Tumble dryer condenser boxes are ineffective. They also contravene the IRC, which says that, with the exception of approved ductless models, dryers must vent through the outside. Venting outdoors prevents moisture and heat damage to the home and ensures that the dryer does not affect indoor air quality.
Vented dryers are designed to expel hot, moist air produced by the dryer to the outside of the home through a hose. Condenser boxes like the one below aim to make vented dryers functional without that hose leading outside.
If you cannot or do not wish to vent your dryer outside, unfortunately, condenser boxes are not the solution. In this article, I will tell you why this is the case and provide you with an alternative and much better solution.
Most People Think Condenser Boxes Are Ineffective
It is important to remember that vented dryers are not designed and built to be used with a condenser box. These dryers are made under the assumption, and even the condition, that their troublesome air will be expelled outside of your home and not into a small box inside.
The consensus on condenser boxes across the web is critical. Many people complain of the minor yet annoying problems that come with trying to use two devices together that are not made for each other.
For some users, finding a condenser box with a hose that fits the dryer can be a burden. A hose too small will not fit, and a hose too large will allow the dryer’s air to leak through.
Other users feel that a small box simply cannot trap all of the air a dryer needs to expel. Many share stories of walls wet to the touch and rooms noticeably humid after only one cycle using a condenser box.
The vast majority of reviewers across the web recommend simply venting the air outside (even if it’s just through a nearby window) or buying a condenser dryer instead.
While negative user feedback might be enough to deter some people from utilizing this technique, there are others who might still like to give it a try. However, I don’t recommend this because, on top of being ineffective, condenser boxes are also a building code violation according to the International Residential Code (IRC).
Building Codes Require Dryers to Be Vented
Section M1502.2 of the IRC states:
“Dryer exhaust systems…shall convey the moisture to the outdoors.”
Just in case there was any confusion with this one, the IRC reiterates this point in Section M1502.3:
“Exhaust ducts shall terminate on the outside of the building.”
So technically, dryer condenser boxes are not in compliance with the residential codes applicable throughout most American states and other parts of the world.
This section goes on to mention that dryer vents have to be at least 3 ft away from any openings into the house, such as windows, which means that running the hose out of a nearby window is not going to cut it.
International Residential Codes are only model codes that can be adopted into law by a particular jurisdiction. In other words, it is safe to say that using a dryer condenser box is not going to land you in jail.
Still, following building codes is in your best interest.
The IRC provides the foundation on which insurance companies assess risk. Compliance or lack thereof with building codes will affect your insurance premiums. A home not in accordance with the codes designed to keep it safe will be considered a higher risk.
Non-compliance with building codes will also probably decrease the price at which you can sell your house. Now, the dryer is a movable appliance as opposed to a fixture, so it’s not going to have the same impact as non-compliant wiring, for example.
However, houses compliant with the codes are less likely to see damage (that’s what building codes are largely for).
So, if a buyer sees your condenser box, they will start to wonder about hidden damage and other places where you might be violating the building codes. This can make them hesitant to purchase your house or they might try to drive the price down.
Moreover, let’s not forget the fines that contravening the building codes can incur.
Overall, using a condenser box with a dryer that is supposed to be vented outside has the potential to cost you a lot of money.
Exception: Those Designed to Be Ventless
There is an exception to the statement in Section M1502.2:
“listed and labeled condensing (ductless) clothes dryers.”
This exception exists because condenser dryers are able to effectively control their air through recycling.
Instead of getting rid of hot and moist air through a hose like vented dryers, condenser dryers send their used air over cold condenser coils, which cause the moisture in the air to condense.
The condensate collects the moisture in a reservoir or pumps it out, and reuses the dry air.
These kinds of dryers (ventless) also have smaller load capacities than their vented counterparts. This contributes to why they are considered safe to use because less wet clothes in the dryer means less moisture released during a cycle.
Condenser dryers are an exception in the eyes of the IRC because they, even though ventless, safely control their moisture and heat emission.
Practical Drawbacks of Condenser Boxes
While building codes can sometimes seem hyper-technical and distant from their safety objectives, it is easy to see why they denied condenser boxes’ acceptability.
Condenser boxes’ lack of efficacy will more often than not damage your home, and, which is more, cause a safety hazard.
Water in the wrong places is destructive. The moisture that is not trapped by the condenser box will end up on the floor around it, on any walls nearby, and all over the room through humidity.
Any types of walls, with very few exceptions, exposed to water for too long will discolor, soften, and/or crack. Unless you have experience with drywall, you can expect the repair to cost you $50 to $75 per square foot. And prices are usually higher for other kinds of walls.
Tile, hardwood floors, carpet, manufactured and natural stone, and most other floors are also highly susceptible to damage from the use of condenser boxes. Along with the damage, wet floors also become slipping hazards.
High levels of moisture on surfaces also promote mold growth, which gets into the air, making it odorous and toxic to breathe.
Speaking of toxic air, if you try to use a condenser box with a gas dryer, then you run the risk of introducing carbon monoxide into the room and the house. I don’t need to tell you how dangerous this is!
Some condenser boxes are so ineffective that they render the room they are in noticeably more humid—an obviously less critical drawback but worth considering.
Rather Buy a Condenser Dryer
If using your vented dryer with a hose leading outside won’t work for you, the best solution is purchasing a condenser dryer. Condenser boxes, while slightly better than simply venting your gas or electric in dryer inside, simply are not effective enough in trapping moisture.
You might directly decrease your insurance premium and increase the sale price of your home by buying a condenser dryer instead. You will avoid damage to your home and health and save yourself from the headaches that come with condenser boxes.
You can also opt for the slightly more expensive but highly efficient heat-pump dryer, another variation of the ventless dryer, and a fantastic option.
Although a small box only costing $10-$25 that is easy to install and claims to solve your dryer problem is enticing, it is most likely only going to further your troubles.