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.
Vent elbows are available which is designed to turn 90° in a limited space without restricting the flow of exhaust air.
Keep exhaust duct as straight and short as possible. Exhaust systems longer than the manufacturer's recommendations can extend drying times, affect appliance operation and may encourage lint build-up on pipe lining.
Most standards call for clothes dryer vents to be no more than 25 feet in length, have few bends, and no kinks. Gas dryers, though, are often permitted to have ducts no longer than 35 feet in length. The more bends in the line that exist, the shorter the overall length should be.
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.
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.
Avoid Long Vertical Runs: If vertical runs are necessary, they should be as short as possible. Long vertical runs can result in greater humidity and lint accumulation, which will reduce drying efficiency. Vertical runs may require the installation of a booster fan to maintain effective exhaust air flow.
A best practice is to have the exhaust terminal located so that the exhaust duct will run horizontally with a slightly downward slope (1/4-inch per foot) to reduce the possibility that condensation will form. At the terminating end of the exhaust duct (at the exterior wall), look for a backdraft damper.
In conclusion, while plumbing vents are traditionally designed as straight pipes, bends are permissible under certain conditions. Proper planning, adherence to local building codes, and maintaining the required slope are crucial factors when considering bends in plumbing vents.
I did some research and found out that while the default is for the vent to come out the back of the dryer, it can also be configured to come out either side!
In summary, while flexible accordion piping may seem like a convenient option for dryer venting, a hard pipe provides better airflow, fire safety, durability, and aesthetics. Investing in a hard pipe may cost a bit more upfront, but the long-term benefits make it a worthwhile investment for any homeowner.
Route the dryer vent horizontally to the home's outside wall. Duct work should pitch 1/4-inch per foot to the outside. This keeps moisture out of the pipe. For basement laundry areas where your ductwork will run vertically to the outside wall, you may need to use 90-degree elbows.
In situations where outdoor venting is not an available option, the vent bucket serves as an efficient indoor solution. It collects lint and moisture, ensuring they do not disperse throughout your living area. It is particularly convenient for apartments or temporary setups.
A short-90 degree is fine on a vent, but not allowed on a drain - as there's not much to get 'stuck' in a vent. Typically a 90 would be used on a vent as its fewer connections and less work, but no issue if you want to use two 45s.
Vent pipes must be installed so they stay dry. This means that they should emerge from the top of the drainpipe, either straight vertically or at no less than a 45-degree angle from horizontal, so that water cannot back up into them.
Plumbing vents can have elbows and be installed horizontally or at an angle. Properly installed plumbing vents should not leak and prevent slow draining, gurgling sounds, and sewer gas odors.
Your plumbing vent pipes must be installed straight on the vertical as this keeps fresh air in and all drains in the house working properly. Vent pipes can be in a variety of pipe styles.
The effective length of a dryer duct with bends increases by 2.5 feet for each 45 turn and 5 feet for each 90-degree curving. If a clothes dryer vent is 25 feet long and has three 90 elbows, which is very common, it would have an equivalent measure of 25 + (3×5) = 40 feet!
It is highly recommended that you do not lay either your washer or dryer on its side. Doing so can hurt the drum or other parts inside. Always move these appliances standing up. Use shipping bolts or transit bolts to keep the washer drum's back secure.
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.
You need to have the shortest run possible to the exterior. You definitely do not want a dryer exhaust line to slope upwards (not even straight pipe) because the weight of the column of air as well as the lint accumulation would really cut down the flow rate.
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.
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.