My dryer runs forever, gets hot and takes two cycles to dry clothes, and that's with a new clothes dryer. (Electric dryer if that's an issue)
I suspect it's because the 4" dryer vent is 25' long with 5 elbows. I've upgraded the dryer and checked the ductwork for obstructions (none) with no improvement.
Two options I've looked at are,
1) Tearing out the bathtub in the guest bathroom and installing the washer/dryer in that space. I'd end up with about 4' of dryer vent in that scenario. The Mrs isn't real thrilled with this idea even though I told her the old laundry room would have enough space for a whirlpool tub and shower. (and the plumbing is already in place )
2) Installing a booster fan on the vent (most likely scenario).
Will a booster fan work? Any brands recommended if they work as advertised ?