Dryer Venting for 1984 Condo

The IRC (International Residential Code, section M1502) requires venting a dryer to the outside, and did so as far back as 1997 (the oldest reference I have access to), but most likely farther back than that. However, you CAN use what's called a ventless "condensing" dryer if it is specifically UL listed as such and if there is no access to an outside wall. The "water-filled lint catch basin" is exactly what that would look like, and you will have to periodically empty that water. So it could be that the condo builder provided listed ventless condensing dryers to all of the initial buyers of the condos, rather than install vents to the outside walls. If what's there now is not one though, you can't use a regular dryer there.

Dryer vents are also restricted to being 35ft or less and for every 90deg. bend, that is reduced by 5ft. I don't think a vertical vent (i.e. out the roof) is acceptable, either. So you must either use the condensing ventless dryers or go out a side wall with no more than 35ft of pipe.

Dryers have to vent outside, because if you fail to attach a vent, it will create extreme humidity in the living space, to the point where condensation is assured. The condensation will then cause mold and greatly accelerate rotting and rusting of wood and other building materials. This isn't a "maybe" - it definitely will happen.

The condensing feature amounts to a dehumidifier built into the dryer. It has a little Freon engine that makes an evaporator coil cold. Air circulating through the dryer runs through this dehumidifier before it is reheated.

Of course, the thing about any Freon engine is that there's a cold side and a hot side. Some dryers put the hot side to very good use, using it to heat the air blowing through the clothes, instead of using resistive electric heat. This is a natural "win", and this setup is called a "Heat Pump dryer". It uses vastly less electricity, doesn't add drying heat to the home, and doesn't eject conditioned (warmed/cooled) house air outside causing unconditioned air to be sucked in.

The other thing is, condensing dryer manufacturers know that most dryers sit right next to washers... and washers have a drain. So many condensing dryers are able to dump their condensate into the washing machine drain, negating any reason for you to have to handle buckets of water.

There are 4 modern features designed to save condo builders a lot of money when plumbing utilities to washer-dryer stacks. They are:

• Electric dryers - eliminate the gas line.
• Self-heating washers -- they heat their own water using electric heat, removing the need for a "Hot" water pipe.
• Washers receiving their power from the dryer -- they remove the need for a dedicated 120V circuit in the laundry space
• Condensing dryers -- they remove the need for a dryer vent.

So now they can plumb a washer-dryer space with Cold, Drain and 240V. Done.

If there's one of these "features", expect others. Expect no hot water. Expect no 120V outlets. Expect no gas. Actually see what utilities are present before you go shopping.