Having a dryer vent filled with water can be perplexing and annoying.
All of that water and moisture from clothes is supposed to go outside and not trapped in the duct.
I invite you to also read my guide on when a dryer smells like something is burning.
In this guide, I will go over things like…
- How clothing lint can lead to clogs
- Always insulate the duct in attics
- The problems with very long ducts
- Damaged flex vents
1. Dirty Or Clogged Dryer Vent Will Prevent Proper Exhaust
One of the biggest reasons for water in a dryer duct is a dirty or clogged dryer vent. Many homeowners don’t know that you are supposed to periodically clean the dryer vent.
Dryer vents can easily get dirty and clogged due to all of the lint that results from the drying process. The restricted air flow in the duct can lead to a large amount of water in the dryer vent…even totally blocking it. Lint is also a highly flammable fuel source and sometimes results in dryer fires.
Cleaning the ‘lint trap’ before every drying cycle is important — but it simply won’t catch all of the lint — it is just not possible.
When the dryer vent gets choked with lint — it will severely restrict air flow and sometimes even totally block it.
And if your dryer duct isn’t so great to begin with (very long and with many bends) it will just exacerbate the restricted air flow.
According to Energy.gov, a typical dryer load will contain about a gallon of water, and if all of that moisture can’t get to the outside like it is supposed to — it condenses and turns into water.
The best solution is to hire a professional dryer cleaning company (some air duct cleaning and chimney sweep companies also do it) to clean the dryer vent.
2. Uninsulated Ductwork May Lead To Creation of Condensation
Having an uninsulated dryer duct is another common reason for water in the dryer vent.
If you have a long duct run that goes through an unconditioned space such as an attic or crawlspace — the differences in air temperature can lead to water in the duct.
It’s the same thing that happens when you heat up your car on a cold day…sometimes fog and moisture forms on the inside. So if your hot and moist air from the dryer comes in close contact with the cold and dry air from the attic — it can lead to significant moisture buildup in the dryer vent.
And if your dryer vent has a vertical run, the moisture can even fall back down towards the dryer and flex vent.
Probably the easiest solution is to just replace the vent that is in the attic with a vent that has a pre-wrapped insulation ‘sleeve’. However, if you have rigid ducting, I would leave it in place and wrap it in fiberglass insulation.
3. Long And Curvy Duct Will Inhibit Airflow
A too long duct run isn’t likely a main deficiency, but it can contribute and enhance existing duct problems.
If your dryer duct is over 20-feet and has multiple 90-degree turns — you may want to think about changing the duct location. If you can limit the duct run to 5-10 feet that would be ideal.
Read Also: Why Does My Dryer Smell Like Burning?
4. Dips in the Duct Can Cause Water To Pool
If you have a long dryer duct that is secured in the attic or a crawlspace, the dips should be minimized.
When a dryer duct has sags, it allows any condensation to drip towards the low spot, possibly creating pockets of water blocking air flow.
Try to secure the dryer duct with straps so it is as straight as possible with no big dips.
5. Flex Vent Inside The Wall Instead of Rigid Metal Reduces Airflow
Sometimes I inspect houses where there is a flex vent inside the wall or ceiling cavity which is undesirable.
The common flex vent should only be used behind the dryer (from dryer to wall) and it can also be used in attics.
But the vent that is inside the ceiling or wall should only be rigid metal. Rigid metal ducting doesn’t have ridges that can restrict air flow. The ridges on the vent will also capture more lint and slow down air flow.
And even in unconditioned areas, installing rigid UL-approved metal venting is still preferred.
6. Crushed Flex Vent Behind Dryer May Stop Airflow
Sometimes the main problem with water in the dryer vent is the short flex vent behind the dryer.
Frequently when there are dryer duct problems it is because the flex vent behind the dryer is either clogged with lint or crushed. People like to push in the dryer as close to the wall as possible, but this sometimes crushes the flex vent and severely restricts air flow.
A good test is to pull out the dryer vent much father than normal, and see if it fixes the water problem. You may also want to replace the flex vent for a new one or thoroughly clean it.
Read Also: Why Does My Dryer Smell Like Burning?
Test The Dryer Duct From The Outside
Whatever you think may be the problem, and you make a change (such as cleaning the dryer duct) — you should always test the solution.
The easiest way to test the dryer duct is to turn on the dryer, and to check the exterior vent hood for strong air flow.
The air flow at the exterior hood should be robust, it shouldn’t be weak.