AprilAire 700 Whole-House Fan Powered Evaporative Humidifier
MODEL 700 FEATURES:
- HUMIDITY FOR HEALTH: AprilAire Humidifiers can help you maintain optimal humidity in your home which has been shown to reduce the incidence of respiratory infections and symptoms related to allergies and asthma by minimizing the formation of bacteria and viruses.
- HUMIDITY FOR COMFORT: Balance your humidity to preserve your home and protect its occupants from dry air issues like static shock and chapped skin.
- PROTECT YOUR HOME: Preserve your home and any contents susceptible to damage from changing humidity or dry conditions.
- BUY WITH CONFIDENCE: This humidifier was designed and manufactured in the USA by AprilAire—the inventor of the whole-house evaporative humidifier, and the leader in Indoor Air Quality since 1954.
- ONBOARD CONTROL SENSOR: Automatically turns on the HVAC fan to measure the relative humidity inside the ductwork and from all parts of the home. Turns on the humidifier whenever the measured humidity drops below the set point.
- CONVENIENT CONTROL: To monitor and adjust the humidity with a high-contrast digital screen.
- WHOLE-HOUSE HUMIDIFICATION: For Ducted HVAC Systems.
- FULL COVERAGE: For tightly constructed homes up to 5,300 square feet, with a capacity of 18 gallons per day.*
BENEFITS:
Our fan-powered, duct-mounted humidifier adds balanced humidity to your whole home. The fan pulls air directly from your furnace, moisturizing the air before returning it to the air ducts to be dispersed throughout your home.
INCLUDED IN THE BOX:
- Model 700 Humidifier
- Model 60 Digital Automatic Humidistat
- Model 35 Water Panel
- 24VAC Transformer
- Outdoor Temperature Sensor
- Saddle Valve
- Installation Instructions
What "Fan-Powered" Actually Means — and Why It Matters
The Key Difference from the Model 400
The AprilAire 400 (bypass humidifier) relies entirely on your furnace's own blower to push air through the water panel — meaning it only humidifies while your furnace happens to be running for heating. The Model 700 has its own dedicated fan, pulling air directly from the furnace and pushing it through the water panel independently of whether your heating system is actively calling for heat. This is a meaningful distinction: it means the 700 can maintain consistent humidity levels even during mild weather when your furnace cycles infrequently — a common gap with bypass-style humidifiers.
Why This Enables Greater Coverage
The added fan is also why the Model 700 covers more square footage than the 400 — up to 5,300 sq. ft. at 18 gallons/day, compared to the 400's 4,000–5,000 sq. ft. at 17 gallons/day. By actively forcing air through the water panel rather than relying on passive furnace airflow, the 700 can achieve more consistent evaporation and output regardless of furnace cycling patterns, making it a better fit for larger homes or homes with more demanding humidity needs.
The Onboard Control Sensor: Smarter Activation
Rather than only responding to a wall-mounted humidistat reading, the Model 700's onboard control sensor actively triggers your HVAC fan to sample humidity from air pulled throughout the ductwork — giving a more representative reading of your whole home's actual humidity level rather than relying on a single fixed sensor location. When that measured humidity drops below your setpoint, the system automatically activates.
What's Included and Why It Matters
The complete kit — including the Model 60 Digital Automatic Humidistat, Model 35 Water Panel, transformer, outdoor temperature sensor, and saddle valve — means this is a fully specified system rather than requiring separate component sourcing. The included outdoor temperature sensor is particularly important: like other AprilAire automatic models, it allows the system to adjust target humidity based on outdoor conditions, since the ideal indoor humidity setpoint shifts with outdoor temperature to avoid window condensation in colder weather.
Model 400 vs. Model 700: Which Fits Your Home?
| AprilAire 400 (Bypass) | AprilAire 700 (Fan-Powered) | |
|---|---|---|
| Air movement | Relies on furnace blower | Dedicated onboard fan |
| Coverage | Up to 4,000–5,000 sq ft | Up to 5,300 sq ft |
| Capacity | 17 gallons/day | 18 gallons/day |
| Best for | Standard homes, furnace runs frequently in season | Larger homes, or homes needing consistent humidity regardless of furnace cycling |
| Included sensors | Indoor humidity | Indoor humidity + outdoor temperature + ductwork sampling |
If you're unsure which model fits your home's size and furnace usage pattern, our technicians can evaluate your specific setup — see also the AprilAire 400 for smaller or standard homes, or the AprilAire 800 Steam Humidifier for the fastest, most precise response regardless of furnace or HVAC fan operation at all.
Professional Installation Matters
Because the Model 700 includes multiple components — humidistat, water panel, transformer, outdoor sensor, and saddle valve — that all need to be correctly wired and plumbed together, professional installation ensures the full system performs as designed. Our licensed HVAC technicians will:
- Mount the fan-powered unit and connect it to your furnace's ductwork
- Install the saddle valve and connect the water supply line
- Wire the transformer, Model 60 digital humidistat, and outdoor temperature sensor
- Configure the onboard control sensor and set your target humidity range
- Test fan activation and humidity response independent of furnace heating cycles
Frequently Asked Questions
Does the Model 700 run even when my furnace isn't heating?
Yes — because it has its own fan, it can pull and humidify air independently of whether the furnace is actively producing heat, unlike bypass models that rely entirely on furnace airflow.
How is the outdoor temperature sensor used?
It allows the system's digital control to automatically adjust the target indoor humidity level based on current outdoor temperature, helping prevent window condensation in colder weather while still maintaining comfortable humidity.
Is the Model 700 harder to install than the Model 400?
It has more components (fan, additional sensors) than the simpler bypass Model 400, so professional installation is especially recommended to ensure everything is wired and configured correctly.
At AprilAire, our mission has always been to make homes healthy through intuitive design and professional-grade solutions—because healthy homes are the foundation for healthy people, families, and communities.
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