While not a DIY project, home technology expert Ross Trethewey shows a homeowner the basics of having a whole-house humidifier installed to help solve their winter-specific dry air issues.
Your Heater is the Problem
Winter can be a tough time for controlling the humidity in your home. Unlike summer, where air conditioning systems actually handle the bulk of the humidity control, heating systems actually cause the issue. As air is heated, it wants to escape the house, pulling in cold air behind it. That cold air is dry and continues to sap the moisture from the air. While it should be between 30% and 60%, some homes might reach humidity levels as low as 15%, causing dry skin, static, and other issues.
Pro Tip: Richard Trethewey, This Old House heating and cooling expert, explains: “The air passing through a forced-air furnace is heated to as much as 500 degrees Fahrenheit, so it’s no wonder that the air feels bone dry after the furnace has been operating for a few weeks.”
As Richard Trethewey has noted in This Old House Magazine, “Humidity—the amount of moisture in the air—has a huge impact on people’s comfort. A relative humidity of 30 to 40 percent is considered ideal, but any time you heat or cool the air inside a house, you change humidity levels as well.”
A Whole-House Humidifier is the Solution
A whole-house humidifier can solve the problem. These systems are installed in the trunk of the HVAC system and work to emit moisture into the air after it has been heated within the coil. This allows the heating system to maintain comfortable levels of moisture, fighting the cold, dry air cycle.
Pro Tip: Ross, an HVAC technician featured on Ask This Old House, recommends sizing the unit based on your home’s square footage, air leakage, and exhaust fans: “That’s based on the square footage of your house, the air leakage of your house, your bath fans, et cetera.” He also advises setting the humidistat to 35% and making only minor adjustments during the first winter: “One thing we don’t want to do is play with it too much and turn it up too much, because if you turn up too much, you could actually have a rainforest in your house.”
In a typical installation, the humidifier is mounted on the side of the ductwork, and the HVAC fan moves the moistened air through the ducts, out through the registers, and blends it throughout the home. For houses with ducted systems—which is how most houses in America are heated and cooled—the integration is straightforward.
What Do You Need for a Whole-House Humidifier?
There are a few things you’ll need for a whole-house humidifier system. As far as parts go, you’ll need a humidifier system, a humidifier wand, and a humidifier controller. These items are installed near the heating system, with the humidifier wand being installed in the air ducts.
Other items you need to install a whole-house humidifier are at least 6 feet of straight trunk run, a nearby source for electricity, another source for fresh water, and a nearby drain for condensation and overflow.
How Does a Whole-House Humidifier Work?
Whole-house humidifiers are relatively simple in theory. The system is installed near the main heating system, and inside the humidifier is a water tank. The tank has electrodes at the top, and as the water rises and touches the electrodes, it vaporizes and becomes steam. The steam then travels through a pipe to the humidifier wand, which is installed in the ductwork on the supply side of the heater.
As the thermostat in the home senses low humidity levels, it sends a signal to the humidity controller. The humidity controller throttles the humidifier on and off, controlling how much humidity is pushed into the ductwork and dispersed throughout the house.
Long-Term Maintenance of Whole-House Humidifiers
Maintenance for these systems is relatively simple. All that service requires is replacing the tank and cleaning the electrodes every two to three years. This removes collected scale and allows the humidifier to work more efficiently, keeping the home comfortable for years to come.
Pro Tip: In a This Old House project, Ryan explained that newer steam humidifiers have a built-in self-cleaning feature: “This unit will sense the amount of minerals that build up in the cylinder. And if it gets to be too high, it’ll flush the cylinder.” This automatic flushing helps keep the system clean between scheduled maintenance visits.
Resources
Ross Trethewey recommends a whole house humidifier for a homeowner experiencing very dry winters.
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