Minnesota winters are brutally dry. Forced-air heating makes it worse — when cold outside air (which holds little moisture) gets heated to 68–72°F indoors, its relative humidity drops to 10–20%. That's drier than the Sahara Desert in summer. A whole-home humidifier attached to your furnace adds moisture to the air as it circulates, maintaining comfortable humidity levels throughout your home. Here's what you need to know.
Why Minnesota Homes Get So Dry
Cold air can hold very little water vapor. When 0°F air at 70% outdoor relative humidity gets heated to 70°F indoors, the relative humidity drops to roughly 8–12%. Your furnace is constantly pulling in cold, dry outdoor air through infiltration and combustion — and heating it into extremely dry indoor air. The result: static electricity, dry skin, cracked lips, nosebleeds, wood furniture cracking, and hardwood floors gapping.
Types of Whole-Home Humidifiers
Bypass Humidifier (Most Common)
Connects between the supply and return air ducts via a bypass duct. Water flows over an evaporator pad; warm supply air passes through the pad, picks up moisture, and returns through the bypass to mix with circulated air. Simple, reliable, low maintenance. Works only when the furnace is running. Popular brands: Aprilaire 400/500, Honeywell HE225.
Fan-Powered Humidifier
Similar to bypass but with its own blower — can add humidity even when the furnace isn't actively heating. More expensive but more effective for very large homes or very dry climates. Popular: Aprilaire 700.
Steam Humidifier
Heats water to create steam, which is injected into the air stream. Most precise humidity control, works independently of furnace operation, but highest cost ($600–$1,200 installed) and requires more maintenance. Best for very large homes or those with specific medical humidity requirements.
What Humidity Level Is Comfortable?
ASHRAE recommends 30–50% relative humidity for human comfort and health. In Minnesota winters, unhumidified homes typically run 10–20% RH. At 30–40% RH, you'll notice the difference: less static electricity, better sleep quality, reduced frequency of respiratory irritation, and wood in your home stays dimensionally stable.
Cost and Installation
Bypass humidifiers installed on your furnace typically cost $400–$700 installed. Fan-powered units run $500–$900. Steam humidifiers: $800–$1,500. The best time to install is when replacing your furnace — it can be added as part of the same job, minimizing labor costs. A humidifier installed at furnace replacement time adds minimal labor cost vs. a standalone installation later.
Maintenance: What's Required
Bypass and fan-powered humidifiers require annual maintenance:
- Replace the evaporator pad each year (or when visibly caked with mineral deposits)
- Clean the water panel and distribution tray
- Check the water supply line and solenoid valve
- At season end (spring), close the bypass damper and shut off water supply to prevent summer over-humidification
This is straightforward DIY maintenance — pads cost $15–$30 and replacement takes 15 minutes.
Does a humidifier make your home feel warmer?
Yes — humid air feels warmer than dry air at the same temperature (the "muggy summer" effect works in winter too). Many homeowners find they can lower their thermostat 2–3 degrees with proper humidification and maintain the same comfort level. This can partially offset the cost of the humidifier through reduced gas consumption.
Can too much humidity be a problem in Minnesota?
Yes — over-humidification causes condensation on windows, which can lead to mold and wood rot over time. The recommended target in Minnesota is 30–35% RH when outdoor temps are below 20°F, and 25–30% when outdoor temps are below 0°F. Most whole-home humidifiers have an outdoor temperature sensor (humidistat) that adjusts output automatically to prevent condensation.
Will a humidifier affect my furnace filter?
Slightly — a humidifier adds moisture to the air stream, which can cause filters to load slightly faster in some conditions. Check your filter at 60 days the first season with a new humidifier. In most homes, the impact on filter replacement frequency is minimal.
Does Furnace Direct offer humidifiers?
Furnace Direct specializes in Goodman furnace systems — contact us to discuss compatible whole-home humidifier options that can be added to your furnace installation. The ideal time to add a humidifier is when replacing your furnace, minimizing installation labor. Call (888) 762-1334 to discuss options.
Complete Your Comfort System — Furnace + Humidifier
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