Let's talk creative uses for temperature and humidity sensors

Nerds let's discuss some creative uses for temperature and/or humidity sensors. First your actual uses than get creative and share with us some creative theoretical uses. Let's get weird and wacky. So get your creative juices flowing and let's automate some weird stuff.

Previous discussions

Lux / Illuminance Sensors

Contact Sensors

Motion Sensors

  1. Temperature sensors do work surprisingly well through refrigerators and freezers. Pro tip - Search eBay for Xfinity Visionic ZigBee. This will lead you to bulk sales of these excellent contact/temp sensors. If you buy multiples they can be had for around $5 USD. Use them as temperature sensors if you wish.

  2. Places them everywhere than you can control you HVAC system using average temperature for the whole house.

  3. Bathroom extractor fan. You can automate this based on the humidity level of the bathroom. When the humidity gets too high it turns on until appropriate humidity levels are reached, than turned off.

  4. AC diagnostics - My AC has been having troubles. I placed a temp sensor directly in my vents too see the temp that the AC is pumping out. Surprised it was only 63 degrees. The coil was freezing up and the HVAC company said I had plenty of refrigerant but I would need to replace my entire A Coil. ($2500 USD) Turns out the coil and outside unit needed a good cleaning and my new air filters were too restrictive. Cost to me to fix it, $5 sensor, $3 filter, asked a little time with the garden hose.

  5. Outdoor temperature monitoring. If using a cheap sensor like mentioned above you can put one outside and not care of it gets destroyed in a few years. This allows me to have my switch bots close the curtains if it's getting too hot out. Additionally it kicks on fans to help circulate the air inside.

  6. (Theoretical) If you can automate the switch to your fans in your range hood you could use a humidity sensor to control them when your cooking. The biggest problems here would be greese and other particulate plugging up the sensor... Anybody have thoughts on how this could be overcome?

  7. (Theoretical) put a temp sensor in your car and you will know when the remote start has warmed your car enough in the winter. Makes me wonder if their is a way to know if the ice is melted in the windshield. Now that would be extremely useful.

I have a 5 temperature probes connected to a smart implant, i have them placed on the hot water supply to my digital bath and shower controllers and the tank outlet.
I then use this as a secondary input to the bathroom lights and fan controls. i also use it to turn on the boiler as i have a unvented cylinder to heat the hot water.

i also have all my indoor temp sensors connect to HSM that will give me a warning if the temp in the house goes above 40 or below 10 deg C.

I've actually been doing this for a year or two now, and haven't had any issues with grease build-up. I've actually been surprised how little grease I've found on even the plastic housing. I have the sensor placed on the underside of the stove hood, but towards the very front so most particulates are either getting sucked up by the fan behind it or are spilling out into the rest of the kitchen before they get that high. The downside to this approach is that the sensor is far enough away from the cooktop that it does take a little while to have the temperature there raise sufficiently above the ambient temperature to kick on the fan, which means I've had a few instances where the kitchen smoke alarm was triggered before the fan kicked in.

What did you use to automate the fans? Mine are variable speed like a dimmer...Did I just answer my own question?

Very nice! That is a great use of temperature sensors!

I built a custom HubDuino ESP8266 solution to add instrumentation to my HVAC Heat Pump. It has 4 DS18B20 temperature sensors to monitor incoming and outgoing air temperatures, as well as high and low pressure refrigerant line temperatures. It also monitors temperature and humidity in my attic, as well as a moisture sensor in the condensate drip pan. It also monitors the thermostat signal wiring, so that I know exactly what the thermostat is actually calling for (I.e. heat or cool, fan on or off, emergency heat strips, etc…)

This data has definitely helped me to identify issues with my heat pump, and to get those resolved before total system failure.

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Are you monitoring the refrigerant lines at the outdoor unit, or once they enter your house?

I finally found a picture of my HVAC Monitoring Board. I monitor all signals in my attic, at the air handler unit.

