Geeze, that's pretty hot. I've never measured a clothes dryer heat output, wouldn't say its very high, The plastic buckles and buttons on my clothes don't melt.
From Google...
The outlet on a clothes dryer, specifically the dryer itself, can reach temperatures between 120°F to 160°F (49°C to 71°C), depending on the dryer type and settings.
Of course, there'll be the lint-gathering factor, lol.
A Thirdreality Sensor...
Maybe affixed outside the pipe would be the best option.
Depends on the dryer. Almost all North American dryers will have a 220 and 110 circuit. On my old dryer I found the 110 circuit that was only energized when the dryer drum was spinning. I put a 110v relay on that circuit and it closed a contact sensor when the relay turned off.
The easiest and most accurate, as already mentioned, is a Home Energy monitor with CT clamps.
No it should be fine. Just a $15-20 temp sensor (ZWave or Zigbee) and then no high current wiring to deal with or NEC compliance questions. I would just double face tape the sensor to outside of pipe or elastic strap it to outside. No need to be inside the pipe, in fact better outside, You are NOT looking for temperature precision here, just detecting a fall off from the high point as an indicator the blower stopped. Just look for a -ve delta of say 15-20 degrees for the trigger. Might be a few seconds lag for pipe and sensor to cool down but you aren't needing msec accuracy either.
Change the sensor battery every year or so when you are doing your annual cleaning the lint from the pipe.....
I would forgo the adhesive and go with some blue painters tape. Easy to remove to replace the battery. That's my solution to my recirc temp sensor taped to a copper water pipe the gets to about 130 F. As you indicated precision isn't important. 10 deg above ambient to trigger rule and a significant drop back for a minute or so to fire a virtual switch that auto resets.
Download the Hubitat app
