Dryer vent length,material and maintenance

[jumptrout51]

Technician john63 said

Sometimes it is VERY,VERY difficult to convince consumers of the paramount importance for a clear/clean vent. The shorter length the better (not too short--but that's another story altogether).

[jumptrout51]

How short is too short?
My personal dryers have 14 inch rigid pipe straight through the outside wall.
I have 2 Maytag dryers,one on each side of a Maytag LAT washer.
Both are vented the same. Obviously never had a single clogged vent issue.
Drying time depends upon load size and type material.
All loads dry in 40 minutes or less.
Neither vent has a damper on the outside pipe.

[john63]

How short is too short?
My personal dryers have 14 inch rigid pipe straight through the outside wall.
I have 2 Maytag dryers,one on each side of a Maytag LAT washer.
Both are vented the same. Obviously never had a single clogged vent issue.
Drying time depends upon load size and type material.
All loads dry in 40 minutes or less.
Neither vent has a damper on the outside pipe.

Very short.
If the dryer vent is of the type that goes straight through the wall (approx 12-14 inches) this can cause complaints of:

LAUNDRY NOT DRY AT END OF CYCLE

While this is not as common of an occurrence as vents too long--it is something to be aware of. Frigidaire & LG had discussions about this during training.
In a nutshell--the air flow from the room-to-the-dryer-to-the-outside-vent is too fast. The air drawn into the dryer from the laundry room is not able to be sufficiently heated (not enough back-pressure).

Adding a 90 degree turn to the exhaust vent (or rigid elbow) cures this problem.

I do not see this with every brand of dryer though.
Several times for Frigidaire. Once or twice with the LG.

[Repair-man]

By not having a damper, you are drawing warm air into the dryer during the summer and cold air during the winter when the unit is not running. This raises the humidity level in your house, not to mention costing you more for heating and cooling. I have seen water accumulate in dryer drums during the summer when the customer runs their A/C at full blast. Then there was that 3 foot long snake in the blower....

[john63]

Frigidaire Bulletin
May/June 2004

CLOTHES DRYER NOT PROPERLY DRYING CLOTHES

PROBLEM: Customer complaining of taking 2-3 drying cycles to dry
              clothes. Vent is clear,short and goes directly outside.

CAUSE: Not enough of an air restriction in the exhaust system to
           keep the heated air in the drum.

SOLUTION: Add elbows and additional 4-inch pipe to the exhaust.
                If the exhaust hood has a 4-inch opening,change to
                2 1/2-inch opening. Make sure system back pressure
                does not exceed maximum manometer reading of 0.75
                inches of water column.