Measuring voltage or current

Disclaimer: I've very new to the Hubitat world. I've done a bit of bench testing with a switch, outlet, and bulb to get a basic understanding, but haven't implemented anything.

There are a couple of standalone products on the market that monitor the exhaust duct of a clothes dryer. They sense either high backpressure or low airflow to trigger an alert that the duct is getting dangerously clogged. Unfortunately, none of them are smart home friendly, in that they don't have a way to send the info/alert to a HA environment.

I can purchase a pressure sensor that will output either 0-10vdc or 4-20mA, depending on the pressure it senses. I would like to get those readings somewhere where they can be analyzed in realtime, and notify me that it's time to clean the dryer duct. Can Hubitat play a role in this? Is there a way to get the readings "into" Hubitat? Can Hubitat analyze the readings, or pass them on to something else, maybe on a PC, that can do the analysis?


Many Contact Sensors have internal header allowing you to wire something to them that is either Open or Closed electrically.

I have used this to add a (physical) pressure sensor across the connector, which is largely a resistor... as you apply pressure the resistance lowers, eventually reaching the point where the contact sensor makes a report. I want to be clear that the pressure sensor I'm referencing is effectively Weight, not air pressure. I've used the same thing to connect a Float Valve, to measure when my pool needs filling. It's just a magnetic switch in a stainless steel sealed tube. Yet another is an actual switch, a really big button variety, that I use to turn on an outdoor shower. (I was using the pressure sensor under a bamboo grate, so that when someone stood on the grate, the shower would come on... but the bamboo died in the sun and I went old school the 2nd time with a big ol' button.)

What this means is you have to get your air pressure device you use to offer a switch type contact or a resistance that varies by pressure. Then connect it across the header in the Contact Sensor.

One example. I connected this pressure sensor:

My float Valve:


Another option would be to use a Shelly Uni which can sense voltage up to 30v and report it to the hub. I use this to monitor the charge level of some batteries.


Like this idea for the direct measurement and the presumable "incremental threshold" warnings you could establish.

Green<-----life is good
Yellow<----clean the thing the next time I'm in the mood
Red <------do NOT run this dryer until this has been cleaned

In condition RED control the power, which is easy & affordable if it's a 110-115V AC gas dryer.

OK, now I gotta go check my dryer vent :scream:

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Like what you've done here, using these contact sensors in this manner is an underrated opportunity to do more with less. Some of these are really robust devices that SIP power very judiciously. You've expanded on the simple 'remote contact" hack with this resistance idea. Thanks for sharing that !

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The Shelly Uni suggestion got me researching similar devices (that I didn't know existed). I'm leaning towards the Fibaro Smart Implant, mainly because it is a z wave device, and the driver is supported.

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The Fibaro Smart Implant has two inputs that can be used in a variety of ways. I’m fairly sure the inputs can be set to take 0-10V. You could then use the value directly in a rule.

I’ve just checked the manual and can confirm it has 2 x 0-10V digital inputs.