Depending on where you’re from, you may have a positive view of ventless dryers or a fairly negative one. Ventless dryers are a somewhat new technology that has the added advantage of not needing ventilation. Some think that ventless dryers are too good to be true.
It is true that ventless dryers have their fair share of pros and cons but some of the popular arguments against ventless dryers aren’t actually accurate at all.
Listed and labeled ventless dryers aren’t against the code. They don’t increase a room’s humidity or the risk of mold growth. Water vapor is condensed and drained. They produce and collect less lint and run colder, posing a lower fire risk. Heat pump units have longer dry times but are very energy efficient.
The Law/Code Prohibits Ventless Dryers
When consulting the International Residential Code (IRC), little is said about ventless clothes dryers.
Most sections in the IRC related to clothes dryers mention vented dryers and regulate where the exhaust can go, the length of the ducting, and more.
Without further inspection, it may seem that the IRC does not allow ventless dryers because their exhaust moisture is not conveyed to the outdoors.
This is not true, however, because the IRC actually does mention ductless models as exceptions in two specific regulations.
Section M1502.2 of the IRC states:
“Dryer exhaust systems shall be independent of all other systems and shall convey the moisture to the outdoors. Exception: This section shall not apply to listed and labeled condensing ‘ductless’ clothes dryers.”
Another example of the IRC mentioning ductless models as exceptions is below.
Section M1502.4.8 of the IRC states,
“Where space for a clothes dryer is provided, an exhaust duct system shall be installed. Where the clothes dryer is not installed at the time of occupancy the exhaust duct shall be capped or plugged in the space in which it originates and identified and marked ‘future use.’ Exception: Where a listed condensing clothes dryer is installed prior to occupancy of the structure.”
These exceptions mean that ventless dryers are allowed and don’t need to be vented in order to be compliant. Their compliance is, however, dependent on other factors; the condensing clothes dryers must be “listed” and “labeled.”
To be listed and labeled means that the product has been officially recognized with a label or identifying mark by an organization that specializes in product evaluation.
This means that your ventless dryer cannot just have “ventless” in the name and be considered ventless. It must be recognized and labeled as such by an official organization.
The importance of this is that the products will have to conform to a certain standard that ensures that lack of vent will not compromise the safe utilization of these units.
Ventless Dryers Increase Indoor Humidity/Mold
It is a common misconception that ventless dryers increase indoor humidity and mold because they do not have vents through which to expel their exhaust. This is because it seems to be assumed that all of the water that is removed from the clothing is then released from the machine as water vapor.
In actuality, the moisture from the clothing is evaporated by warm, dry air. This air is then cooled inside the machine. The evaporated water condenses into a liquid and is drained out of the dryer in a hose or collected in the water container to be emptied later.
Ideally, there should be little to no moisture exiting your ventless dryer, either as a liquid or as a gas, except for that which is drained or collected in the tank. This means ventless dryers don’t significantly increase the humidity in the room they operate in.
When it comes to the matter of whether ventless dryers cause mold, the reality is that they do not tend to have this result, especially if there is sufficient ventilation in the area (sufficient being a door or window that is opened regularly). This is because they don’t add to the humidity in the room.
We have already established that ventless dryers are permitted by the building codes. This would not be the case if they increased humidity because of the health and safety concerns linked to increased moisture in the air and the growth of mold.
Lint Fires Are More Likely With Ventless Dryers
The assumption that vented dryers are actually less prone to fires than ventless dryers because they expel lint through their vents is an incorrect one. In actuality, ventless dryers are less prone to fires. Let’s look at why.
- Lint is not freely sprayed around the house by these appliances. There are lint traps in ventless dryers that catch the lint. It is important that these are cleared regularly, but doing so is not difficult or time-consuming. Because the lint is caught, it can’t accumulate in the corners of a room like little piles of kindling.
- Ventless dryers actually produce less lint because of the lower operational heat, which is less likely to damage fabric fibers and cause them to break off.
- There are no vents in which lint can accumulate unchecked. The lack of vents also eliminates a major source of dryers overheating. When the vents become blocked, usually with the flammable lint, it interferes with airflow and heat builds up. Should it build up to a point at which lint can ignite, there is also a plentiful supply of fodder.
- Heat pump dryers do not have heating elements. Overheating dryer elements are a common ignition source for lint fires.
- The lower operating temperature of, in particular, heat pump dryers, means that they are further away from the ignition point of lint and a lot more has to go wrong for this point to be reached.
Longer Drying Times Means Greater Cost
The assumption that ventless dryers have longer dryer times and, therefore, cost more to run is partially true and partially untrue.
Condenser dryers, one type of ventless dryer, are more similar to vented dryers in terms of energy consumption and operational temperatures, so they take the same amount of time and energy to dry a load as a vented dryer. However, they usually have a smaller capacity, which means that you need two cycles to dry one washer load.
If we look at heat pump dryers, the best type of ventless dryer on the market, we find an interesting paradox.
The heat pump ventless dryer takes a lot longer to dry a load of washing than vented dryers but they use significantly less energy, and so cost less.
A heat pump dryer can run as long as an hour and a half for a load that would take only 45-50 minutes for a vented dryer, but to do this, they use 40-50% less energy than the average electric vented dryer.
This is because of the heating mechanism used (heat pump as opposed to heat element). You can read more about this mechanism in What Is a Heat Pump Ventless Dryer.