Ask This Old House plumbing and heating expert Richard Trethewey shows how to control humidity throughout the house all year round. (See below for a shopping list, tools, and steps.)
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Shopping List for How to Install a Whole-House Dehumidifier:
– Whole-house dehumidifier
Steps for How to Install a Whole-House Dehumidifier:
1. In the attic, attach four steel hanging bars and the metal pan from the collar ties. Position the pan very close to the air-conditioning unit.
2. Set the whole-house dehumidifier in the metal pan.
3. Cut a square hole in the hallway ceiling and install a new return-air grille.
4. Attach a flexible return-air duct to the port on the end of the dehumidifier.
5. Secure the duct to the roof framing with plastic straps.
6. Cut the duct to length, then attach it to the return-air grille installed in Step 3.
7. Cut a new supply-air duct fitting into the air-conditioning unit.
8. Connect a flexible supply-air duct to the fitting. Attach the opposite end of the duct to the existing air-conditioning duct system.
9. Run a new PVC condensate line from the dehumidifier to the outdoors.
10. Install the dehumidifier’s filter; be sure to replace the filter every two to three months.
11. Mount a humidistat to the wall beside the existing thermostat.
12. Start by setting the humidistat for 35 percent humidity, then adjust as necessary.
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Homeowners have a virtual truckload of questions for us on smaller projects, and we’re ready to answer. Ask This Old House solves the steady stream of home improvement problems faced by our viewers—and we make house calls! Ask This Old House features some familiar faces from This Old House, including Kevin O’Connor, general contractor Tom Silva, plumbing and heating expert Richard Trethewey, and landscape contractor Roger Cook.
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How to Install a Whole-House Dehumidifier | Ask This Old House