The most common place to vent your dryer is horizontally through the exterior wall near the dryer, which is the ideal placement. Other common locations are through (but not into) the basement or the attic/roof. For most dryer models, you can't run the exhaust duct more than 25 feet from the dryer to the exhaust port.
DO NOT terminate dryer vents in crawl spaces or attics. Dryer vents that terminate in crawl spaces or attics allow for moisture to deposit and encourage mold growth and health hazards. Dryer vents must terminate outside of the building.
Dryer Vent Locations
The best place is usually an exterior wall, which allows the duct type to be as straight and short as possible, minimizing lint buildup and reducing the fire hazard.
The exhaust duct should be rigid metal 4 inches in diameter and no more than 35 feet in length or as specified by the duct manufacturer. This length should be decreased by 2.5 feet for every 45-degree bend the duct makes and 5 feet for every 90-degree bend the duct makes.
Dryer vent should go through the sidewall of the house. The shortest distance as reasonably possible with the fewest numbers of elbows. (Because each elbow will add friction which will act to impede flow.)
M1502.
The maximum length of the exhaust duct does not include the transition duct. This means that vents should also be as straight as possible and cannot be longer than 35 feet. Any 90-degree turns in the vent reduce this 35-foot number by 5 feet, since these turns restrict airflow.
But you must bear in mind that if you are going to purchase a vented tumble dryer you need to ensure that you place the dryer near an external wall or window. This then ensures that you can have a vent fixed through the wall to allow the moisture to escape outside.
Turn on the dryer to test the flow of the dryer vent installation. Go outside and see if the louver or flap on the vent hood is operating. If there is no airflow or airflow is weak, re-check all your duct connections.
Termination. The exhaust duct should terminate outside the building at least 3 feet from any building opening, and at least 10 feet from an air conditioner or heat pump condenser (reference).
Ensure the window is open enough for hot air to escape, but remember, this isn't a safe long-term solution and can still pose fire and moisture risks. Indoor Venting Option: If you can't vent outside, you can use an indoor vent kit.
Be sure to keep 90-degree bends to a minimum. Every 90-degree bend is the equivalent of ten feet of vent run. Never install a dryer vent which has a bend greater than 90 degrees. Sharp bends restrict airflow and will lead to excessive lint buildup.
Some dryers can exhaust beyond 25 equivalent feet without a booster fan. Dryer Duct Booster Saves significant energy - reduces drying times 50% or more. Reduces lint build-up, dust & fire hazards by maintaining proper velocity in duct runs up to 150 equivalent feet.
Venting a dryer through the roof causes issues with moisture control for a few reasons. First of all, moist warm air condenses back into a liquid if it makes contact with cold attic air. That can cause the water to back up and block your vent. Even worse, it may spill back out into your laundry room.
In conclusion, while traditional electric dryers do require a vent to the outside to expel moist air, advancements in technology have brought ventless options to the market.
Answer Almost all clothes dryers locate the exhaust port in the same location; at the bottom of dryer's rear panel and in the center. With that in mind, The Dryerbox is properly installed if set right on the bottom (sole) plate (2x horizontal member at bottom of wall framing) just about touching the rough floor.
The flexible nature and expandable configuration allow most installs to occur without any modification to the duct or the wall penetration. A pair of jumbo zip ties and you're good to go…at least for a few months until all of the internal bumps and ridges begin to clog with lint.
Codes and Standards
In the United States, most home inspectors refer to the International Residential Code (IRC) M1502 for dryer venting. However, some states may have additional regulations. The International Mechanical Code (IMC) 504 also includes extensive clothes dryer requirements.
As with heat pump tumble dryers, condenser dryers do not need an externally vented hose, meaning you will be able to install your appliance anywhere in your home. However, a condenser dryer does need a constant supply of cool air to function.
Do all dryers "vent-out" of the dryer appliance in the same place? And where is that? Answer Except for the stackable combo washer/dryer units and some European units, most dryer appliances exhaust through a 4" port at the very bottom of the rear back panel, and it is located in the center measured from side to side.
Improperly installed dryer vents can lead to airflow restrictions, longer drying times, increased energy consumption, and overheating. Additionally, they can cause lint and moisture to escape into your home, leading to mold growth and potential fire hazards.
Ideally, your dryer should have exhaust vents that lead outside to keep your laundry area clean and less humid. The most common place to vent your dryer is horizontally through the exterior wall near the dryer, which is the ideal placement.
504 requires a dryer exhaust to be vented to the outside. This has been in the code for many years. There is an exception for a ventless dryer but the dryer has to be listed and labeled. Also the room where the listed and labeled dryer is installed shall have a 70 cfm exhaust fan and a floor drain.
Air-vented dryers draw air from the room in which they are installed, heat it and lead it through the humid clothing in the drum to evaporate the moisture. The humid air is then expelled to the external environment. Air-vented dryers thus require an exhaust to the outside, making them less practical.
Energy use
We've previously found condenser dryers to not be very energy efficient. Along with older vented varieties, they use around three times more energy to dry a load than their heat pump counterparts. This means vented and condenser dryers cost more to run in the long term than a heat pump.