A clothes dryer, as shown in Figure 1, is a major home investment. Proper installation of the dryer vent system will extend the life of your dryer, reduce energy costs and keep your family safe from fires.
Figure 1 - Front load clothes dryer
Note: Some clothes dryer manufacturers will void their machine warranty if the dryer vent is not installed according to their instructions.
Additional information on cleaning dryer vents
You have probably invested hundreds if not thousands of dollars in your new clothes dryer. Always follow the manufacturer's specific instructions for the installation of the dryer vent system for your clothes dryer.
If you are replacing an old dryer with a new one, do not assume that the previous dryer vent system is adequate for the new dryer, that you have just purchased.
Dryer Vent Installation Parameters:
- The most direct route from the dryer to the outside of your home, with as few bends in the dryer vent piping, is always the best route. That is why dryer's are usually placed on basement or laundry room outside walls. However, in many cases this is not possible.
- Basement walls that are not designed for direct venting.
- Laundry rooms that are centrally located within a home may have to be exhausted through a roof.
- Apartments that have laundry rooms.
- The maximum distance from the dryer to the outside wall should not exceed 25 feet.
It should be noted, that although flexible dryer vent pipe is available, as shown in Figure 2, it will constrict airflow more than rigid dryer vent pipe, as shown in Figure 3, over the same distance by as much as 25%. That means that if you are using flexible duct the maximum distance to the outside wall should not exceed 18' 9″.
Figure 2 - Flexible dryer vent pipe
Figure 3 - Rigid dryer vent pipe
If you need to run your dryer vent pipe in excess of 25 feet, as calculated with elbows, you should install an auxiliary dryer vent booster fan, as shown in Figure 4. Some models of auxiliary dryer vent booster fans will allow you to extend the vent piping to 60 lineal feet with up to 6 elbows.
Figure 4 - Dryer vent booster fan
Dryer vent booster fans are relatively easy to install, see Figure 5, but it should be noted that they need 120VAC to operate.
Figure 5 - Installation of dryer vent booster fan in attic.
When calculating the amount of vent pipe in your installation use the following equivalent numbers for elbows within your system. Most dryer vent elbows are now adjustable, as shown in Figure 6, to suit any angle. The less the angle, the less the air flow constriction. Adjustable elbows should never be installed with a greater than 90 degree angle.
Figure 6 - Adjustable dryer vent elbow.
- 90 degree elbow is equivalent to 5 feet of piping.
- 45 degree elbow is equivalent to 2 1/2 feet of piping.
Hence, a dryer vent system that has two 90 degree elbows and two 45 degree elbows and travels 6 feet up a wall to exhaust outside of the home has the equivalent of 21 feet of straight rigid dryer vent pipe.