How to Add a Humidifier to a Forced-air System

In this video, This Old House plumbing and heating contractor Richard Trethewey explains how to add a humidifier to a forced-air system.

Steps:1. Screw the humidifier to a wall near the furnace.
2. Cut away insulation from the duct using a utility knife.
3. Position the hole-cutting template onto side of duct.
4. Drill pilot hole through duct, then cut out hole with aviation snips.
5. Secure the humidifier’s steam wand to the duct with self-tapping sheet metal screws.
6. Attach steam hose to wand and to wall-mounted humidifier; secure hose with cable ties.
7. Connect the flexible drain hose to steam wand and to humidifier.
8. Run a copper drainpipe from underside of humidifier to sump pump or floor drain.
9. Cut and solder a copper tee fitting into a nearby cold-water pipe.
10. Run new cold-water copper piping to bottom the humidifier.
11. Have electrician run electrical cable to humidifier and to room humidistat.
12. Turn on water to humidifier.
13. Install air-proving switch in duct.
14. Set the upper limit of humidity on the high-limit switch.
15. Set room humidistat to desired level of humidity in the house.
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