Installing a Whole Home Dehumidifier
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Dehumidifiers have a compression cycle much like your typical HVAC system. Air comes in and goes over the evaporator coil; when it hits the dew point, it drops the moisture and flows over the condenser, which reheats the air and sends it through the duct warmer than when it went in.
Bryan has a lot of kids, so between laundry and cooking, there is a lot of water running at home during the day. Instead of using the electric reheat to dehumidify the air as he had been, he decides to install a secondary dehumidifier to control the relative humidity in his house.
Jonathan decides to tie the dehumidifier into both supply plenums: the 4-ton unit AND the 2-ton. Jonathan and Bryan also opt to use wired controls to have a controller in the attic space with a wire running to the return. However, each system is unique; what works for Bryan’s house won’t necessarily work with another house with a different structure (especially when it comes to ductwork and trusses). You may also opt to use unistrut or plywood to support the pan if you need to. Bryan builds a platform at the expense of some extra vibration against the trusses.
Dehumidifier drainage requires a lot of forethought; in this case, we tie the drain into the heat pump water heater’s drain. We take extra care making sure the dehumidifier shuts off when the drain backs up. (Otherwise, it can get messy.) We also make sure we keep our vents nice and high in case anything were to back up in the drain. Like other drains, we make sure that the drain is properly strapped, trapped, and vented with a solid cleanout and pan switch before it ties into the other drain system.
The dehumidifier also has a backdraft damper. Since we want it to open and close easily, we decide to cut it; we’re okay with a little bit of leakage but really don’t want to see the damper get stuck.
The Clean Comfort dehumidifier is pretty quiet and has minimal vibration, and it keeps the relative humidity around 53%, which is a noticeable improvement. We’ve wired the controls with the same typical basic configuration for an A/C unit (although the recommended configuration is to use red for common and blue for hot). Normally, the supply air has more humidity than the return air, but the dehumidifier makes it so that the supply air has lower humidity than the return.
Finally, we check the safeties and make sure the dehumidifier drains properly.
Ultra Aire dehumidifiers: https://www.ultra-aire.com/
Clean Comfort: https://www.cleancomfort.com/
Learn more about the Clean Comfort 98 dehumidifier at https://www.cleancomfort.com/products/dehumidification/whole-house-dehumidifiers/dv098