I use this type of DS18B20 sensor for the air temperatures and refrigerant lines. I had to drill two small holes in my air handler to be able to insert the temperature probes.

https://www.amazon.com/Gikfun-DS18B20-Temperature-Waterproof-EK1083x3/dp/B012C597T0/ref=sr_1_1?crid=3UITM88BL098H&keywords=Da18b20&qid=1658585172&sprefix=da18b20+%2Caps%2C79&sr=8-1

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That is beyond me but since your already working with external temp probes, could you make one using a standard bbq probe? To me that is the holy grail of temp monitoring. Yet nobody makes a ZigBee bbq probe. Best I could do was a Govee wifi one that works with Alexa, but virtual switches just don't work in this case too bring it to Hubitat

Google seems to indicate that it works with the Govee HA integration. So pull it into HA, and then use Home Assistant Device Bridge to bring the temperature sensors into Hubitat.

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I have an ecobee installed with remote sensors in every room. I kick on the bedroom fan for bedtime if the temperature is above a certain value (76). I turn it off at 3AM if it has cooled below a certain threshold (76) and if not I turn it off at 10AM.

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Nothing too complicated about these but they are my favorites!

Screen Shot 2022-07-23 at 12.31.02 PM
Screen Shot 2022-07-23 at 12.30.51 PM

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The fan's wiring is pretty easily accessible so I just wired in a basic Sonoff switch. We never adjusted the fan speed before anyway.

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I use Ambient Weather temperature sensors via the Ecowitt Weather Gateway driver to automate my whole house fan.

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What did you use to monitor the hot tub?

I use temperature and humidity sensors to control my HVAC via indoor dew-point rather than temperature alone.

This has really raised indoor comfort and saved money, because a particular dewpoint can be reached by either decreasing humidity or decreasing temperature. With a two-stage heat-pump, during cooling, running in Stage 1 costs less money and primarily dehumidifies. Whereas running in Stage 2 costs more and cools rapidly. Using a Hubitat-controlled thermostat that permits staging, my automations determine whether it would be desirable to reduce humidity (the major choice in Away mode) or reduce temperature (the major choice in Sleep mode) to achieve the desired dewpoint. In Home mode, it starts out in Stage 1. If the desired dewpoint isn't reached within 20 minutes, it shifts to Stage 2.

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As a hobbyist cheesemaker, I use a bunch of the Aqara Temp/Humidity sensors for monitoring conditions while drying, ripening, and aging my cheeses. Of course I watch the overall temperature and humidity of the "cave" and have alerts for out-of-bounds readings, but the best thing is the small size of the sensors allows each cheese to get its own. I can have multiple cheeses of different styles, each in its own container, with different temp. and humidity requirements, in the same fridge.

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I use a z-wave temp sensor (Homeseer brand, but any would work) to monitor the temperature inside my backup generator. Tells me whether the generator has kicked on in the event of a power outage, and turned itself off after power restored. The latter is actually the most useful as we had a series of power fluctuations that tripped a breaker on the transfer switch, causing the generator to continue running once after the mains power was restored. Doesn't really hurt anything, we found, but at the current price of LP it sure hits the wallet.

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My offering here is nothing new.... A humidity sensor in my garage used with a Kasa smart plug to run a dehumidifier when it gets humid, using Ernie's Smarter Humidity Fan Community App. As an added extra, I use the switch option in the app, then use the Energy Monitoring of my Kasa plug to monitor for lower power usage than expected, triggering a non-committal notification that the Dehumidifier "may be full". Also using @bertabcd1234 's notification proxy, unrelated to this topic, but another great option for those running multiple HE hubs.... I just need to use it more than I do....

That... is.... awesome! Sorry to go off topic a tad but I've only made non-aged Mozz and Paneer as they are kind of "the low hanging fruit" of the cheese world.

I am also looking at making pickles... not sure there is much in the way of anything "smart" needed though - maybe moisture sensor to detect overflows, also temp checking to make sure environment is consistent.

Interesting what you can do with smart devices, thanks for posting this!

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