Moisture and temperature sensor for compost tumbler

I’m looking for a humidity and temperature sensor, zigbee or zwave, which has a long enough sense wand to stick into a compost tumbler and leave it. Temperature is most important and humidity is a bonus.

A temperature sensor is good for knowing if the compost is doing it’s job, and I’d like to have some data around it to indicate the health

The Ecowitt WN34 has a remote temperature sensor. To use it you would need the GW1000 or GW1100 gateway and use the Ecowitt hubitat app. Here are some links to Amazon and the hubitat app.

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If you can find one, the Iris V3 motion sensor includes both temperature and humidity.

They show up on eBay once in awhile. Probably a long shot. But a small and very useful device.

That's a pretty interesting link, thank you. I'm not excited about having a wifi sensor bridge as part of the mix but it seems like it might be pretty slim pickings out there.

That's an interesting idea. I think I'd have to put the motion sensor itself straight in the tumbler and I worry it would be too humid for the electronics to survive long. I have some of the old Iris v1 motion sensors lying around and they're great...I'm not sure I'd be happy to put one in a compost bin!

And I don't think the v1 does humidity. V2 does temp and motion, but not humidity.

I'd mount it on one of the ends of the tumbler, and try to end with that section of the end on the up-side after a tumble. :slight_smile: I think it would do pretty well - I have a couple v3 Iris sensors outside attached to a garage (protected from direct rain) and they are doing just fine in the heat and/or rain. :slight_smile:

I think humidity would have to be handled separate.

For the environment you have I would suggest a thermocouple, however I know of no easy HA solution. There is the possibility of using these:

Or you can use the FGBS-222 with up to 6 DS18B20 sensors which can be made waterproof but will never be a robust as a type K thermocouple.

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That smart implant is pretty sweet, I had no idea. Thanks for the suggestion.

I don't think I understand the conditioner -- is that just a smarter version of smoothing out the chaos of any analog sensor?

Build one of these and be free of the composting conditions concern and a lot of the maintenance :stuck_out_tongue_winking_eye: Just kidding, ...kinda.

But since you probably already have that tumbler....I agree that consistent monitoring of conditions internal to the pile itself would be a challenge, even tho that's really what we want to know about. Humidity in particular would be a challenging endeavor thinking about those type of sensors and the conditions in the space you are concerned about.

Perhaps one way to approach this is by monitoring the ambient conditions in the airspace or on the tumbler itself as a "scaled indicator" of the internals of the pile. On a hot summer day in the sun all bets are off for getting reasonable readings.

But what if you had a sensor that was encased from the outside weather and tightly coupled to the bottom (outside) of the tumbler where it could be managed (think battery changes). Might say...120F.... on that sensor be indicative of 140+ internal to the pile in the center of the tumbler? I'm not liking that idea even as I finish typing it.

Better to have a 3" probe stuck into the tumbler space which can tolerate getting knocked around by the contents and have that sticking up into the pile from the bottom and attached to an electronics package glued to the outside of the tumbler.

I'll close with the following link
and a comment which you'll likely hear from your local Ag Extension Agent if you ask him or her about it....that "home composting often misses the optimal temperature mark" either because of composition, pile design, or ongoing maintenance. Getting around some of these issues is what has brought the bio-reactor mentioned some serious followers. It's a - design it this way and leave it til it's done approach. You just have to have the space (and all your raw material available at one time).

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Great link, thank you! My design envisions something more like the 3" probe stuck through the tumber wall. Eventually I'd like to get something more complete built up but for the moment I'm stuck playing wheel of fortune in my back yard every other day or so!


Now if you'll excuse me, I'm going out to turn my haphazardly built mess of a compost pile with the front end loader :rofl: Yeah, a few of those bioreactors are on the "To Do (someday)" list. :rofl:

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This conditioner does two things:

  1. increases the the output voltage of the thermocouple to 0 - 5 volts (or 0 - 10). The output of the type K thermocouple is 0V at 0 °C and 41mV at 1000 °C. Hardly enough signal for pretty much any Smart interface to deal with. There are a few other signal conditioning tasks it does as well but the voltage gain is the most importatn.

  2. This particular conditioner (besides being iinexpeensive) electrically isolates the thermocouple from the Hub. This results in a more stable signal and less likely to damage the Hub from ESD etc.

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V1 Iris sensors do not report humidity.

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Thanks for confirming. Man I wish someone had kept making the Iris v2 motion sensor...just about my favorite smart device ever.

They are rock solid.

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I have 2 and I agree.

I wonder why the variation from device brand to device brand. All use the 500 chip (I've not really verified but assume). There is likely reference code. Could the physical board design be so much of a contributor to stability?

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I am totally punishing them. Here's one in a short piece of PVC pipe serving as a gate watch.
One works flawlessly, the other in another location likely sees some confusing heat signatures in the background and doesn't always trigger as well; but still, above and beyond the call of duty in an outdoor application.

I use the Ecowitt remote temperature sensor in my hot tub. Works great, and the wifi bridge integration is 100% local - not cloud. The connection between the bridge and the sensors is in the 400mhz band. I also use their soil sensors.


do you happen to have any caseta devices around? They also use 400mHz, I'm wondering if they have conflicts or not.

In fact I use Lutron Caseta exlusively for switches and I have probably 30 of them. No issues.

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Download the Hubitat app