I can't help thinking that the reason why the dryer is working better
but tripping the breaker when the duct is going into that plastic vent
box is because the duct length involved is shorter and straighter, but
the humidity in the air is going up.
The dryer duct might not necessarily be clogged. It may be that the
dryer duct is simply imposing too much resistance to air flow.
777sss, in the picture below, can you tell us which kind of flexible
duct you have connected to your dryer and about how long it is before it
gets to the vent cap on the exterior of your house?
(If it's #1, it shouldn't even be used on a dryer because it's a fire
hazard, and ducts like these have so much resistance to air flow that
they'll only work semi-reasonably well if the path from the dryer to the
vent cap is short and straight.)
It could be that the problem with the dryer is entirely due to the
length and type of duct it's being expected to blow air through, and the
tripping of the breaker is because venting the dryer through that little
plastic box is just putting all the moisture from the clothes into the
air, and that increased humidity makes the air more conductive to
I recall getting electrical shocks from the static electricity that
built up on my body when I was a kid and I rubbed my shoes on the carpet
in the house I grew up in. But, that only happened in the winter, and I
subsequently learned the reason was because in winter the outdoor air
comes into our houses and warms up, thereby sending it's relative
humidity way down. In the summer, the indoor relative humidity is
higher, and it's all the water molecules in the air that dissipate the
static electricty on your body into the surrounding air. Dryer air is a
better electrical insulator, and so you have to touch something grounded
to remove the static electricity that builds up, and doing that give you
a small shock.
I'm thinking that with enough humidity in the air and a great big 240
volt heating element in a dryer, you could have enough conductivity
through the air to the metal cabinet of the dryer to trip the breaker.
I know it sounds kinda far fetched, but that's what I keep coming up