I don't care how smart your dryer is, if it catches on fire it's not going to do shit.
It's basically 100% detectable. If you are worried about failure of sensor, this is a field where they use sensors in ridiculously contaminated and abrasive environments (material handling, etc).
"Lint" is neither.
(compared to what else we use flexible tube to handle as a material)
So you can simply prevent the fire in the first place. Much more so than pretty much any other appliance.
Do you really watch over your dryer just
to make sure it doesn't catch on fire?
The purpose of me being in the building or nearby is to ensure a correct and timely response. If the fire brigade are called by a real person and asked to attend, they'll know it's not a false alarm.
But when I've seen the fire brigade called by automated systems? False alarms every time. And the police don't even bother to come out to a burglar alarm or car alarm going off - it's got to be confirmed as a genuine alarm by a neighbour or alarm monitoring service.
It is extremely common to have smoke detectors integrated with the burglar alarm. I do not know how common monitored alarms are in private homes, however: I personally can only think of one person I know that has that.
Lint does not catch fire at 140F.
"Task 4. Determine Characteristics Required for Lint Ignition
Lint that accumulates on the heater housing can easily ignite under conditions of a failed high-limit thermostat and a blocked exhaust vent. Lint accumulating near the heater intake can ignite before the high-limit thermostat switches the heater element off. Lint ingested by the heater and embers expelled from the heater outlet can easily ignite additional lint or fabric in the air stream, resulting in additional embers in the dryer system and exhaust vent."
But I can say for sure that those tested dryers are getting much hotter than necessary. Look at the designs on page 6 and 7. Small heater boxes with thin hot coils. If you redesigned it as a big block of heatsink fins with the heating element buried inside, you'd be a lot further away from causing ignition. It would cost more, but in a sub-$100 way.
So I'm unsure at this point. I don't have the resources to test exactly what temperatures are necessary and safe, and which one is higher.
This is how hay bales that are a little moist will catch fire, the digestive process (which is slow but exothermal) of the bacteria in the center of the slightly rotting bale of hay are so well insulated from the outside world by the rest of the hay that the temperature will at some point exceed the ignition temperature of the hay and then you have spontaneous combustion.
Something very similar can happy to driers if the exit ducts become more clogged than a certain percentage.
And let's not even talk about gas fired dryers (does anybody still use those other than dry cleaning services?).
That's why I said "more temperature sensors". It's possible to design a relatively-standard dryer where no part ever gets above boiling, even when the output is completely blocked, giving you a huge margin of error.
Heat in a dryer is all externally applied. It can't build up on its own.
No but sparks that can ignite lint are common risks around operating dryers (both wiring faults and static discharges are issues.)
A smart-ified clothes dryer is more attended to than a conventional one.
>And as a practical matter, busy parents with small children can't defer running the washer and dryer. It needs to finish in time to fold and put away the clothes, and you often need to run multiple loads
I'm one of them. I can't always defer, true enough. But I can often enough.