Whole-House Humidifier Tips

If you have excessively dry air during the winter heating season, you may have found that it leads to a less comfortable environment in your home, with everything from dry skin and nosebleeds to shrinking floorboards.

Portable humidifiers work reasonably well but it can be a tedious chore to continually refill and clean them. If your HVAC system has enough room, you can install a whole-house humidifier.

Whole-House Humidifiers
A typical whole-house humidifier will be installed on the return air duct. An air intake line is installed from the filtered, heated air exiting the furnace, and goes through a damp pad into the return duct.

A whole-house humidifier installation

Controller/sensor. The humidity sensor is on the back side of the unit and
measures the return duct air via a hole in the metal.

The pad is moistened with hot water drawn from a new water line coming from the hot water heater. Water sits in a cup at the bottom and the pad wicks it upwards to where the air flow passes through and into the return duct.

Some tips for operation from a local HVAC company:

1. Change the filter pad twice a year
1. At the beginning of the heating season
2. Halfway through the heating season (approximately February 1st)
3. It's not really worth it to change the pad at the end of the season since the unit will be shut off during the warmer months
2. To turn on the humidifier at the beginning of the season:
1. Make sure the hot water line is on
2. Turn the air flap to the "Open" position
3. Turn on the humidifier control, setting it between 35%-45% humidity (the sensor will measure the humidity in the return duct)
3. Blower mode
1. If the air is too dry even with the humidifier on (for example, if you have another heating source such as a gas fireplace, so the main furnace isn't running enough), the furnace can be set to a blower mode where the fan will run without the heat being on
4. Drainage
1. A clear drain tube can be run from the humidifier into your floor drain. Any water in there should be clear, if it's not you have a problem.
2. Buy a cheap water sensor alarm for your floor to alert you in case of any unexpected leaks.
5. Installation
1. It's easiest to schedule installation in the early Fall, during the break between the cooling season and the start of the heating season
2. It's probably unnecessary to install the outdoor humidity sensor

Changing the Filter Pad

Here's an example of how to change the filter pad on one common model, the Aprilaire 400: