Furnace flow through humidifier, trickle pad operation & maintenance

As winter begins, the outside air and that in our homes becomes cold and dry. By adding humidity to our house air, it makes our living area more comfortable and pleasant for the family this season.

The two most common humidifiers are:

1) Trickle, flow through or cascade type humidifiers These humidifiers are fed water from above and dribbles water through a metal screen. An electric valve opens at the top to supply water to the humidifier. When the humidistat senses dry air, a solenoid opens the water valve to trickle water down pad. As furnace air moves across the pad, it air picks up moisture. Any excess water drains into a hose to the floor drain, laundry tub, or condensate pump.

2) Drum type humidifiers The drum humidifier has water in a tray of water with a rotating sponge pad on a drum or barrel moving through it. The tray is fed water controlled by a float switch that keeps it full as water evaporates from the drum. As the humidistat senses dry air in the system, a motor rotates the sponged drum in the tray to absorb water. The air moving through the furnace flows across the sponge to gather moisture allowing the moist air throughout the house.

The house needs lower humidity the colder the weather. If the outside temperature is -10 F, set the humidistat to 20%. If it’s 0 F, then use 25% humidity. Most people feel comfortable in humidity between 30 and 60 percent. Too much moisture will cause condensation, mold, mildew, and rot in the house.

Change the pad during the winter if your system uses a lot of water during the season, you have hard water, or have many filter changes.

In the spring, turn off the water supply and humidistat. In the fall, soak the pad in a de-lime solution, or replace it if too clogged.