitor that senses if the sump pump has been running too long (caused by the sump’s water sensor getting stuck in the on position). The one thing he didn’t want to do is control the pump directly as a bug in his code will easily result in a flooded basement. We have the same concerns when considering building a DIY thermostat (an error there could mean frozen water pipes leading to flooding).

Comments

  1. atxinventor says:

    OT: for a moment I had the silliest reaction as what my mind read was that what the sump pump does is monitoring emails. Now, /that/ would be some hack… OTOH, I have had some issues with a sump pump that I could deal with in the way proposed, thanks!

  2. joelfinkle says:

    I’m planning on using Supermechanical’s “Twine” device for this purpose, as soon as their vibration sensor is working. It’s already got a water sensor, and its breakout panel could probably be used for current sensing. Built-in wi-fi and a server which can email, SMS, or send HTTP is also useful.

  3. popeiler says:

    Great build. One thought though- it might be a good idea to use a solid state fluid level sensor rather than a mechanical one for reliability. Your application is pretty critical as far as reliability goes.

    Keep in mind that the density/thermal characteristics of hydrocarbons are different than water, so you will need to take that into account if using a thermal differential device (read: set the switch point correctly)

    • matt6ft9 says:

      I’ve used some of the Maxbotix ultrasonic sensors before. It would have made sense to use one on the project. But, the float I used was simple. (simple keeps the possible failure modes to a minimum)

    • stevebb says:

      If you wanted solid state perhaps try a capacitive probe. The probe itself need not be anything more complicated than a length of insulated wire/plate inside a pipe enamelled wire will work, so to will anodized titanium if you want lots of capacitance change for a tiny change in water level- it’s the thickness of the insulation that determines how much the capacitance changes per change in water level. When there’s water inside the pipe the capacitance between wire and pipe is high, when there’s only air inside the pipe that capacitance will be low, capacitance change is approximately proportional to change in water level. My page on such capacitive probes

      Use such a variable cap as a timing element in an oscillator, and then use the oscillator’s output to detect when f is lower than some threshold to detect high water level.

      Watch out for a voltage spike than can happen when the capacitor is fully charged to say V1 with capacitance C1, and the water level inside the probe is reduced very quickly reducing the capacitance to C2. This is not obvious! The energy stored inside the capacitor remains constant. E=C1*V1^2 = C2 *V2^2 .A bit of mathematical rearrangement gets to V2= V1* sqrt (C1/C2) . now if C2 is 4 times smaller than C1 that’s doubled the voltage. From experience such voltage spikes can destroy CMOS 555s. Found that PUT relaxation oscillators will survive the shocks. Relaxation oscillators have a reputation of being some somewhat awkward to set up correctly, but I’ve found that if instead of providing charging current via a resistor, they had an (approximately) microamp constant current supply to the capacitor they were easy to set up. eg the TLP190B is a series stack of diode type optocouplers, and within certain limits it’s output current will be proportional and far lower that the current fed in on the input side.
      This kind of PUT oscillator also has a capacitor voltage that seems to be a fairly decent triangle wave see my oscillator page at http://wp.me/P2IP1W-s

  4. I just made a similar pump that worked with an arduino GSM shield and it sent an SMS whenever the water level was too low. If anyone is intrested I can show the setup a little more profoundly

  5. grav says:

    I happened to work solving drainage problems for a summer. The general solution is to use two sump pumps, one sitting on a block so it will trigger if the first one fails. Above that is a VERY loud alarm that is really cheap. Generally all this is held within a new, larger crock (plastic not ceramic), and accompanied by a 12v backup battery. That solution with an oil absorber (tubes with stuff in them, used around manufacturing equipment) to be replaced as necessary would solve your issue, but email instead of the alarm so loud it wakes your neighbors would be good

  6. robomonkey says:

    I’m all about building a better mousetrap (sump pump) having had basement flooding issues once myself. I propose an alternative that is easier to acheive.

    Use a product as grav has mentioned (basementwatchdog.com is the one I use) and opto-isolate the critical data you need from that device. To see if your sump has been running too long a current sensor works, but since the floater valve is nothing more than a switch, and most are tandem plugged to provide power to the pump at the receptacle, just add a tap to that, plug in a wall wart, and monitor a voltage over time, rather than needing to do comparisons of current to determine if the pump is running.

    Great idea, I’d be interested to see your final version, but utilizing off the shelf products you can save yourself a lot of headache and have a backup pump to boot.

  7. Ryan05 says:

    Cool Idea but this technology has been out for a long time. NexPump Sump Pump Systems do all of this and a lot more.

  8. signal7 says:

    Even commercial thermostats are not immune to software problems. I set up a monitoring device to watch what my thermostat does this winter and at the same time discovered a bug in the firmware. At random times, it turns on the furnace for one or two seconds when it sees noise from the internal temperature sensor. The thermostat implements a minimum off-time of 5 minutes, but at the same time does not implement a minimum on-time, hence the reason for the bug in the software.

    In this case, it’s not a major issue. Two seconds isn’t long enough for anything negative to really happen. My system is a natural gas fired hot air furnace with a rather complicated control system housed within the unit. Essentially, the exhaust fan will turn on briefly and then the whole system will shutdown before it even manages to ignite the burner.

    There’s a write-up coming in the future on this….

  9. Andy says:

    You could just get a really simple basement water alarm that text messages. We just got one and it’s really easy to install and setup.

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