Efficiency reigns in the in-duct humidifier market, and not just because of low operating costs. Avoiding door and window shrinkage that can come with dry air will help reduce leaks, and the enhanced comfort of humidity allows users to turn the thermostat down with no noticeable difference. Think of a humid summer day, when the air feels a lot warmer than the thermostat would have you believe - that's what will be happening inside your home, minus the uncomfortable stickiness, of course.
Not only are in-duct humidifiers efficient, they are generally reported to be the cleanest and quietest of the bunch, in addition to requiring less maintenance. Whole-home humidifiers can be added to most forced-air heating systems, if initial pricing doesn't stop you in your tracks. In-duct units can cost around $100 to $300 or more, plus a few hundred extra for professional installation.
Since many whole-house humidifiers are directly plumbed into the home's water, there is no need for constant refilling; the water flows through an evaporator pad and into the household drain. Cleaning is avoided with models that automatically flush out impurities and have filter pads that collect and trap minerals. The pads usually have to be replaced once a year. Some in-duct humidifiers use warm furnace air to help inhibit the growth of mold and bacteria.
Several newer whole-home systems have automated controls, monitoring the outside air regularly and adjusting output to keep humidity at a optimal level. This prevents over-humidifying effects like condensation forming on windows. As the temperature outside drops, humidity levels in the home should also be lowered, and the right in-duct humidifier will do it for you.
The two main types of whole home humidifiers are flow-through and bypass. They both work on the same basic principle, taking air from the furnace and filling it with moisture before returning it to the ducts to be distributed. Flow-through units are chosen because of ease of use and lack of standing water, but the big downfall with certain systems is they have the potential to waste a lot of water. Look for a model that uses 100 percent of the water taken in.