Open valve at a specified Outside Temperature?

[dagst47]

Hi all,
I have some “cooling mist” systems (the kind that spray a fine aerosol of water) that I would like to control with my OpenSprinkler. I’ve set one of them up in our chicken coop, so the birds don’t overheat this summer, and I plan to install another one on our patio so that we Humans can enjoy it too!

I’d like to automate the chicken coop sprayers so that they turn On at a specific temperature. They should run for a few hours, or until the temperature goes below the set point. My weather data is coming from a local weather station via the WUnderground (using their API) until I can set up my own weather station. I realize that this is a basic “thermostat”-type of function, but I would like to integrate this into my OpenSprinkler system so that I can comprehensively monitor things like Flow (and therefore Water Use!).

I’m not a programmer, but I’m not afraid to try. Can anyone think of a way to accomplish my goal using the existing (current version) firmware/software? If not, is this a suitable project for an absolute-newbie to programming (ie: a few lines of code vs hundreds of lines), or should I leave it alone and go a different route?

Many thanks in advance,

-D

[ShawnHarte]

I don’t think you will be able to accomplish this using the current firmware…though you could try using something attached to the rain sensor and some clever scheduling to make something work.
I would recommend checking greenhouse suppliers for a thermostatic solenoid, they are often used to cool areas in a greenhouse as well as help with humidity. They are usually not too pricey and would serve their singular purpose well when the health and happiness of your chickens is concerned.

Modifying the firmware could be accomplished without too much work but may be at the expense of other features if you would like to go the easiest/least complicated route. If you would like to add it as a feature perhaps using the current checking capabilities would be feasible. You could attach a thermister to one of the valve positions and run the mister zone based on certain parameters. Or use a digital thermometer of some sort with a pulsed output and read/interpret it through the sensor port. Personally I think a local sensor would be better than running based off of the weather, as the weather is only checked once per hour, though I suppose if you are modifying the firmware this could be changed as well. Just keep in mind the number of API calls you can make per hour and day is limited and could result in restrictions to the service if you exceed them too many times.

I do think it is a novel use of the system, I may try to add it to my forked version of the project. If I do make progress I can let you know, but unfortunately summer is a really busy work season for me.

[Ray]

@dagst47: it sounds like you would want to use a local temperature sensor, as opposed to rely on online weather data.

You are right that this is basically a thermostat type of function. One possible way to make it work with OpenSprinkler is probably as follows:
1) Let’s say the temperature sensor can function like a rain sensor — basically a switch that closes when temperature drops below a certain threshold, and opens when it rises above a certain threshold. In fact, although we mention everywhere that the sensors should be ‘dry contact’, it’s ok if the sensor is actively powered, as long as the output from the sensor is between 0V (logic low) and 5V (logic high). I can almost think of several choices of temperature sensors that would work this way.

2) Let’s say you want to water from 6am to 8am, and contingent on the temperature sensor reading. What you can do is to set a program that starts at 6am, waters for just 1 minute, and repeat every minute for 120 times. So if it’s not interrupted by the temperature sensor, it would water for a full 2 hours. However, if the temperature sensor activates during the 2 hours, the controller will stop watering for the portion where the temperature sensor activates.

So this is basically leveraging the ‘repeating type’ program with very short cycles and many repetitions to approximate what you want.

[Author]

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