I am very new to the space of home automation, and am currently undertaking some research on what is possible with the Hubitat, and would love some input from anyone kind enough to take the time out of their day to help out.
My desired primary usage of the Hubitat is automation of our passive solar greenhouse (PSGH).
What I would like to know is if it's possible with the Hubitat to achieve the following:
Hook up sensors to the Hubitat and get a constant read out on temperature and relative humidity at 2 vertical locations in the PSGH. Should the delta T between the two reach a certain threshold, have it so some fans will turn on to induce circulation. Furthermore, it is desired that once a certain temperature is reached at the top sensor, then it's programmed to automatically open up the vents via a linear actuator. Similarly, it is desired that should a certain temperature be reached, that a thermally insulated blanket go over the polycarbonate glazing of the greenhouse to increase the R value and mitigate the loss of longwave radiation.
Monitor the temperature, relative humidity, and CO2 levels in the root cellar and have alerts set up should any of the above variables get out of a suitable range of values.
From what I have researched, this shouldn't be too much for the Hubitat to tackle. I am however more familiar with weather stations and sensors that are not compatible with the Hubitat.
I am wondering if anyone has experience with a project whereby there is crossover with the above problems and if so what sensors you used and if you would recommend them.
Thanks in advance for any insights you are able to provide!
Furthermore, I'll add that it's desired that the response for the linear actuator/vent is incremental, so that the vents open in proportion to how hot it is outside.
Problem #1 is getting sensor date into Hubitat. If the sensors you have or are assuming you'll get aren't able to inform Hubitat, you won't get past the starting line.
Within that, you say "get a constant read out on temperature and relative humidity" and the word constant is a recipe for overloading the Hub. I doubt the greenhouse needs sub-second response. My guess is that if it adjusted once every 5 mins, it would be pretty amazing.
You may need to create a "Converter" to take your desired sensors and convert them into data for Hubitat. Search here for Hubduino as that's a tiny computer that will take non-compatible sensor data and provide it to Hubitat.
Problem #2 is getting Hubitat commands out to the actuators. It's really identical to problem #1 except the direction of data. If your actuators aren't compatible, you need to convert them to be. Again, the Hubduino project could work as well.
You haven't named your sensors and actuators and I don't think I've ever seen a PSGH.
Once the data is being fed into Hubitat, most of the rest of the problems are doable as you say: "this shouldn't be too much for the Hubitat to tackle. " Once you have the means to see the data (your sensors) and to move your actuators, the remaining is all the fun stuff of detecting nuances in the data and reacting to it.
You are right, constant would be silly...5 minutes would be fine.
Do you have experience yourself with any sensors?
I will note that at the moment, we are in the research phase of this project with regards to setting up the sensors and the automation procedures. I'm not allowed to post links here but if you look up Verge Permaculture on YouTube, we have many videos highlighting the construction of our greenhouse.
What I am getting from your response though is that it is possible to take data from a series of sensors that are incompatible with Hubitat, that's great! We will hopefully be setting up an array of sensors that will also measure photosynthetic active radiation, windspeed/direction, and others. So the more we can link up to the Hubitat via a Converter, the better!
You need to study Hubduino to understand what a converter task is going to be. Although the project is stuffed full of helpful sketches, what's the chance that every single sensor and actuator has been done before? You'll have to know that you can write Arduino comfortably.
There are many compatible sensors, including the Aeon Multisensor 6 that is 6 sensors, including lux, Humidity, UV that might be useful.
@mitch2 Take a look at Ecowitt (www.ecowitt.com). They have all the sensors you would need to control your green house. I use them and they work without any issues. There is a large variety of sensors and very decent price range.
Cheers thanks mate, I'll look into it! I (as many others) really appreciate you putting all those resources out there.
Say if I had purchased other sensors that can take measurements of meteorological variables that Ecowitt cannot, and needed to incorporate other sensors into the mix...how easy would that be and what questions would I need to ask the sales rep from the sensor company in order to be sure that if I do purchase a sensor that I will (at some point down the line) be able to link it to the Hubitat and program some rules. Say for example the insolation was getting a little bit too intense and I needed to program it so that if the solar radiation was getting too intense in the greenhouse I could put drape the shade cloth with a garage door opener-esque mechanism? Is that possible? Also, I'm noticing they do not have soil temperature sensors which I will likely have to source from another company that isn't Ecowitt.
Again, thanks for taking the time to answer this n00bs questions!
Cheers thank you again. I must have overlooked the capability of the soil moisture sensor. Before I drop some stacks on those (will need approx 6) they do in fact measure temperature as well as moisture?
I'm wondering if you can recommend a relay that you have experience with? Thinking for when a temperature threshold is reached and then it will receive the command from the Hubitat to open up the vents via a linear actuator
Cheers and thanks again for all your documentation and support
Buy "dumb" actuators built for the task, and "automate" them with SonOff relays loaded with Tasmota. These little guys are great - they come out of box as a series 120Vac single pole, single throw relay, and if you cut one etch, and move and solder one wire, they turn into a "dry contact relay" to control something where you are interrupting the circuit (such as 12VDC).
You may want to try some genetic temp/humidity sensors before jumping off the deep end into "weather station grade" sensors, as the deltas you are talking about detecting are not subtle at all - they are significant. So, opening or closing the vents and turning on and off the fans one degree "too soon" or "too late" is not going to kill anything.
Many moons ago in the 1970s, I worked with a group on Cape Cod called "The New Alchemists". We did many passive solar greenhouses, and we made "control systems" based on relays salvaged from old pinball machines. One thing I learned the hard way is that one can never have "too much thermal mass".
Does anyone reckon there would be any problems with issuing commands from the hubitat from two different input systems? I am thinking an array of Ecowitt for the inside of the greenhouse and a Tempest Weatherflow for the outside.
Say the inside of the greenhouse as measured by the Ecowitt reaches 30Ā°C (hypothetical number) and there's a command for the vents to open, but there's also a command for the vents to close if the Weatherflow measures a wind speed of 10m/s. I am imagining there is an override function in the hubitat that will prioritize one set of rules over the other. Is this true?
Furthermore, how hard is it to manually override these systems? Say for instance we program the garage door into the greenhouse to open once a temperature threshold is reached, and then close again once the temperature subsides (as per above, windspeed will play into this). Obviously though we will need to operate the garage door to bring materials in and whatnot, will manually operating that stitch the whole protocol up and throw a spanner in the works?
Thanks again for all the help folks! Loving this community
I use node-red to run my hydroponic pumps and lights. This system would allow for the if-then logic you are looking for for the venting system, Their forum has a couple of manufacturing plant engineers who are quite good at helping those with those with questions.
