By Derim “Mike” Vinca, Owner of A-1 Milwaukee Heating & Cooling · 17+ years in the trade · Updated October 2026 · More HVAC guides
When it is 10 degrees outside, heated indoor air gets very dry. You feel it as static shocks, dry skin and sinuses, and gaps in wood floors and trim. A whole-home humidifier mounted on your furnace adds moisture to the air going to every room, so you are not refilling tabletop units every day. We install and service Aprilaire whole-home humidifiers. Questions? Call or text 414-595-5175.
The three kinds
- Bypass: water trickles over a panel, and the furnace’s warm air carries the moisture through the house. Simple and quiet, with no motor of its own.
- Fan-powered: the same idea with a built-in fan, so it adds more moisture and does not need a bypass duct.
- Steam: makes steam with electricity and puts out the most moisture, whenever the blower runs. The best fit for large or very dry homes, and the most expensive to buy and run.
How much humidity is right
The EPA recommends keeping indoor humidity between 30 and 50 percent. In a Milwaukee cold snap you have to run it lower: if you see condensation or frost on the inside of the windows, turn it down. A humidifier with an outdoor temperature sensor adjusts itself automatically.
What it costs
HomeAdvisor’s 2025 data puts the national average for installing a whole-house humidifier at about $579, with most jobs between $392 and $766. Steam units, and installs that need a new water line, drain or electrical circuit, cost more. Those are national averages, not our quotes; you get a written price after we look at your furnace and ductwork.
Upkeep
Most bypass and fan-powered models need a new water panel every year, at the start of the heating season; AprilAire says its 10, 12 and 35 water panels should be replaced annually. Milwaukee’s hard water leaves mineral scale, and a scaled panel stops working. When the heating season ends, close the bypass damper and shut off the water to the humidifier.
Is a humidifier right for your house?
It helps most in homes heated by forced air. Homes heated by boilers and radiators have no ductwork to carry the moisture, so a portable unit is the answer there. And if your windows already sweat in winter, the house needs ventilation more than moisture, and we will tell you so. If a humidifier on your furnace is leaking, see Furnace leaking water?
What to expect from A-1
We size the humidifier to the house, mount it on the ductwork, connect the water line and the drain, wire it to the furnace and a humidistat, and show you how to set it. You get a written price before any work starts, and repairs are guaranteed for one year, parts and labor. More on our furnace repair, and typical prices for other work in our Milwaukee HVAC price guide.
Frequently asked questions
Will a humidifier cause mold?
Not when it is set right. Keep indoor humidity between 30 and 50 percent, lower during a cold snap, and turn it down if the windows fog or frost on the inside.
Can you add a humidifier to my existing furnace?
Usually, yes, if you have a forced-air furnace with room on the ductwork and a water line nearby. We check both before we quote.
Do you service the humidifier I already have?
Yes. We replace water panels, valves and controls, and if the unit is not worth fixing, we tell you plainly.