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How to Install a Whole-House Ductless Humidifier

Ask This Old House plumbing and HVAC expert Richard Trethewey travels to Park City, Utah to install a whole house ductless humidifier

1. This job requires working on the water line and making electrical connections. In most cases, it’s best left to professionals.
2. Identify a good location to mount the unit that will allow for proper airflow throughout the house. It’s helpful to keep the utility side of the box near a water line, a drain, and power supply.
3. Shut off the power at the breaker and the water at the main water shutoff.
4. Mount the unit in the desired location using screws and a drill driver.
5. Cut the hole on the other side of the wall where the fan box will go and secure it into place.
6. Make the water connections, starting with the wand through the fan box and working back towards the mechanical unit using copper pipes and fittings. You’ll need to seal all the connections using the solder and flux.
7. Connect the drain lines from the mechanical unit down towards the drain. Use the PVC pipes and fittings and seal it all with the PVC glue.
8. Connect the unit to the water supply line using the copper tubing.
9. Connect the wires that come with the unit to the electrical box.
10. Mount and connect the humidistat in the desired location and set it to the desired settings.
11. Turn the water and the power back on.

Richard installed an Aprilaire 865 Whole House Steam Humidifier with a Wall Mount Fan for Homes without HVAC Duct System. The unit has a higher capacity to account for the vaulted ceilings in the homeowner’s house despite the smaller square footage.

The other tools and materials required for installation, including the copper tubing, drills, and wrenches can all be found at home centers.

After the segment, Richard discussed a different kind of whole house steam humidifier, which is called an AcuSteam Steam Humidifier, which is manufactured by Thermolec.

Expert assistance with this segment was provided by Lee’s Heating and AC.