To make the dyer more efficient you can buy an inexpensive heat diverter and install it in the exhaust duct of electric dryers only not gas dryers you ll save about 50 worth of heat per load in the winter.
Outside dryer vent on roof.
Considering that back pressure higher than 6 wci is generally recognized as inefficient you can see that venting through the roof with non dryer specific vents is immediately problematic.
Vent a dryer through the roof only as a last resort.
Connect your dryer to its power sources and turn it on.
Cleaning lint buildup from roof vents is difficult and nesting birds and squirrels often find roof vent caps irresistible.
Unlike the vents shown above left the dryerjack affects airflow by less than 01 water column inches of pressure.
Vent dryers outside venting the dryer outside in cold weather wastes a lot of heat.
You can now replace the outer vent cover.
Dryerjacks are the first roof vents designed to meet the more stringent venting requirements of dryer exhaust systems.
The problem with attics the attic is usually colder than the rest of the house during the winter and that can create a problem for a dryer vent.
But we don t recommend it for two reasons.
Check with your appliance dealer or local building inspector for recommendations about the best roof vent cap to use.