Through-The-Wall Dehumidifier Ducting
While it is possible to duct into central HVAC air handling ducts - this article is only focused on simple through-wall projects and does not discuss interfacing with whole house HVAC.
Click here to see a dehumidifier that can be ducted info your central HVAC system.
Why Duct Your Dehumidifier?
In certain situations it is undesirable, impractical, or impossible to place your dehumidifier directly in the area where excess humidity problems are present. Some example situations include:
- You may want to dehumidify a crawlspace, but have no openings into the crawl large enough to accommodate the dehumidifier
- You have a partially finished basement, and do not wish to have the dehumidifier in the finished area due to noise and/or aesthetic considerations
- You wish to create an airflow pattern in the humid area by lengthening the distance between the intake and exhaust ports of the dehumidifier
This article will explain how to duct the intake and exhaust ports of a dehumidifier through a wall. We will also list the materials needed to complete this project. Here at NTSUPPLY - we constructed a false wall to clearly illustrate the ducting process and we photographed the results.
Not all dehumidifiers can be ducted. Some models are specifically designed for ducting and include duct collars on the unit - or specific ducting kits can be purchased.
We picked two of our most popular dehumidifiers for this article:
The duct collars come standard on the Aprilaire unit while the duct kit is an option for the Santa Fe Classic.
Here is a list of materials we used for our ducting project:
- QTY 2 - Airtec Model MVE return/exhaust grille
- QTY 2 - 8" Galvanized Steel Elbows
- QTY 1 - 25' box of insulated 8" flex duct
- Duct Tape
- Long Zip Ties
The steps & illustrations below will describe how we ducted the Santa Fe Classic through the wall. The steps for the Aprilaire 1750 are the same but because of the different shapes of the models - your wall penetrations may be in different locations.
Step 1: Install Duct Collars
Install included duct collars on the Aprilaire 1750 or install optional duct kit on the Santa Fe Classic. The Santa Fe intake collar assembly simply slides into the filter housing on the top of the unit. The exhaust collar is screwed on to the body of the unit through pre-drilled holes with 4 sheet-metal screws (instructions here).
Step 2: Wall Penetrations
Mark and cut your wall penetrations. We used the Airtec grilles for our project because they are incredibly easy to install and they look great. After the hole is cut, insert and secure the grille. Note: remove the 6" and 7" bands on the grille so you are left with an 8" collar for your duct connection.
Step 3: Connect Ductwork
Make duct connections between the dehumidifier and grilles. We elected to use 90 degree elbows to start and finish our duct connection. This gave us a smooth turn to the wall. It is not necessary to do this - the duct can be connected directly to the collar on the dehumidifier and the collar on the grille. The insulated flexible ductwork we used has an inner core and an outer jacket of insulation. Peel back the jacket and duct tape the inner core to the collar - then bring the jacket to the duct. Finish the connection with a zip tie and another round of duct tape. Duct connections to collars on wall grilles are done in exactly the same fashion.
Below are pictures of the intake and the final result. This entire project took us approximately 30 minutes. The Airtec grilles made the job very easy as they simply clamp on to the sheet rock and snug to the wall.
Below are pictures of our Aprilaire 1750 installation. Note the use of a pressure relief vent on the photo to the far right. In this case, the unit is drawing air from the living space, and exhausting into the unfinished space. The relief vent is used to prevent the build-up of positive pressure in the unfinished space.
Alternate Ducting Configurations
It is possible to duct either the intake or exhaust of the dehumidifier and not both. On the left we show an installation where the intake brings air through a duct from the finished space and exhausts dry air into an unfinished space. On the right we show an installation where the air enters the unit in the unfinished space and the dry air exhausts through a duct into the finished space.
Notice that in both cases a pressure relief vent has been added in the wall to prevent any unwanted positive or negative pressure buildup in the space where the dehumidifier is. If your dehumidifier shares a utility room with a furnace or boiler - negative pressure (a vacuum) could potentially draw flue gasses into the space, which is not desirable.
Other Ductable Dehumidifiers
With damper controls and duct collars built-in, the Aprilaire 1750 Dehumidifier is a great model for ducting applications. The Aprilaire 1750, along with the Santa Fe Classic Dehumidifier are our most popular models for ducting. However, they are by no means the only models that can be ducted. With a few accessories and a little assembly, the following dehumidifiers are also great dehumidifiers for ducting:
- Santa Fe Max Dry Dehumidifier
- Santa Fe Advance Dehumidifier
- Santa Fe Compact Dehumidifier
- Aprilaire 1770A Dehumidifier
- Aprilaire 1750A Dehumidifier
- Aprilaire 1730A Dehumidifier
- Dri-Eaz CMC 100 Dehumidifier
WATCH OUR NEW VIDEO ON DUCTING A SANTA FE COMPACT!